| Title | Authors | Type | Journal | Publish Date | Description | Download | Center |
|---|---|---|---|---|---|---|---|
| Effective Recruitment for Building Energy Research | Outcault, Sarah; Perea, Cinthia Y.; Searl, Emily | Practitioner's Guide | 2026 | Barriers to participation in energy research exist at the participant, project, and system levels. This report documents best practices for recruiting participants in residential building energy research projects, with special considerations for vulnerable individuals, households, and communities. | Read Guide | mtrp | |
| From Lab to Living Room: Clean Energy Tech Adoption a Market Transformation Case Study | Sarah Outcault, Eli Alston-Stepnitz, Angela Sanguinetti, Ellian Eorwyn, Shahar Zach, Emily Searl | Conference Poster | 2026 | Barriers to adoption of clean energy technologies exist at the technical, workforce, policy, and consumer levels. This poster presents a market transformation case study of residential multi function heat pumps and outlines research methods used to identify barriers, engage stakeholders, and develop strategies that support successful technology adoption and market readiness. | Download Poster | mtrp | |
| Lessons from user experience with automated load flexibility | A Sanguinetti, E Alston-Stepnitz and S Outcault | Peer-reviewed Article | IOPScience | 2025 | Load flexibility (LF) is a crucial resource to enable sustainable and affordable building electrification and decarbonization. User acceptance of LF technologies is essential to their widespread utilization, however user perceptions and experiences with them are largely unknown. This paper presents findings about user experience with automated LF across a variety of technologies for residential and commercial buildings. | Read Article | mtrp |
| Market Study: Residential Multifunction Heat Pump | Scilia Pedroso, Eli Alston-Stepnitz, Sarah Outcault | Project Report | 2025 | Residential buildings account for a substantial share of California’s greenhouse gas emissions, underscoring the urgent need for efficient and scalable electrification solutions for space heating, cooling, and water heating. Residential air-to-air multifunction heat pumps (MFHPs) offer a potential pathway by integrating these services into a single system. The research applies a mixed-methods approach to identify key market barriers and opportunities for residential MFHPs, combining: (1) a landscape analysis of technical, policy, and market conditions; (2) interviews with 49 stakeholders representing 41 organizations; and (3) a representative survey of 961 California homeowners. | Read Report | wcec | |
| Lab Test of a Variable Speed Air-to-Air Multi-Function Heat Pump Final Report | Dr. David Vernon, Fred Meyers, Timothy Levering, David Braden and Morgane Gaucher | Project Report | 2025 | Residential Multi-Function Heat Pumps (MFHP) use one efficient compressor to provide space cooling, space heating, and domestic hot water heating. Variable-speed air-to-air MFHPs can have lower peak power consumption compared to the typical two separate heat pumps, for space conditioning and water heating. This means variable-speed MFHP may enable retrofit electrification without electrical service panel upgrades reducing cost and installation time. This project laboratory tested a 24kBtu/h (7.1kW) rated variable-speed air-to-air MFHP, measuring capacity and energy consumption in all operating modes across a range of outdoor conditions that match California climate zones. | Read Report | wcec | |
| Affordable Near- and Medium-Term Solutions for Integration of Low-GWP Heat Pumps in Residential Buildings | Curtis Harrington, Sarah Outcault, Emily Fricke, Sagal Alisalad, Vinod Narayanan, Erfan Rasouli, Valentina Arevalo Arredondo, Jingjuan Dove Feng, Antonea Frasier | Project Report | 2025 | This report describes the results from a project aimed at developing and demonstrating affordable and efficient heat pumps using refrigerants with low global warming potential (<750). The project team developed a near-term solution to address the existing need for affordable and efficient heat pump options that meet the upcoming refrigerant regulations. The medium-term solution advances air-to-water heat pump technology that offers a solution if refrigerant regulations become more stringent, requiring the use of highly flammable or toxic refrigerants. | Download Report | wcec | |
| Building materials could store more than 16 billion tonnes of CO2 annually | Elisabeth Van Roijen, Sabbie A Miller, Steven J Davis | Peer-reviewed Article | Science | 2025 | Achieving net-zero greenhouse gas emissions likely entails not only lowering emissions but also deploying carbon dioxide (CO2) removal technologies. We explored the annual potential to store CO2 in building materials. We found that fully replacing conventional building materials with CO2-storing alternatives in new infrastructure could store as much as 16.6 ± 2.8 billion tonnes of CO2 each year—roughly 50% of anthropogenic CO2 emissions in 2021. The total storage potential is far more sensitive to the scale of materials used than the quantity of carbon stored per unit mass of materials. Moreover, the carbon storage reservoir of building materials will grow in proportion to demand for such materials, which could reduce demand for more costly or environmentally risky geological, terrestrial, or ocean storage. | Read Paper | mdsc |
| Leveraging community resources to protect the most vulnerable: A case study on heat mitigation in India’s informal settlements | Outcault, S.M., Searl, E.A., & Gilani, V.M. | Conference Paper | 2024 | There is a great need for technical solutions that deliver comfort in extreme heat. Fair Conditioning works with vulnerable communities in India to co-create solutions to reduce solar heat gain in local buildings. They have developed innovative techniques to cool informal dwellings by deploying a spectrum of passive design techniques. | Read Paper | mtrp | |
| Harnessing non-energy impacts to promote residential heat pump adoption: Examples from the U.S. and beyond | Sarah Outcault, Emily Searl, Cinthia Magaña, and Eli Alston-Stepnitz | Conference Paper | 2024 | As countries strive to decarbonize residential buildings, air-source heat pumps (ASHPs) have emerged as crucial tools in this endeavor. However, challenges persist in promoting widespread adoption, including political resistance, economic barriers, and consumer perceptions. This paper explores the role of non-energy impacts (NEIs) in influencing heat pump adoption and examines how heat pump programs leverage NEIs to encourage uptake. | Read Report | mtrp | |
| Load Flexibility: Keeping Users in the Loop with “Invisible” Technologies | Angela Sanguinetti, Eli Alston-Stepnitz, Sarah Outcault, and Margaret Taylor | Conference Paper | 2024 | This paper focuses on user experience with emerging load flexible (LF) technologies, as demonstrated in residential and commercial building field sites in California. It draws from semi structured interviews with people who interacted with LF technologies or who had energy services affected by these technologies during testing of their responsiveness to electricity price and greenhouse gas signals simulating those expected as California’s grid evolves. | Read Report | mtrp | |
| Stakeholder perspectives on the role of standards in establishing a load flexible ecosystem | Sarah Outcault, Eli Alston-Stepnitz, Margaret Taylor | Conference Paper | 2024 | Technology standards emerge as a key driver with regard to market stimulation, innovation, and widespread adoption of interoperable load-flexible technologies that enable grid interactive energy-efficient buildings. This paper explores the “chicken and egg” issues related to the widespread adoption of load-flexible devices in the face of uncertain technology standards. | Read Report | mtrp | |
| What's the ETA for heat pump adoption? Assessing barriers and opportunities with the Energy Technology Adoptability framework | Conference Paper | 2024 | Air-source heat pumps (ASHPs) are a keystone technology to electrify and decarbonise buildings. Despite an abundance of programs to promote their adoption, uptake lags behind targeted rates in many regions. Research has highlighted a range of factors that hinder heat pump adoption, but it tends to focus on known barriers such as high initial costs and lack of awareness among potential customers. This paper takes a systematic approach to exploring barriers to heat pump adoption, using the Energy Technology Adoptability (ETA) framework. | Read Paper | mtrp | ||
| SLIDE DECK: What's the ETA for heat pump adoption? Assessing barriers and opportunities with the Energy Technology Adoptability framework | Sarah Outcault | Conference Slides | 2024 | Air-source heat pumps (ASHPs) are a keystone technology to electrify and decarbonise buildings. Despite an abundance of programs to promote their adoption, uptake lags behind targeted rates in many regions. Research has highlighted a range of factors that hinder heat pump adoption, but it tends to focus on known barriers such as high initial costs and lack of awareness among potential customers. This paper takes a systematic approach to exploring barriers to heat pump adoption, using the Energy Technology Adoptability (ETA) framework. | View Slides | mtrp | |
| Database of residential heat pump promotion efforts | Sarah Outcault | Database | 2024 | Searchable database of utility, government, and community-led programs and activities to promote residential heat pump adoption by addressing the technology's trialability, observability, complexity of installation, and non-energy benefits. | View Database (Excel file) | mtrp | |
| Innovative Approaches to Residential Heat Pump Promotion | Sarah Outcault, Eli Alston-Stepnitz, Ellian Eorwyn, Cinthia Magana & Emily Searl | Project Report | 2024 | California has identified heat pumps as a keystone technology on its path to decarbonization. To achieve the state’s goal of reaching six million heat pump installations by 2030, however, adoption rates must accelerate substantially. While various rebate programs have been introduced to alleviate the initial cost burden associated with heat pump installation, it is imperative to acknowledge and address critical non-cost barriers that may impede widespread adoption. | Read Report | mtrp | |
| Residential Multi-Function Heat Pump Laboratory Testing Final Report | Dave Vernon, Subhrajit Chakraborty | Project Report | 2024 | Residential Multi-Function Heat Pumps (MFHP) use one efficient compressor to provide space cooling, space heating, and domestic hot water heating. MFHPs can have lower peak power consumption compared to the typical two separate heat pumps, for space conditioning and water heating, and may enable retrofit electrification without electrical service panel upgrades reducing cost and installation time. This project laboratory tested a commercially available single-speed air-to-air MFHP measuring capacity and energy consumption in all operating modes across a range of outdoor conditions that match California climate zones. The measured results were analyzed to develop performance curves that future projects will use in simulation tools to estimate annual energy savings in residential buildings across climate zones. | Read Report | wcec | |
| Load Flexibility Control of Three Field Installed Single Speed MFHPs with Dynamic Pricing | Green, Christy; Chakraborty, Subhrajit; Vernon, David | Academic Paper | 2024 | This study evaluates the load flexibility of a multi-function heat pump(MFHP) system responding to a dynamic price signal. The residential MFHP uses a single air-source heat pump outdoor unit to efficiently meet both water heating and space conditioning needs. The MFHP does not require electric resistance heaters for emergency heat or defrost, potentially avoiding the need for electrical panel upgrades commonly required when replacing gas appliances. | Read Paper | wcec | |
| Residential Multi-Function Heat Pump: Heat Exchanger Improvement Project | David Vernon | Project Report | 2024 | The design of the heat exchangers has a significant impact on energy efficiency, cost, and the amount of refrigerant required in the system. This study collected specifications and cost data for commercially available heat exchangers, built computer models of the refrigerant-to-water and water-to-water heat exchangers, and completed a techno-economic analysis to recommend designs that can increase efficiency, reduce cost, and reduce refrigerant greenhouse gas (GHG) impacts. | Read Report | wcec | |
| Load Flexibility: Keeping Users in the Loop with “Invisible” Technologies | Angela Sanguinetti, Eli Alston-Stepnitz, Sarah Outcault, and Margaret Taylor | Conference Paper | 2024 | This paper focuses on user experience with emerging load flexible (LF) technologies, as demonstrated in residential and commercial building field sites in California. It draws from semi structured interviews with people who interacted with LF technologies or who had energy services affected by these technologies during testing of their responsiveness to electricity price and greenhouse gas signals simulating those expected as California’s grid evolves. | Read Paper | wcec | |
| Laboratory Testing of MSP Technology's Dehumidification System | Derrick Ross, Robert McMurry, and Theresa Pistochini | Project Report | 2024 | The objective of this project was to conduct laboratory testing and analysis of MSP Technology’s dehumidification system and subsequently incorporate the data into a numerical model to estimate the annual energy savings produced by using MSP Technology’s dehumidification system over a traditional dehumidification system. | Read Paper | wcec | |
| A review of current practice for life cycle assessment of cement and concrete | Josefine A Olsson, Sabbie A Miller, Joshua D Kneifel | Peer-reviewed Article | Resources, Conservation and Recycling | 2024 | Concrete production is a significant contributor to global anthropogenic greenhouse gas (GHG) emissions due to its extensive use. These notable impacts have driven a desire to quantify the environmental burdens and pathways to reduce burdens of this product, commonly through Life Cycle Assessment (LCA) methodology. Here, we review the application of the LCA methodology in assessing various decarbonization strategies and areas where accuracy of quantitative environmental impact assessments for comparison can be improved. | Read Report | mdsc |
| The climate benefits from cement carbonation are being overestimated | Elisabeth Van Roijen, Kati Sethares, Alissa Kendall, Sabbie A Miller | Peer-reviewed Article | Nature Communications | 2024 | Rapid decarbonization of the cement industry is critical to meeting climate goals. Oversimplification of direct air capture benefits from hydrated cement carbonation has skewed the ability to derive decarbonization solutions. Here, we present both global cement carbonation magnitude and its dynamic effect on cumulative radiative forcing. | Read Report | mdsc |
| Mass, enthalpy, and chemical‐derived emission flows in mineral processing | Seth Kane, Sabbie A Miller | Peer-reviewed Article | Journal of Industrial Ecology | 2024 | The production of materials from mineral resources is a significant contributor to anthropogenic CO2 emissions. This contribution is driven primarily by chemical CO2 emissions from the conversion of mineral resources and emissions tied to energy demands for material processing. In this work, we synthesize the thermodynamically required enthalpy and chemically derived emissions of mineral processing and consumption in the United States. | Read Report | mdsc |
| Combined cement and steel recycling could cut CO2 emissions | Sabbie A Miller | Peer-reviewed Article | Nature | 2024 | Cement can be reused by including it as a component of steel recycling. This opens the way to an industrial partnership that improves the use of materials and lowers carbon emissions — but only if waste resources are well managed. | Read Report (paywall) | mdsc |
| Assessing uncertainty in building material emissions using scenario-aware Monte Carlo simulation | Ahmad Bin Thaneya, Aysegul Petek Gursel, Seth Kane, Sabbie A Miller, Arpad Horvath | Peer-reviewed Article | Environmental Research: Infrastructure and Sustainability | 2024 | Global greenhouse gas emissions from the built environment remain high, driving innovative approaches to develop and adopt building materials that can mitigate some of those emissions. However, life-cycle assessment (LCA) practices still lack standardized quantitative uncertainty assessment frameworks, which are urgently needed to robustly assess mitigation efforts. | Read Report | mdsc |
| Predicting biochar properties and pyrolysis life-cycle inventories with compositional modeling | Seth Kane, Sabbie A Miller | Peer-reviewed Article | Bioresource Technology | 2024 | Biochar, formed through slow pyrolysis of biomass, has garnered attention as a pathway to bind atmospheric carbon in products. However, life cycle assessment data for biomass pyrolysis have limitations in data quality, particularly for novel processes. | Read Report | mdsc |
| Technical, economic, and environmental feasibility of rice hull ash from electricity generation as a mineral additive to concrete | Jin Wook Ro, Patrick R Cunningham, Sabbie A Miller, Alissa Kendall, John Harvey | Peer-reviewed Article | Scientific Reports | 2024 | A circular economy based on symbiotic relationships among sectors, where the waste from one is resource to another, holds promise for cost-effective and sustainable production. This research explores such a model for the agriculture, energy, and construction sectors in California. | Read Report | mdsc |
| Towards the production of net-negative greenhouse gas emission bio-based plastics from 2nd and 3rd generation feedstocks | Elisabeth Van Roijen, Sabbie A Miller | Peer-reviewed Article | Journal of Cleaner Production | 2024 | Here, we show production pathways for greenhouse gas (GHG)-negative bio-based plastics from 2nd and 3rd generation feedstocks. We focus on bio-based plastics that are technically capable of replacing 80% of the global plastic market. | Read Report | mdsc |
| Aligning renewable energy expansion with climate-driven range shifts | Uzma Ashraf, Toni Lyn Morelli, Adam B. Smith & Rebecca R. Hernandez | Peer-reviewed Article | Nature Climate Change | 2024 | Fossil fuel dependence can be reduced, in part, by renewable energy expansion. Increasingly, renewable energy siting seeks to avoid significant impacts on biodiversity but rarely considers how species ranges will shift under climate change. Here we undertake a systematic literature review on the topic and overlay future renewable energy siting maps with the ranges of two threatened species under future climate scenarios to highlight this potential conflict. | Read Report (paywall) | we |
| Defining Voltaic Landscapes for Sustainability | Rebecca Hernandez | Research Report | 2024 | This report examines the integration of solar energy production with agricultural and ecological land uses, analyzing the benefits, challenges, and stakeholder perspectives on such multi-use systems. | Read Report | wild | |
| CalFlexHub Stakeholder Needs Assessment - Year 2 | Sarah Outcault, Eli Alston-Stepnitz, Ellian Carone, Sagal Alisalad, and Cinthia Magaña, Margaret Taylor | Project Report | 2023 | The goal of the California Load Flexibility Research and Development Hub (CalFlexHub) is to demonstrate cost-effective and reliable load-flexible and flexibility-enabling technologies that could support a California future in which significant grid incorporation of renewable energy is balanced by electricity demand that is flexible throughout the year's 8,760 hours. One of CalFlexHub's tasks is to use social science methods to gain a better understanding of the broader context of these technologies. This report is the second of three annual CalFlexHub “stakeholder needs assessments” under this task; each will discuss what stakeholders identify priorities, constraints, and needs as they relate to implementing California’s vision for automated load flexibility and dynamic electricity prices. | Read Report | mtrp | |
| Cost-Constrained Optimization of Energy Efficiency for Multi-family and Commercial Buildings | David Vernon, Mazen Daher, Mark Modera | Project Report | 2023 | This project provides California stakeholders with cost-optimized selections of technology packages for building cost-effective and high-efficiency multi-family residential and commercial buildings. A detailed cost and energy performance analysis was used to identify measures and packages that most closely approach zero-net energy for each building type in each state climate zone. | Read Report | wcec | |
| A review of drivers for implementing geopolymers in construction: Codes and constructability | Andrés Martínez, Sabbie A Miller | Peer-reviewed Article | Resources, Conservation and Recycling | 2023 | Geopolymer concrete (GPC) has emerged as an alternative to Portland cement (PC) concrete in recent decades, with recent drivers for its use being tied to its potential environmental sustainability benefits and comparable performance. However, many aspects influencing its implementation are yet to be fully addressed. | Read Report | mdsc |
| Harmonized Life-Cycle Inventories of Nanocellulose and Its Application in Composites | Seth Kane, Sabbie A Miller, Kimberly E Kurtis, Jeffrey P Youngblood, Eric N Landis, W Jason Weiss | Peer-reviewed Article | Environmental Science & Technology | 2023 | Cellulose nanocrystals (CNC) and nanofibers (CNF) have been broadly studied as renewable nanomaterials for various applications, including additives in cement and plastics composites. Herein, life cycle inventories for 18 previously examined processes are harmonized, and the impacts of CNC and CNF production are compared with a particular focus on GHG emissions. | Read Report | mdsc |
| Meeting industrial decarbonization goals: a case study of and roadmap to a net-zero emissions cement industry in California | Alyson Kim, Sabbie A Miller | Peer-reviewed Article | Environmental Research Letters | 2023 | Recent decarbonization policies are expected to significantly impact high greenhouse gas (GHG) emitting industries, as they will be forced to find ways to operate with a lower environmental footprint. Due to the energy required for the kilns and the unavoidable chemical-derived emissions during manufacturing, in addition to its high global consumption levels, the cement industry is anticipated to be among the early industries affected. | Read Report | mdsc |
| Near-term Pathways for Decarbonizing Global Concrete Production | Josefine A Olsson, Sabbie A Miller, Mark G Alexander | Peer-reviewed Article | Nature Communications | 2023 | Growing urban populations and deteriorating infrastructure are driving unprecedented demands for concrete, a material for which there is no alternative that can meet its functional capacity. The production of concrete, more particularly the hydraulic cement that glues the material together, is one of the world’s largest sources of greenhouse gas (GHG) emissions. While this is a well-studied source of emissions, the consequences of efficient structural design decisions on mitigating these emissions are not yet well known. Here, we show that a combination of manufacturing and engineering decisions have the potential to reduce over 76% of the GHG emissions from cement and concrete production, equivalent to 3.6 Gt CO2-eq lower emissions in 2100. | Read Report | mdsc |
| The Influence of Biochar on the Flow Properties, Early Hydration, and Strength Evolution of Paste | Wolfram Schmidt, Louise Midroit, Patrick R Cunningham, Sabbie A Miller, Sofiane Amziane | Conference Paper | International Conference on Bio-Based Building Materials | 2023 | In order to reduce the carbon footprint, biochar can be used as CO2-negative concrete constituent. The paper shows results of experiments with cement paste and mortar mixtures with 5%, 15% and 30% of cement volume replaced by biochar. | Read Paper (paywall) | mdsc |
| Optimizing supplementary cementitious material replacement to minimize the environmental impacts of concrete | Kelli A Knight, Patrick R Cunningham, Sabbie A Miller | Peer-reviewed Article | Cement and Concrete Composites | 2023 | With growing environmental consequences from material consumption, there is increased urgency to decarbonize the production of materials we consume frequently, including concrete. It is common to use supplementary cementitious materials (SCMs) to limit the clinker content of Portland cement and reduce greenhouse gas (GHG) emissions in concrete production. However, over-utilization of SCMs can degrade material performance and increase other environmental impacts. | Read Report | mdsc |
| Cellulose Nanocrystals as a Value-Based Additive for Low Carbon Footprint Concrete with Limestone | Krishna Siva Teja Chopperla, Sivakumar Ramanathan, Keshav Bharadwaj Ravi, Angel Mateos, John Harvey, Somayeh Nassiri, Jeffrey Alan Buscheck, Sabbie Miller, O Burkan Isgor, W Jason Weiss | Project Report | 2023 | This project evaluated cellulose nanocrystals (CNCs) as an additive that can aid in concrete 3 mixture modifications in an effort to reduce concrete’s carbon footprint. This project explored the 4 use of CNCs in cementitious materials containing various amounts of limestone (LS). | Read Report | mdsc | |
| Engineering the performance of post-consumer calcium carbonate from carpet in cement-based materials through pre-treatment methods | Patrick R Cunningham, Peter G Green, Sanjai J Parikh, John T Harvey, Sabbie A Miller | Peer-reviewed Article | Construction and Building Materials | 2023 | Using post-consumer carpet calcium carbonate (PC4) in concrete can support a circular economy. Three treatments were evaluated to engineer PC4: furnacing at 600°C, furnacing at 900°C, and milling. | Read Report | mdsc |
| Solar Energy-driven Land-cover Change Could Alter Landscapes Critical to Animal Movement in the Continental United States | Michael O. Levin, Elizabeth L. Kalies, Emma Forester, Elizabeth L. A. Jackson, Andrew H. Levin, Caitlin Markus, Patrick F. McKenzie, Jared B. Meek, and Rebecca R. Hernandez | Peer-reviewed Article | Environmental Science & Technology | 2023 | The United States may produce as much as 45% of its electricity using solar energy technology by 2050, which could require more than 40,000 km2 of land to be converted to large-scale solar energy production facilities. Little is known about how such development may impact animal movement. Here, we use five spatially explicit projections of solar energy development through 2050 to assess the extent to which ground-mounted photovoltaic solar energy expansion in the continental United States may impact land-cover and alter areas important for animal movement. | Read Report (paywall) | we |
| Technology Characteristics that Influence Adoption of Residential Distributed Energy Resources: Adapting Rogers’ Framework | Sarah Outcault, Angela Sanguinetti, Leslie Nelson | Peer-reviewed Article | Energy Policy | 2022 | Distributed energy resources (DERs) present an important opportunity to lower the carbon intensity of residential buildings but face numerous barriers to adoption. This paper extends and adapts Rogers' theory of the role of technology characteristics in the diffusion of innovation (Rogers, 1962) to address the unique features of residential DERs. | Read Report | mtrp |
| Building lower-carbon affordable housing: case studies from California | Sarah Outcault, Eli Alston-Stepnitz, Angela Sanguinetti, Ashley N. DePew & Cinthia Magaña | Peer-reviewed Article | Building Research and Information | 2022 | This research explores developers’ experiences with lower-carbon multi-family affordable housing in California using three case studies that illustrate different pathways to decarbonization – improving efficiency, eliminating fossil fuel combustion for end-uses, and adopting a zero-net energy design. | Read Report (paywall) | mtrp |
| Occupant Non-Energy Impact Identification Framework: A human-centered approach to understanding residential energy retrofits | Sarah Outcault, Angela Sanguinetti, Nermin Dessouky, Cinthia Magaña | Peer-reviewed Article | Energy and Buildings | 2022 | Residential energy retrofits have the potential to generate significant non-energy impacts (NEIs) on occupants, but the understanding of those NEIs has been hampered by the lack of a shared approach to studying them. A detailed literature review revealed several common tendencies that limit the generalizability of findings, including a focus on benefits, different categorization schemes, varied scope and specificity, the conflation of impacts across occupant groups, and conflation of retrofits’ functional outcomes with occupant impacts. This paper suggests a more systematic way of conceptualizing NEIs is needed and proposes a new framework that supports a comprehensive, unbiased, human-centered, and standardized approach. | Read Report (paywall) | mtrp |
| Understanding teachers' experiences of ventilation in California K- 12 classrooms and implications for supporting safe operation of schools in the wake of the COVID-19 pandemic | Angela Sanguinetti, Sarah Outcault, Theresa Pistochini, Madison Hoffacker | Peer-reviewed Article | Wiley | 2022 | Classrooms are often under-ventilated, posing risks for airborne disease transmission as schools have reopened amidst the COVID-19 pandemic. While technical solutions to ensure adequate air exchange are crucial, this research focuses on teachers’ per-ceptions and practices that may also have important implications for achieving a safe classroom environment. | Read Report | mtrp |
| Modeling Impacts of Ventilation and Filtration Methods on Energy Use and Airborne Disease Transmission in Classrooms | Theresa Pistochini, Caton Mande, Subhrajit Chakraborty | Peer-reviewed Article | Journal of Building Engineering | 2022 | The benefits of increased ventilation and filtration for reducing disease transmission compared to drawbacks of reduced thermal comfort and increased energy consumption and electricity demand are not well described. A comprehensive simulation of outdoor air ventilation rates and filtration methods was performed with a modified Wells-Riley equation and EnergyPlus building simulation to understand the trade-offs between infection probability and energy consumption for a simulated classroom in 13 cities across the US. | Read Report | wcec |
| Packaged Roof Top Unit with Integrated Heat Pump and Indirect/Direct Evaporative Cooling | Theresa Pistochini, Robert McMurry | Technical Report | 2022 | The emerging technology assessed in this study is a packaged RTU that integrates a heat pump (HP) with an indirect-direct evaporative cooling(IDEC) system that is designed as a direct replacement for a traditional RTU. This project evaluates the packaged heat pump with IDEC in a field study and compares its performance to a baseline packaged RTU. | Read Report | wcec | |
| Greenhouse Gas Analysis of Proposed HVAC Designs for the Davis Innovation Sustainability Campus | Dr. David Vernon, Mazen Daher | Technical Report | 2022 | The Davis City Council has required that the proposed Davis Innovation Sustainability Campus use an all-electric, high efficiency HVAC design that would be 30% more efficient than Title 24 code requirements using the Time Dependent Valuation metric. To meet this requirement, the HVAC design would use packaged air source heat pumps on each of the buildings. Upgrading the HVAC systems to a district energy system with all electric central equipment including a chiller, heat pump, thermal energy storage tanks, and a geothermal bore field has the potential to be even more efficient than the required design. | Read Report | wcec | |
| Characterizing the performance of a do-it-yourself (DIY) box fan air filter | Rachael Dal Porto, Monet N. Kunz, Theresa Pistochini, Richard L. Corsi & Christopher D. Cappa | Peer-reviewed Article | Aerosol Science and Technology | 2022 | Air filtration serves to reduce concentrations of particles in indoor environments. Most standalone, also referred to as portable or in-room, air filtration systems use HEPA filters, and cost generally scales with the clean air delivery rate. A “do-it-yourself” lower-cost alternative, known as the Corsi-Rosenthal Box, that uses MERV-13 filters coupled with a box fan has been recently proposed, but lacks systematic performance characterization. We have characterized the performance of a five-panel Corsi-Rosenthal air cleaner using both research-grade instrumentation (an aerodynamic particle sizer, APS) and a low-cost particle sensor. | Read Report | wcec |
| Greenhouse Gas Emission Forecasts for Electrification of Space Heating in Residential Homes in the USG | Theresa Pistochini, Mitchal Dichter, Subhrajit Chakraborty, Nelson Dichter, Aref Aboud | Peer-reviewed Article | Energy Policy | 2022 | This study aims to inform policymakers about the greenhouse gas emission impacts of heat pump deployment in residential homes. Electric heat pumps eliminate direct burning of fossil fuels in homes but result in indirect emissions due to fossil fuels burned for electricity production. This paper presents the first detailed emission forecasts for operating either a heat pump or gas furnace for residential heating over a 15-year period, starting in year 2022 through 2036, in six regions across the US. | Read Report | wcec |
| R-466A Refrigerant Demonstration and Performance | Curtis Harrington, Fred Meyers | Case Study | 2022 | Refrigerants used in vapor-compression air conditioners and heat pumps have been the subject of environmental regulations requiring the need to develop alternative solutions with lower global warming potential (GWP). In general, there is a trade-off when choosing alternative refrigerants between safety, performance, and GWP. | Read Report | wcec | |
| Residential Multi-Function Heat Pumps: Product Search | David Vernon | Project Report | 2022 | This proposed technical market characterization project will complete a product search from the largest HVAC and hot water heating equipment manufacturers to identify what residential air-to-air multi-function heat pump products are commercially available or soon to be commercially available in California. This project will be a combination of primary research surveying manufacturers as well as secondary research through literature searches. | Read Report | wcec | |
| Analysis of Refrigerant Use for AC Equipment Maintenance | Theresa Pistochini, Roger Silveira, Derrick Ross, Robert McMurry, Adarsh Umarani | Academic Journal Paper | 2022 | Understanding refrigerant emissions from air-conditioning (AC) equipment is critical for accurately estimating its global warming impacts. The goal of the study described in this article was to develop a primary data collection method to estimate average refrigerant emission rates of R-22 and R-410A in AC equipment by examining historical refrigerant used relative to the initial refrigerant charge of the AC equipment inventory. | Read Paper | wcec | |
| Timing is Everything: Optimizing Load flexibility of Heat Pump Water Heaters for Cost, Comfort, and Carbon Emissions | Caton Mande, Aref Aboud, Loren dela Rosa, Rachael Collins, Matthew J. Ellis | Conference Paper | 2022 | As California continues to decarbonize the electrical grid and more customers electrify, load flexibility among heat pumps is becoming critical for maximizing the use of carbon-free electricity sources, stabilizing the electricity grid, and minimizing operating costs to end-users. Economic model predictive control (MPC) is an advanced control technique that can provide automated load flexibility due to its ability to account for time-varying electric tariffs and available energy storage. A new configurable control framework is motivated and described to address the challenges of configuring economic MPC for deployment in heat pump water heaters. | Read Paper | wcec | |
| Concurrent Space Cooling and Hot water Heating through Compact Heat Pumps for All-electric Residential Buildings | Subhrajit Chakraborty, Robert Mcmurry, Curtis Harrington | Conference Paper | 2022 | Multi-function heat pumps can use the compressor heatduring a space cooling operation, which is otherwise wasted to the ambient through the condenser coil, to heat up water for domestic use. This project tested a multi-function heat pump that combines space cooling, dehumidification, ventilation, and domestic hot water (DHW) in a compact system (POD). | Read Paper | wcec | |
| Aerosol Sealing of Existing Residences | Curtis Harrington, Frederick Meyers, David Bohac, Melissa Anders, and Lindsay Genty | Conference Paper | 2022 | This paper describes the air leakage reductions achieved in an ongoing U.S. Department of Energy Building America project that integrates an aerosol-based sealing technology used primarily for new residential construction into existing home retrofits. | Read Paper | wcec | |
| R-466A Refrigerant Demonstration | Curtis Harrington, Fred Meyers | Case Study | 2022 | Refrigerants used in vapor-compression air conditioners and heat pumps have been the subject of environmental regulations requiring the need to develop alternative solutions with lower global warming potential (GWP). In general, there is a trade-off when choosing alternative refrigerants between performance, GWP, and safety. | Download | wcec | |
| Untapped potential: leak reduction is the most cost-effective urban water management tool | Amanda Rupiper, Joakim Weill, Ellen Bruno, Katrina Jessoe and Frank Loge | Peer-reviewed Article | IOP Science | 2022 | Providing sufficient, safe, and reliable drinking water is a growing challenge as water supplies become more scarce and uncertain. Meanwhile, water utilities in the United States lose approximately 17% of their delivered water to leaks each year. Using data from over 800 utilities across four U.S. states, California, Georgia, Tennessee, and Texas, we characterize the heterogeneity in water losses across the U.S., develop a model to assess the economically efficient level of losses, and use this model to compare the net benefits of several proposed water loss regulations and modeling approaches. | Read Report | cwee |
| OpenConcrete: a tool for estimating the environmental impacts from concrete production | Alyson Kim, Patrick R Cunningham, Kanotha Kamau-Devers and Sabbie A Miller | Peer-reviewed Article | IOP Science | 2022 | As the increasing global consumption of concrete drives notable environmental burdens from its production, particularly greenhouse gas (GHG) emissions, interest in mitigation efforts is increasing. Yet current environmental impact quantification tools rely on user decision-making to select data for each concrete constituent, have inconsistent scopes and system boundaries, and often utilize third-party life cycle inventories. These factors limit customization or tracking of data and hinder the ability to draw robust comparisons among concrete mixtures to mitigate its environmental burdens. To address these issues, we introduce a cohesive, unified dataset of material, energy, and emission inventories to quantify the environmental impacts of concrete. | Read Report | mdsc |
| Cement substitution with secondary materials can reduce annual global CO2 emissions by up to 1.3 gigatons | Izhar Hussain Shah, Sabbie A Miller, Daqian Jiang, Rupert J Myers | Peer-reviewed Article | Nature Communications | 2022 | Population and development megatrends will drive growth in cement production, which is already one of the most challenging-to-mitigate sources of CO2 emissions. However, availabilities of conventional secondary cementitious materials (CMs) like fly ash are declining. | Read Report | mdsc |
| A material flow analysis of carpet in the United States: Where should the carpet go? | Patrick R Cunningham, Sabbie A Miller | Peer-reviewed Article | Journal of Cleaner Production | 2022 | On average in 2018, each person in the United States (US) used approximately 28 m2 of carpet. Relative to other building materials, carpet has a short lifespan (4–25 years) and its frequent disposal requires notable landfill volume. Limited understanding of the types and magnitude of resources available from carpet disposals has limited exploration into their contributions to the circular economy. | Read Report | mdsc |
| Literature review on policies to mitigate GHG emissions for cement and concrete | Pablo Busch, Alissa Kendall, Colin W Murphy, Sabbie A Miller | Peer-reviewed Article | Resources, Conservation and Recycling | 2022 | The production and use of cement, the binding agent in concrete, emits seven percent of global greenhouse gas emissions annually. Achieving climate change mitigation targets, such as those proposed in the Paris Agreement, requires emission reductions from this sector. | Read Report | mdsc |
| Reducing the environmental impacts of plastics while increasing strength: Biochar fillers in biodegradable, recycled, and fossil-fuel derived plastics | Seth Kane, Elisabeth Van Roijen, Cecily Ryan, Sabbie Miller | Peer-reviewed Article | Composites Part C: Open Access | 2022 | In this study, material characterization and a cradle-to-gate life cycle assessment methodology are applied to examine how the addition of biochar as a filler in recycled plastics (rHDPE) influences material properties and environmental burdens. | Read Report | mdsc |
| Industrial Decarbonization: Policy Pathwaysfor the Cement & Concrete Sector | Pablo Busch, Alissa Kendall, Colin Murphy, Sabbie Miller | Policy Brief | 2022 | Globally, cement production is one of the key contributors to anthropogenic CO2 emissions from the industrial sector. Cement is a key constituent in the production of concrete and mortar, which are critical infrastructure materials used worldwide. | Read Report | mdsc | |
| A review of bioplastics at end-of-life: Linking experimental biodegradation studies and life cycle impact assessments | Elisabeth C Van Roijen, Sabbie A Miller | Peer-reviewed Article | Resources, Conservation and Recycling | 2022 | This review examines cradle-to-grave life cycle assessments (LCAs) and biodegradation studies of common bioplastics. Fueled by a growing single-use consumer base, the rate at which plastics are produced and disposed of is outpacing most other man-made materials, which is leading to substantial environmental impacts. | Read Report | mdsc |
| Using a micromechanical viscoelastic creep model to capture multi-phase deterioration in bio-based wood polymer composites exposed to moisture | Kanotha Kamau-Devers, Sabbie A Miller | Peer-reviewed Article | Construction and Building Materials | 2022 | To accurately depict in-service behavior of multi-phase, fully bio-based composites, models must be able to capture material deterioration. In this work, a viscoelastic micromechanical creep model, validated by experimental work, was proposed for bio-based wood polymer composites subject to moisture and prolonged loading. | Read Report | mdsc |
| Hourly accounting of carbon emissions from electricity consumption | Gregory J Miller, Kevin Novan and Alan Jenn | Peer-reviewed Article | IOP Science | 2022 | Carbon accounting is important for quantifying the sources of greenhouse gas (GHG) emissions that are driving climate change, and is increasingly being used to guide policy, investment, business, and regulatory decisions. The current practice for accounting emissions from consumed electricity, guided by standards like the GHG protocol, uses annual-average grid emission factors, although previous studies have shown that grid carbon intensity varies across seasons and hours of the day. | Read Report | |
| Decarbonizing Affordable Housing: Case Studies on Developer Experiences with New Construction | Sarah Outcault, Ph.D., Eli Alston-Stepnitz, M.A., Angela Sanguinetti, Ph.D., Ashley DePew, and Cinthia Magana | Project Report | 2021 | This report explores stakeholders’ experience developing lower-carbon affordable multi-family housing. Three case communities in California were studied to yield insights about the decisions, challenges, and successes that emerged in the design, financing, operation, and maintenance of the buildings. | Read Report | mtrp | |
| Residential Electrification in Sacramento and Its Impact on Residential Appliance Sales | Sarah Outcault, Ashley DePew, Yemi Akoda, and Alan Meier | Project Report | 2021 | The objective of this report is to investigate and quantify the market for appliances related to residential electrification and decarbonization, using the Sacramento Municipal Utility District (SMUD) as a case study. | Read Report | mtrp | |
| Design Specifications for Indoor Environmental Quality Feedback | Outcault, Sarah; Sanguinetti, Angela; Alston-Stepnitz, Eli | Presentation | Norwegian University of Science and Technology | 2021 | This presentation outlines best practices on IEQ information granularity, building upon the eco-feedback design-behavior framework. | Presentation Slides | mtrp |
| Residential solar water heating: California adopters and their experiences | Angela Sanguinetti, Sarah Outcault, Eli Alston-Stepnitz, Mithra Moezzi, Aaron Ingle | Peer-reviewed Article | Renewable Energy | 2021 | This research surveyed 227 single-family households with solar water heating across the state of California to understand their motivations and experiences, and draw implications regarding barriers to adoption. The survey explored households’ experiences across five stages of adoption, as outlined in Rogers’ Diffusion of Innovation theory: Knowledge, Persuasion, Decision, Implementation, and Confirmation. | Download (Paywall) | mtrp |
| Low-Cost, Large-Diameter Shallow Ground Loops for Ground-Coupled Heat Pumps | Curtis Harrington, Antash Najib, Vinod Narayanan, Mitchal Dichter, David Springer, Michael Slater, Peter Grant, Ada Liu, James Haile, Moncef Krarti, Joseph Huang | Project Report | 2021 | This project developed and validated modeling tools for simulating a ground heat exchanger technology that provides a less expensive method for implementing ground-source heat pumps and significantly reduces energy use in many California climate zones, furthering attainment of California’s energy goals. | Read Report | wcec | |
| Using non-invasive MEMS pressure sensors for measuring building envelope air leakage | Armando Casillas, Mark Modera, Marco Pritoni | Peer-reviewed Article | Energy and Buildings | 2021 | Micro-electromechanical systems (MEMS)-based sensors have seen significant improvements in accuracy and cost over the past several years, and due to the need for altitude sensing in unmanned aerial vehicles and wearable technologies, absolute pressure sensors have shown the most dramatic improvements. This paper investigates applications of MEMS sensors in commercial buildings. | Download (Paywall) | wcec |
| Considerations for Use and Selection of Portable Air Cleaners for Classrooms | Theresa Pistochini | White Paper | 2021 | Portable Air Cleaners with High Efficiency Particulate Air (HEPA) filtration are widely available. They are measured in terms of their “Clean Air Delivery Rate” (CADR) which is a measure of the cleaning speed of the system in removing particles in a controlled environment2. Portable air cleaners have CADR’s ranging from about 25-400 CFM (depending on size), and more than one could be used in a classroom to increase the amount of filtration provided. | Read Report | wcec | |
| Estimating Agricultural Groundwater Withdrawals with Energy Data | Jonathan Martindill, Robert Good, and Frank Loge | Peer-reviewed Article | Journal of Water Resources Planning and Management | 2021 | Agricultural water use is the leading cause of groundwater overdraft in California. However, agencies tasked with managing groundwater resources do not have access to accurate and reliable measurements of groundwater extraction. Previous studies identified a relationship between pump energy consumption and groundwater extraction and indicated that the efficiency lift method (ELM) can produce reliable estimates of groundwater extraction if based on reliable data. Recent advances in the availability of electricity and pump operating condition data have made the ELM viable for estimating large-scale groundwater extraction. | Read Article | cwee |
| Material Efficiency as a Means to Lower Environmental Impacts from Concrete | Sonoko Ichimaru Watanabe, Kanotha Kamau-Devers, Patrick R Cunningham, Sabbie A Miller | Policy Brief | 2021 | Concrete is a key component of the built environment. However, the manufacture of cement-based materials, such as concrete, produces over 8% of worldwide anthropogenic greenhouse gas (GHG) emissions. The largest contributor to the GHG emissions from concrete is associated with the manufacture of conventional cement, which reacts with water to “glue” rock fragments (aggregates) together to make concrete. | Read Report | mdsc | |
| Quantifying Environmental Impacts from Concrete Production, While Accounting for Data Variability and Uncertainty | Patrick R Cunningham, Sabbie A Miller | Policy Brief | 2021 | Concrete is the second most-used material on earth, surpassed only by water. Composed of cement (made by heating lime and clays at extremely high temperatures), crushed stone (aggregates), water, and other admixtures as needed, concrete is used in construction of roads, bridges, ports, and buildings. | Read Report | mdsc | |
| Transformation of Engineering Tools to Increase Material Efficiency of Concrete | Sonoko Ichimaru Watanabe, Kanotha Kamau-Devers, Patrick R Cunningham, Sabbie A Miller | Project Report | 2021 | This report demonstrates how considerations across concrete material design and infrastructure design can be used together to change environmental impacts and costs by targeting appropriate constituents, materials, and system longevity. In this early stage exploration, methods to compare concrete mixtures proportioning as they relate to environmental impacts, comparison indices based on common performance characteristics were used. | Read Report | mdsc | |
| Benchmarking GHG Emissions from California Concrete Production and Readily Implementable Mitigation Methods | Patrick R Cunningham, Sabbie A Miller | Project Report | 2021 | The demand for concrete, which is conventionally composed of granular rocks (aggregates), water, and Portland cement (as well as other additives depending on desired performance) continues to grow. The manufacturing of Portland cement leads to notable greenhouse gas (GHG) emissions, which has driven interest in alternative concrete mixture designs, cement production processes, and other emissions mitigation strategies. | Read Report | mdsc | |
| Benchmarking GHG Emissions from California Concrete and Readily Implementable Mitigation Methods | Patrick R Cunningham, Sabbie A Miller | Project Report | 2021 | The demand for concrete, which is conventionally composed of granular rocks (aggregates), water, and Portland cement (as well as other additives depending on desired performance) continues to grow. The manufacturing of Portland cement leads to notable greenhouse gas (GHG)emissions, which has driven interest in alternative concrete mixture designs, cement production processes, and other emissions mitigation strategies. | Read Report | mdsc | |
| Achieving net zero greenhouse gas emissions in the cement industry via value chain mitigation strategies | Sabbie A Miller, Guillaume Habert, Rupert J Myers, John T Harvey | Peer-reviewed Article | One Earth | 2021 | Cement is used globally in construction materials for nearly all civil infrastructure systems supporting improved quality of life, and there is currently no substitute that can meet its functional capacity. The magnitude of cement production leads to more than 7% of annual anthropogenic greenhouse gas (GHG) emissions, resulting from both energy use and chemical reactions, which imposes a notable barrier to reach net zero emissions by 2050. | Read Report | mdsc |
| Opportunities and challenges for engineering construction materials as carbon sinks | Sabbie A Miller, Elisabeth Van Roijen, Patrick Cunningham, Alyson Kim | Project Report | 2021 | Population growth and urbanization over the coming decades are anticipated to drive unprecedented demand for infrastructure materials and energy resources. Unfortunately, factors such as the degree of resource consumption, the energy-intensive nature of production, and the chemical-reaction driven emissions make infrastructure materials production industries among the greatest contributors to anthropogenic CO2 emissions. | Read Report | mdsc | |
| Environmental impacts and environmental justice implications of supplementary cementitious materials for use in concrete | Leah Brinkman, Sabbie A Miller | Peer-reviewed Article | Environmental Research: Infrastructure and Sustainability | 2021 | As the second most used material after water and the producer of 8%–9% of anthropogenic greenhouse gas (GHG) emissions, concrete is a key target for environmental sustainability efforts. Of these efforts, a main focus has been the use of industrial byproducts as supplementary cementitious materials (SCMs) to replace some of the cement binder, the source of most of the GHG emissions from concrete production. | Read Report | mdsc |
| Utilization of post-consumer carpet calcium carbonate (PC4) from carpet recycling as a mineral resource in concrete | Patrick R Cunningham, Peter G Green, Sabbie A Miller | Peer-reviewed Article | Resources, Conservation and Recycling | 2021 | The short residence time of certain building materials, such as carpets, results in a notable waste stream that has the potential to be a resource for other material systems. In this work, we explore the utilization of post-consumer carpet calcium carbonate (PC4) consisting primarily of the material from carpet backing, which has thus far found few markets, as a potential mineral admixture in the production of concrete. | Read Report | mdsc |
| The role of data variability and uncertainty in the probability of mitigating environmental impacts from cement and concrete | Sabbie A Miller | Peer-reviewed Article | Environmental Research Letters | 2021 | Concrete is the most produced manmade material globally. This widespread production results in significant anthropogenic environmental impacts, the awareness of which has spurred advances in material development to lower these burdens. | Read Report | mdsc |
| US industrial sector decoupling of energy use and greenhouse gas emissions under COVID: durability and decarbonization | Sabbie A Miller, Emily Grubert | Peer-reviewed Article | Environmental Research Communications | 2021 | The 2020 response to the coronavirus pandemic has had a profound and rapid effect on social behavior, the economy, and consumption. Associated declines in greenhouse gas (GHG) emissions have prompted calls to action to use the pandemic experience to accelerate decarbonization. | Read Report | mdsc |
| Effects of Leaching Method and Ashing Temperature of Rice Residues for Energy Production and Construction Materials | Patrick R Cunningham, Li Wang, Peter Thy, Bryan M Jenkins, Sabbie A Miller | Peer-reviewed Article | ACS Sustainable Chemistry & Engineering | 2021 | Escalating demands for infrastructure materials and energy worldwide necessitate exploration of means to efficiently utilize resources to support growing consumption. This work evaluates the potential symbiotic relationship between cultivation of an agricultural product (namely, rice), energy conversion, and utilization of bioash in the production of cement-based materials to improve the sustainability across multiple industries. | Read Report | mdsc |
| Using internal micro-scale architectures from additive manufacturing to increase material efficiency | Kanotha Kamau-Devers, Valerie R Yanez, Van Willem Medina Peralta, Sabbie A Miller | Peer-reviewed Article | Journal of Cleaner Production | 2021 | Several strategies have been posed to mitigate environmental burdens from plastics manufacturing. Two growing areas of exploration have been the use of bio-derived plastics and the use of material efficiency principles to reduce overall plastics demand. Bio-derived plastics are typically considered to be more environmentally sustainable than their petroleum-based counterparts. | Read Report | mdsc |
| Circularity of Lithium-Ion Battery Materials in Electric Vehicles | Jessica Dunn, Margaret Slattery, Alissa Kendall, Hanjiro Ambrose, and Shuhan Shen | Peer-reviewed Article | Environmental Science & Technology | 2021 | Batteries have the potential to significantly reduce greenhouse gas emissions from on-road transportation. However, environmental and social impacts of producing lithium-ion batteries, particularly cathode materials, and concerns over material criticality are frequently highlighted as barriers to widespread electric vehicle adoption. Circular economy strategies, like reuse and recycling, can reduce impacts and secure regional supplies. | Read Article | |
| Microhabitats associated with solar energy development alter demography of two desert annuals | Karen E. Tanner, Kara A. Moore‐O’Leary, Ingrid M. Parker, Bruce M. Pavlik, Sophia Haji, Rebecca R. Hernandez | Peer-reviewed Article | Ecological Applications | 2021 | Political and economic initiatives intended to increase energy production while reducing carbon emissions are driving demand for solar energy. Consequently, desert regions are now targeted for development of large‐scale photovoltaic solar energy facilities. Where vegetation communities are left intact or restored within facilities, ground‐mounted infrastructure may have negative impacts on desert‐adapted plants because it creates novel rainfall runoff and shade conditions. | Read Article | |
| Towards Building Decarbonization: Lessons From Affordable Housing Pioneers | Outcault, Sarah; Sanguinetti, Angela; Alston-Stepnitz, Eli | Presentation | Behavior, Energy, and Climate Change Conference | 2020 | This presentation highlights preliminary findings about stakeholder experience developing, operating and maintaining various types of decarbonized affordable housing. | Presentation Slides | mtrp |
| Towards a Better Understanding of Non-Energy Impacts Associated with Residential Energy Retrofit Projects | Dessouky, N., Outcault, S. & A. Sanguinetti. | Conference Paper | ACEEE Summer Study on Energy Efficiency in Buildings | 2020 | This paper explores the limitations of methods used by studies on non-energy impacts of energy retrofit projects, and outlines an approach that facilitates more robust comparisons. | Read Paper | mtrp |
| Connected thermostats for low income households: Insights from user testing | Alston-Stepnitz, E., Sanguinetti, A., Peffer, T., & Outcault, S. | Conference Paper | ACEEE Summer Study on Energy Efficiency in Buildings | 2020 | This paper describes key findings from user testing of a connected thermostat designed for low-income households. | Read Paper | mtrp |
| Improving Ventilation and Indoor Environmental Quality in California Schools | Theresa Pistochini, Caton Mande, Mark Modera, Sarah Outcault, Angela Sanguinetti | Project Report | 2020 | This project developed and demonstrated approaches to synergistically improve ventilation and indoor environmental quality during replacements of packaged heating, ventilation, and air conditioning (HVAC) systems in California schools. | Read Report | mtrp | |
| The Landscape of Residential Solar Water Heating in California | Mithra Moezzi, Aaron Ingle, Loren Lutzenhiser | Project Report | 2020 | Despite the long history of solar thermal water heating, the literature on its use is scattered, siloed, and uneven in coverage. This report outlines the “landscape” of solar water heating for single-family residences in California, covering technologies, the supply chain and marketplace, households as purchasers and users, and data sources. | Download | mtrp | |
| An Experimentally Validated Model of a Cross-Flow Sub-Wet Bulb Evaporative Chiller | Yahui Yang, Vinod Narayanan, Theresa Pistochini, Derrick Ross | Peer-reviewed Article | Thermal Science and Engineering Applications | 2020 | A simplified model to predict the performance of a novel sub-wet bulb evaporative chiller (SWEC) for producing chilled water is presented. The SWEC design uses a daisy-chained arrangement of cross-flow heat exchangers (HXs) with evaporative media located in between the heat exchangers to chill water below the outdoor wet bulb temperature (WB) in either a one-pass or two-pass arrangement. | Read Report | wcec |
| Testing, Adjusting and Balancing HVAC Systems: An Overview of Certification Agencies | Fredrick Meyers, Theresa Pistochini | Project Report | 2020 | In this report, we examine the benefits of using a certified contractor for TAB and describe the three main certifying agencies and differences between them. | Download | wcec | |
| Transient simultaneous heat and mass transfer model to estimate drying time in a wetted fur of a cow | Elizabeth Chen, Vinod Narayanan, Theresa Pistochini, Erfan Rasouli | Peer-reviewed Article | Biosystems Engineering | 2020 | To reduce heat stress that contributes to complications in milk production and breeding, dairy cows are typically cooled by intermittent water sprays coupled with fan-induced air flow. Industry currently utilises fixed duration on and off-cycles; however, water efficiency may be improved by matching the sprinkler off-time to the cow drying time that corresponds to current outdoor environmental conditions. Electricity use can also be reduced by varying fan speeds to achieve the required heat rejection rate for a given set of conditions. To achieve savings in water and electricity, a transient, one-dimensional simultaneous heat and mass transfer model of evaporation within the wetted fur layer of a dairy cows was developed to estimate drying time and heat rejection rate based on ambient conditions. | Read Article | wcec |
| Techno-economic parametric analysis of large diameter shallow ground heat exchanger in California climates | Antash Najib, Angelo Zarrella, Vinod Narayanan, Richard Bourne, Curtis Harrington | Academic Journal Paper | 2020 | A parametric study of a large diameter, shallow bore ground heat exchanger system coupled to a water-to-air heat pump is presented. The performance of this system is compared to an equivalent air-to-air heat pump system. Building loads from a single-family home in two different climate zones with different magnitudes and ratio of winter and heating loads are used in this study. In the first climate zone (Sacramento, CA), the winter load is two times the summer load while in the second climate zone (Riverside, CA), the winter and heating loads are nearly balanced. | Read Article (paywall) | wcec | |
| Analysis of Greenhouse Gas Emissions from Residential Heating Technologies in the USA | Nelson Dichter, Aref Aboud | Technical Report | 2020 | Greenhouse gases (GHGs) are a group of compounds that have a high transmittance of most electromagnetic wavelengths of solar radiation but low transmittance of infrared (heat) radiation. The earth is continuously heated by solar radiation from the sun and cooled by emitting infrared radiation to the sky. When higher levels of GHGs are present in the atmosphere, more of the radiation being emitted by the earth is reflected back on its surface rather than escaping into space while solar radiation is still able to penetrate the atmosphere. | Read Report | wcec | |
| Analysis of Greenhouse Gas Emissions Reductions Using Functional Storage Options in California | Nelson Dichter | Technical Report | 2020 | This research investigates the potential impact thermal energy storage systems can have on greenhouse gas (GHG) emissions by shifting the electric load associated with vapor-compression systems from peak to off-peak hours. | Download | wcec | |
| Performance Evaluation of a Residential Indirect-Direct Evaporative Cooler (IDEC) | Curtis Harrington, Derrick Ross | Project Report | 2020 | The purpose of this project was to conduct laboratory testing of a residential Indirect-Direct Evaporative Cooler (IDEC) to characterize its performance across typical cooling season weather conditions in climate zones 7 and 10. This technology provides cooling very efficiently using only two sets of fans and water pumps. Relying on evaporative cooling eliminates the need for high global warming potential refrigerants, and the associated compressor which consumes much of the electricity used by a traditional air conditioner. | Download | wcec | |
| Analysis of NOx Emissions from Hybrid Heating Technologies in California | Nelson Dichter | Project Report | 2020 | Nitrogen oxides (NOx), harmful and toxic greenhouse gases, are released when gas is burned at high heat in a furnace. Whole-building annual energy simulations were conducted using EnergyPLus to estimate NOx annual emissions from low NOx furnaces (40 ng/J), ultra-low NOx (14 ng/J) furnaces and hybrid heating systems (a heat pump with a low NOx furnace for auxiliary heat) in single-family residential buildings in California. Carbon dioxide (CO2) emissions were also estimated for these systems. When the results were averaged across California, weighted by the population in each California climate zone, the hybrid heating system reduced NOx emissions by 95% 100% and CO2 emissions by 67%-69% compared to a low NOx furnace. | Download | wcec | |
| Ventilation rates in California classrooms: Why many recent HVAC retrofits are not delivering sufficient ventilation | Wanyu R.Chan, Xiwang Li, Brett C.Singer, Theresa Pistochini, David Vernon, Sarah Outcault, Angela Sanguinetti, Mark Modera | Academic Journal Paper | 2020 | Previous research has shown that under-ventilation of classrooms is common and negatively impacts student health and learning. To advance understanding of contributing factors, this study visited 104 classrooms from 11 schools that had recently been retrofitted with new heating, ventilation, and air-conditioning (HVAC) units. CO2 concentration, room and supply air temperature and relative humidity, and door opening were measured for four weeks in each classroom. | Download (Paywall) | wcec | |
| Load shifting at wastewater treatment plants: A case study for participating as an energy demand resource | Erin Musabandesu, Frank Loge | Peer-reviewed Article | Elsevier | 2020 | Energy load shifting can allow for increased renewable energy integration and reduced greenhouse gas intensity of the electricity grid. Recent research has demonstrated that wastewater treatment plants have considerable potential to shift energy loads and act as energy demand resources due to their energetic flexibility and energy production capacity. This paper investigates a wastewater treatment plant in Santa Rosa, California, participating as a demand resource on the wholesale energy market through the proxy demand resource program. | Download (Paywall) | cwee |
| The cost-effectiveness of energy savings through water conservation: a utility-scale assessment | Edward Spang, Soraya Manzor, Frank Loge | Peer-reviewed Article | Environmental Research Letters | 2020 | In a previous study, the energy savings linked to a statewide water conservation mandate in California were found comparable in both resource savings as well as cost-effectiveness to the energy savings achieved directly through energy efficiency programs. This study pursues a similar line of inquiry, but at the scale of an individual city as opposed to a statewide assessment. | Download | cwee |
| Spillovers from Behavioral Interventions: Experimental Evidence from Water and Energy Use | Katrina Jessoe, Gabriel Lade, Frank Loge, Edward Spang | Peer-reviewed Article | University of Chicago Press Journals | 2020 | This paper provides experimental evidence that behavioral interventions spill over to untreated sectors by altering consumer choice. | Download (Paywall) | cwee |
| Water-energy-food security: A Nexus perspective of the current situation in Latin America and the Caribbean | Jürgen Mahlknecht, Ramón González-Bravo, Frank Loge | Peer-reviewed Article | Elsevier | 2020 | To attain sustainable development in Latin Ameica and the Caribbean, where there is a strong dependence on commodity and food price development, priority attention towards energy, water, and food security is critical. In this literature and data analysis, we examined the baseline and trends of resource security based on the Water-Energy-Food Nexus concept. | Download (Paywall) | cwee |
| Environmental impacts and decarbonization strategies in the cement and concrete industries | G Habert, SA Miller, VM John, JL Provis, A Favier, A Horvath, KL Scrivener | Peer-reviewed Article | Nature Reviews Earth & Environment | 2020 | The use of cement and concrete, among the most widely used man-made materials, is under scrutiny. Owing to their large-scale use, production of cement and concrete results in substantial emission of greenhouse gases and places strain on the availability of natural resources, such as water. | Read Report | mdsc |
| Quantitative Assessment of Alkali-Activated Materials: Environmental Impact and Property Assessments | Patrick R Cunningham, Sabbie A Miller | Peer-reviewed Article | Journal of Infrastructure Systems | 2020 | This study compares greenhouse gas (GHG) emissions, embodied energy, and air pollutant emissions of alkali-activated mortars and conventional portland cement (PC)-based mortars. Alkali-activated materials (AAMs) do not require the use of PC to offer cementitious properties; these materials can valorize industrial waste streams and noncementitious natural resources. | Read Report | mdsc |
| Life cycle environmental impact considerations for structural concrete in transportation infrastructure | SA Miller | Peer-reviewed Article | Pavement, Roadway, and Bridge Life Cycle Assessment 2020 | 2020 | Growing demand for infrastructure and its maintenance is resulting in a spike in concrete demand. Concrete is composed of several constituents, including granular rocks (aggregates), water, and cement. Conventional cement contains ground clinker, a kilned and quenched material with notable energy-derived and process-derived greenhouse gas (GHG) emissions. | Read Report | mdsc |
| The environmental attributes of wood fiber composites with bio-based or petroleum-based plastics | Kanotha Kamau-Devers, Sabbie A Miller | Peer-reviewed Article | The International Journal of Life Cycle Assessment | 2020 | While bio-based composites (bio-based plastics reinforced with natural fibers) have been discussed as potential sustainable alternatives to petroleum-based plastic composites, there are few quantitative environmental impact assessments of these materials. | Read Report | mdsc |
| Technologies and policies to decarbonize global industry: Review and assessment of mitigation drivers through 2070 | Jeffrey Rissman, Chris Bataille, Eric Masanet, Nate Aden, William R Morrow III, Nan Zhou, Neal Elliott, Rebecca Dell, Niko Heeren, Brigitta Huckestein, Joe Cresko, Sabbie A Miller, Joyashree Roy, Paul Fennell, Betty Cremmins, Thomas Koch Blank, David Hone, Ellen D Williams, Stephane de la Rue du Can, Bill Sisson, Mike Williams, John Katzenberger, Dallas Burtraw, Girish Sethi, He Ping, David Danielson, Hongyou Lu, Tom Lorber, Jens Dinkel, Jonas Helseth | Peer-reviewed Article | Applied Energy | 2020 | Fully decarbonizing global industry is essential to achieving climate stabilization, and reaching net zero greenhouse gas emissions by 2050–2070 is necessary to limit global warming to 2 °C. This paper assembles and evaluates technical and policy interventions, both on the supply side and on the demand side. | Read Report | mdsc |
| Climate and health damages from global concrete production | Sabbie A Miller, Frances C Moore | Peer-reviewed Article | Nature Climate Change | 2020 | Growing infrastructure needs worldwide have created an unprecedented demand for concrete. Its production results in high GHG emissions, the primary focus of research and mitigation strategies in the sector. However, emissions of air pollutants and the economic burden of resultant health consequences are not yet known. | Read Report | mdsc |
| The role of cement service-life on the efficient use of resources | Sabbie A Miller | Peer-reviewed Article | Environmental Research Letters | 2020 | The high demand for cement-based materials to support building and infrastructure systems is of growing concern as the production of cement leads to significant greenhouse gas (GHG) emissions and notable resource demand. While improved efficiency of cement use has been proposed as a means to mitigate these burdens, the effects of increasing longevity of cement in-use remains a poorly studied area. | Read Report | mdsc |
| Aligning Climate Change and Sustainable Development Goals With an Innovation Systems Roadmap for Renewable Power | Rebecca R. Hernandez, Sarah M. Jordaan, Ben Kaldunski and Naresh Kumar | Peer-reviewed Article | Frontiers in Sustainability | 2020 | A global energy transition from fossil fuels to renewable energy may mitigate climate change but may also undermine the capacity to achieve some or all 17 Sustainable Development Goals (SDGs). In this study, we use an innovation systems approach to construct a comprehensive roadmap for solar and wind energy to anticipate and improve impacts of a transition to a low carbon future in a manner ensuring climate goals and SDGs are mutually reinforcing. | Download (Paywall) | wild |
| Reduced ecosystem services of desert plants from ground-mounted solar energy development | Steven M. Grodsky, Rebecca R. Hernandez | Peer-reviewed Article | Nature Sustainability | 2020 | Deserts are prioritized as recipient environments for solar energy development; however, the impacts of this development on desert plant communities are unknown. Desert plants represent long-standing ecological, economic and cultural resources for humans, especially indigenous peoples, but their role in supplying ecosystem services (ESs) remains understudied. We measured the effect of solar energy development decisions on desert plants at one of the world’s largest concentrating solar power plants. | Read Article | wild |
| Simulated solar panels create altered microhabitats in desert landforms | Tanner, Karen E; Moore‚ O'Leary, Kara A; Parker, Ingrid M; Pavlik, Bruce M; Hernandez, Rebecca R; | Project Report | Ecological Society of America Journal | 2020 | Solar energy development is a significant driver of land use change worldwide, and desert ecosystems are particularly well suited to energy production because of their high insolation rates. Deserts are also characterized by uncertain rainfall, high species endemism, and distinct landforms that vary in geophysical properties. Weather and physical features that differ across landforms interact with shade and water runoff regimes imposed by solar panels, creating novel microhabitats that influence biotic communities. Endemic species may be particularly affected because they often have limited distributions, narrow climatic envelopes, or specialized life histories. | Download | |
| The Land Sparing, Water Surface Use Efficiency, and Water Surface Transformation of Floating Photovoltaic Solar Energy Installations | Alexander Cagle, Alona Armstrong, Giles Exley, Steven Grodsky, Jordan Macknick, John Sherwin and Rebecca Hernandez | Peer-reviewed Article | sustainability | 2020 | Floating photovoltaic solar energy installations (FPVs) represent a new type of water surface use, potentially sparing land needed for agriculture and conservation. However, standardized metrics for the land sparing and resource use efficiencies of FPVs are absent. These metrics are critical to understanding the environmental and ecological impacts that FPVs may potentially exhibit. Here, we compared techno-hydrological and spatial attributes of four FPVs spanning different climatic regimes. Next, we defined and quantified the land sparing and water surface use efficiency (WSUE) of each FPV. Lastly, we coined and calculated the water surface transformation (WST) using generation data at the world’s first FPV (Far Niente Winery, California). The four FPVs spare 59,555 m2 of land and have a mean land sparing ratio of 2.7:1 m2 compared to ground-mounted PVs. Mean direct and total capacity-based WSUE is 94.5 ± 20.1 SD Wm−2 and 35.2 ± 27.4 SD Wm−2, respectively. Direct and total generation-based WST at Far Niente is 9.3 and 13.4 m2 MWh−1 yr−1, respectively; 2.3 times less area than ground-mounted utility-scale PVs. Our results reveal diverse techno-hydrological and spatial attributes of FPVs, the capacity of FPVs to spare land, and the utility of WSUE and WST metrics. | Read Article | |
| Electrical Energy Storage and Energy Management System for the Sustainable City in Dubai | Park, J.W., Rahman, M., Lacap, J., Wikler, K., Outcault, S., Sanguinetti, A., Nassar, H. & A. Safwat | Project Report | 2019 | This paper examines the technical requirements for an electrical energy storage system for The Sustainable City of Dubai. | Read Report | mtrp | |
| Developer-Driven Sustainable Communities: Lessons from a Case Study of The Sustainable City in Dubai | Sanguinetti, Angela; Alan Meier; Nermin Dessouky; and Sarah Outcault | Peer-reviewed Article | European Council for an Energy Efficient Economy | 2019 | In Dubai, a private developer conceived, built, and now manages, a gated community called The Sustainable City (TSC), with more than 2,000 residents, shops, a school, and a hotel. TSC was purpose-built to consume almost no energy and be especially frugal with water, harnessing cutting-edge technologies and green building practices to promise residents both efficiency and luxury. | Read Article | mtrp |
| How South Carolina's Electric Cooperatives Build Capacity Through Multi-Level Governance | Keith Taylor, Sarah Outcault | Project Report | 2019 | Electric cooperatives serve over 40 million consumers in the United States, and have a history stretching back eight decades. Historically, the provision of high-quality electricity services at the lowest possible wholesale price to its distribution cooperative members might have proven sufficient to declare generation and transmission (G&T) cooperatives a success. But electric cooperatives‚ business and governance models are facing new pressures as distributed energy technologies evolve and emerge; consumer-member preferences shift; and the economics of electric utilities changes regarding the cost structures of nuclear, coal, natural gas, and utility-scale renewables. | Download | mtrp | |
| Solar Water Heating Assessment Project: Understanding and Improving Effectiveness for California Households | Mithra Moezzi, Aaron Ingle, Sarah Outcault, Angela Sanguinetti, Loren Lutzenhiser, Hal Wilhite, James D. Lutz, Alan Meier, and Jennifer Kutzleb | Project Report | 2019 | Solar thermal water heaters are an old technology used a century ago in California. They are now used extensively, in updated form, in many countries. According to government and industry estimates, well-functioning solar water heaters can theoretically displace 50 to 80 percent of the output of a natural gas-fueled household water heater, depending how hot water usage aligns with production and storage capacities. | Download | mtrp | |
| Market Intelligence? Eliciting valuable information from non-expert stakeholders | Outcault, S. | Presentation | Behavior, Energy, and Climate Change Conference | 2019 | Lessons from a series of stakeholder surveys and interviews on priorities for distributed energy resources are presented. | Presentation Slides | mtrp |
| A revised capacitance resistance model for large diameter shallow bore ground heat exchanger | Antash Najib, Angelo Zarrella, Vinod Narayanan, Peter Grant, Curtis Harrington | Academic Journal Paper | 2019 | Ground heat exchangers (GHE) for residential heat pumps have the advantage of rejecting (extracting) heat to a lower (higher) temperature sink (source) as compared with air source heat pumps. The thermal performance of shallow GHEs with larger diameter and of helical shape is modelled in this study using both a lumped parameter numerical model and a commercially available computational fluid dynamics (CFD) software. Measurements in a real test site single-family residence are also used for soil property calibration. | Download (paywall) | wcec | |
| Laboratory Testing of Software-Controlled Switched Reluctance Motors | Caton Mande, Matthew Stevens | Case Study | 2019 | Testing the efficacy of a high rotor pole switched reluctance motor (SRM) driven by a software-controlled inverter. | Download PDF | wcec | |
| Performance Testing of R-466A: A Low Global Warming Potential Alternative Refrigerant | Derrick Ross | Case Study | 2019 | The Western Cooling Efficiency Center (WCEC) tested the cooling performance of a unitary heat pump with R-410A and with a new, low GWP R-466A refrigerant. Researchers tested the heat pump equipment in cooling mode at six outdoor air conditions from 75°F-115°F using R-410A to obtain a baseline and repeated the tests after a drop-in replacement with the R-466A refrigerant. The cooling tests measured the total capacity, total system power, and coefficient of performance (COP) of the heat pump to determine what impact the new refrigerant had on the system’s performance. | Download | wcec | |
| Environmental impacts of alternative cement binders | Sabbie A Miller, Rupert J Myers | Peer-reviewed Article | Environmental Science & Technology | 2019 | Cement production is among the most difficult industrial activities to decarbonize. Various measures have been proposed and explored to reduce its CO2 emissions. Among these measures, the substitution of portland cement (PC) clinker with alternative materials is arguably the most effective, and consequently is an area of high research and commercial interest. | Read Report | mdsc |
| Eco-efficient design indices for reinforced concrete members | Pouria Kourehpaz, Sabbie A Miller | Peer-reviewed Article | Materials and Structures | 2019 | The production of cement, the primary binder in concrete, is resulting in notable environmental impacts worldwide. It has been argued that efficient use of cement in concrete and the efficient design of concrete components can be a means for reducing the impacts from these materials by lowering overall demand. | Read Report | mdsc |
| Hydrothermal aging of bio-based poly(lactic acid) (PLA) wood polymer composites: Studies on sorption behavior, morphology, and heat conductance | Kanotha Kamau-Devers, Zachary Kortum, Sabbie A Miller | Peer-reviewed Article | Construction and Building Materials | 2019 | This work examines the moisture sorption, the morphology, and the thermal conductivity of fully bio-based composites, namely wood flour (WF) filled poly(lactic acid) (PLA), to better understand hydrothermal deterioration and potential for long-term application. | Read Report | mdsc |
| Rice-based ash in concrete: A review of past work and potential environmental sustainability | Sabbie A Miller, Patrick R Cunningham, John T Harvey | Peer-reviewed Article | Resources, Conservation and Recycling | 2019 | The demand for concrete continues to grow with increases in population and increased urbanization. This demand, in turn, increases the need to reduce the environmental impacts of concrete while continuing to provide the same or better performance. | Read Report | mdsc |
| Energy Consumption in Campus Buildings When No One is Around | Alexander Joseph Sloan | Master's Thesis | 2019 | This study introduced a new methodology to estimate how often regularly-inhabited buildings are vacant and the electricity consumed during these times. | Read Report | ||
| Building Leakage Diagnosis Using IoT Enabled MEMS Sensors | Armando Casillas | Master's Thesis | 2019 | A new method that determines building-specific envelope and duct leakage with minimal disruption to normal building operationshas been identified. The methodology utilizes an array ofMicro Electro-Mechanical Systems (MEMS) absolute pressure, temperature and humidity sensors placed at key building and ductwork locations,and makesuse ofmass/species conservation and flow characterization equations. The “MEMS protocol”was applied to a dataset aggregated from a series of controlled tests performed over a 3-month period in a building on the UC Davis campus. | Read Report | ||
| Beyond 100% Renewable: Policy and Practical Pathways to 24/7 Renewable Energy Procurement | Gregory Miller | Peer-reviewed Article | The Electricity Journal | 2019 | Corporations are increasingly shaping the future of the electric grid by pursuing 100% renewable energy goals that seek to match their annual energy consumption with an equal volume of renewable energy. The challenge of achieving a 100% renewable electricity grid, however, is not only a question of how much renewable energy is built, but rather whether renewables can supply electricity when it is needed. One emerging approach to address this challenge is a 24/7 renewable energy which requires matching a corporation's hourly energy demand with renewable energy produced in the same region and hour. | Download | |
| Dressing for the Anthropocene | Poskanzer, Deborah, Alan Meier, Chinmayee Subban, and Margarita Kloss | Peer-reviewed Article | European Council for an Energy Efficient Economy | 2019 | As the world gets hotter, we are caught in a dilemma between the need to maintain thermal comfort, while at the same time reducing the use of air conditioning (AC) as a source of GHG emissions. AC has been, and will continue to be, a major driver of growing electricity demand. Space cooling in buildings accounts for 10% of world total electricity use and 12% of building CO2 emissions. | Read Article | |
| Emerging Zero-Standby Solutions for Miscellaneous Electric Loads and the Internet of Things | Gerber, Daniel L., Alan Meier, Richard Liou, and Robert Hosbach | Peer-reviewed Article | Electronics | 2019 | Despite technical advances in efficiency, devices in standby continue to consume up to 16% of residential electricity. Finding practical, cost-effective reductions is difficult. While the per-unit power consumption has fallen, the number of units continuously drawing power continues to grow. This work reviews a family of technologies that can eliminate standby consumption in many types of electrical plug loads. It also investigates several solutions in detail and develops prototypes. First, burst mode and sleep transistors are established as building blocks for zero-standby solutions. This work then studies the application of two types of wake-up signals. | Read Article | |
| Hare don't care! Consumption of a rare, desert milkweed containing phytochemicals by the black-tailed jackrabbit | Grodsky, Steven M; Saul-Gershenz, Leslie S; Moore-O’Leary, Kara A; Whitney, Jason P; Hernandez, Rebecca R; | Peer-reviewed Article | Journal of Arid Environments | 2019 | We recorded video providing the first conclusive evidence that the black-tailed jackrabbit (Lepus californicus) consumes Mojave milkweed (Asclepias nyctaginifolia) containing phytochemicals in the Ivanpah Valley, Mojave Desert, California, USA. We discuss possible chemical and biological interactions between the black-tailed jackrabbit and Mojave milkweed. | Download | |
| Non-Invasive Assessments of Thermal Discomfort in Real Time | Meier, Alan, Xiaogang Cheng, William Dyer, Graham Chris, Thomas Olofsson, and Bin Yang | Conference Paper | 2019 | People make distinctive gestures or movements when they are thermally uncomfortable, for example self-hugging when uncomfortably cold or brow-wiping when hot. Extreme thermal conditions reinforce this tendency. These gestures may be affected by various competing motivations such as emotional or physiological responses and cultural traditions. Several software applications can now identify and track movements of a person’s skeletal joints or keypoints in real time; these include hands, arms, elbows, head, etc.. A procedure was created to identify gestures related to thermal discomfort and then to decide if a person is uncomfortably warm or cold. When a discomfort-related gesture is detected, it is scored based on the type of gesture and recognition confidence. This score is fed into a “Thermal Comfort Index” (TCI). | Read Article | ||
| Real-time and contactless measurements of thermal discomfort based on human poses for energy efficient control of buildings | Bin Yang, Xiaogang Cheng, Dengxin Dai, Thomas Oloffsson, Haibo Li, Alan Meier | Peer-reviewed Article | Building and Environment | 2019 | Individual thermal discomfort perception gives important feedback signals for energy efficient control of building heating, ventilation and air conditioning systems. However, there is few effective method to measure thermal discomfort status of occupants in a real-time and contactless way. A novel method based on contactless measurements of human thermal discomfort status was presented. | Read Article (paywall) | |
| Renewable Energy Ecology | Grodsky, Steven M; Fritts, Sarah R; Hernandez, Rebecca R; | Book | 2019 | The progression of renewable energy enterprises and their physical manifestations (hereafter collectively referred to as ‚renewable energy development) is a critical wildlife conservation issue. This book provides a foundation on which wildlife professionals and researchers can build their understanding of renewable energy and wildlife conservation in theory and practice. | |||
| Techno-ecological synergies of solar energy for global sustainability | Hernandez, Rebecca R.; Armstrong, Alona; Burney, Jennifer; Ryan, Greer; Moore-O'leary, Kara; Di√©dhou, Ibrahima; Grodsky, Steven M.; Saul-Gershenz, Leslie; Davis, R; Macknick, Jordan; | Peer-reviewed Article | Nature | 2019 | The strategic engineering of solar energy technologies‚ from individual rooftop modules to large solar energy power plants‚ can confer significant synergistic outcomes across industrial and ecological boundaries. Here, we propose techno‚Äìecological synergy (TES), a framework for engineering mutually beneficial relationships between technological and ecological systems, as an approach to augment the sustainability of solar energy across a diverse suite of recipient environments, including land, food, water, and built-up systems. | Download | |
| Using data from connected thermostats to track large power outages in the United States | Alan Meier, Tsuyoshi Ueno, Marco Pritoni | Peer-reviewed Article | Applied Energy | 2019 | The detection of power outages is an essential activity for electric utilities. A large, national dataset of Internet-connected thermostats was used to explore and illustrate the ability of Internet-connected devices to geospatially track outages caused by hurricanes and other major weather events. The method was applied to nine major outage events, including hurricanes and windstorms. In one event, Hurricane Irma, a network of about 1,000 thermostats provided quantitatively similar results to detailed utility data with respect to the number of homes without power and identification of the most severely affected regions. The method generated regionally uniform outage data that would give emergency authorities additional visibility into the scope and magnitude of outages. The network of thermostat-sensors also made it possible to calculate a higher resolution version of outage duration (or SAIDI) at a level of customer-level visibility that was not previously available. | Download | |
| Using social dynamics to explain uptake in energy saving measures: Lessons from space conditioning interventions in Japan and California | Outcault, S., Sanguinetti, A. & M. Pritoni. | Peer-reviewed Article | Energy Research & Social Science | 2018 | This paper examines the intersection of the social attributes of cooling measures and the prevailing social dynamics within households. A game-theoretical model is developed to illustrate how the varied combinations of measure attributes and social dynamics can yield different cooling strategies across households. | Read Article | mtrp |
| Aligning Occupant Behavior with ZNE Community Goals and Assumptions: Quantifying and Leveraging Behavioral Plasticity | Angela Sanguinetti, Sarah Outcault, Alan Meier | Conference Paper | ACEEE Summer Study on Energy Efficiency in Buildings | 2018 | In residential communities designed for energy efficiency, do the occupants take an active role in conserving energy, or leave it up to the home itself? We examined cooling practices in a new, low-energy development, located in one of the hottest climates in the world. The Sustainable City (TSC) in Dubai attracts individuals from across the globe, with varying cultures, values, attitudes, and habits. TSC staff promote a culture of sustainability, but there are challenges in achieving zero net energy (ZNE). Data on household energy consumption were collected from residents and household staff through in-person interviews and an online survey. We found evidence of a wide range of occupant values and cooling strategies. Many residents came from cooler regions in the world and were unfamiliar with cooling practices and technologies in their homes. We identified opportunities to leverage behavioral plasticity - i.e., residents' capacity to shift everyday practices - to save energy. This study suggests a framework for aligning occupant behavior with the goals and values embodied in sustainably-built communities. Specifically, designers and managers of sustainable communities need to educate, motivate, and support residents in order to encourage the specific energy-conserving practices required for sustainable buildings to achieve their technical potential. | Read Article | mtrp |
| MANY SHADES OF GREEN: Establishing a Culture of Sustainability in a Diverse, Developer-Driven Expatriate Community | Dessouky, Nermin, Angela Sanguinetti, Alan Meier, Sarah Outcault, and Richard Tutwiler | Peer-reviewed Article | Community | 2018 | We are a team of researchers from The University of California, Davis, and The American University of Cairo, investigating ways to promote a culture of sustainability in planned communities. We have been studying TSC for three years and observing how the community has been evolving over time. It is our assertion that although TSC is a large-scale developer-led community, it illustrates the ways in which the intention of a community is integral to sustainable lifestyles. We will discuss how some aspects of TSC's design and management promote, or present challenges to, the community's culture of sustainability. | Read Article | mtrp |
| Laboratory and Field Testing of RTU Optimization Package Combining a Condenser-Air Pre-Cooler with Compressor Speed Reduction | Theresa Pistochini, Caton Mande | Project Report | 2018 | This report describes a laboratory and field evaluation of a retrofit package to optimize the performance and efficiency of packaged air conditioning and heating Roof Top Units (RTUs). The package included Variable-Frequency Drive(s) (VFDs) to reduce the speed of the compressor(s) to 48 Hertz (Hz), and a condenser-air pre-cooler. This retrofit package is being considered as a method to save energy associated with air conditioning at all conditions, reduce peak electricity demand, and permanently reduce load on the compressor. | Download From ETCC Website | wcec | |
| Characterizing the Transient and Aggregate Response of Dispatchable Condenser Air Pre-Coolers | Caton Mande, Derrick Ross, Robert McMurry, Theresa Pistochini | Project Report | 2018 | Evaporative condenser air pre-coolers, or “pre-coolers,” use evaporative cooling methods to pre-cool the inlet air to the condenser of an air conditioning system. This results in a lower temperature for air conditioner heat rejection, reducing power demand and increasing air conditioning process efficiency. While significant work has been done to demonstrate precoolers as an energy efficiency measure, this project studied the technology as a dispatchable demand response resource, controlled by the utility for grid management. | Download From ETCC Website | wcec | |
| Software-Controlled Switch Reluctance Motors | Theresa Pistochini, Caton Mande, Matthew Stevens | Project Report | 2018 | This project measured the performance of an emerging technology nominal threehorsepower (3HP) high rotor pole Switched Reluctance Motor (SRM) with softwarecontrolled inverter, compared to a baseline nominal 3HP baseline induction motor controlled by a Variable-Frequency Drive (VFD) in laboratory testing, and a nominal 3HP baseline single-speed induction motor for field testing. The difference in performance between the two motors was used to forecast annual energy and demand savings expected to result from replacing the baseline technology with the emerging technology. | Download From ETCC Website | wcec | |
| Using Videos to Promote Evaporative Cooling Adoption | Sarah Outcault, Paul Fortunato | Case Study | 2018 | Providing better information and communication is needed to encourage stakeholder adoption of ECTs. This WCEC study compared two methods of communicating information: outreach videos and manufacturer websites. | Download PDF | wcec | |
| Design and Performance Characterization of a Micro-pin fin sCO2 Recuperator | Cameron Naderi, Erfan Rasouli, Vinod Narayanan | Symposium Proceeding Paper | 2018 | Design, fabrication, and thermal-fluidic characterization of a compact three-layered recuperator unit cell (RUC) was presented in this study. The supercritical carbon dioxide (sCO2) streams flowed through microscale pin arrays on the hot and cold sides. A detailed design using Computational fluid dynamics (CFD) and structural analysis simulations was then performed to develop a final design of the RUC. An experimental facility was assembled to characterize the thermal-fluidic performance of the RUC. Results indicated that effectiveness of 90 percent or higher could be achieved at low approach temperatures. The correlation-based model predicted the overall heat transfer coefficient to within 20 percent of the experimental data. Based on the performance of the RUC, preliminary scaling estimated for a multiple-unit cell recuperator was also provided. | Download PDF | wcec | |
| Design and Performance Characterization of an Additively Manufactured Primary Heat Exchanger for sCO2 Waste Heat Recovery Cycles | Erfan Rasouli, Samikshya Subedi, Colt Montgomery, Caton W. Mande, Matthew Stevens, Vinod Narayanan, Anthony D. Rollett | Symposium Proceeding Paper | 2018 | Design, fabrication and characterization of an additively manufactured (AM) Inconel 718 Primary Heat Exchanger (PHX) for waste heat recovery was discussed in this paper. Design details including considerations of pressure drop on the hot side, high internal pressure on the sCO2 side and the near-counter flow design for high effectiveness were discussed. The fabricated AM PHX was pressure tested at temperature for verification of structural integrity. Preliminary results of pressure drop and heat transfer rate were also presented. | Download PDF | wcec | |
| Pitch and Aspect Ratio Effects on Single-Phase Heat Transfer through Microscale Pin Fin Heat Sinks | Erfan Rasouli, Cameron Naderi, Vinod Narayanan | Academic Journal Paper | 2018 | Heat transfer and pressure drop of single-phase liquid flow was characterized in eight micro pin fin heat sinks with varied pitch and aspect ratios. Flow visualization was performed on all the heat sinks and flow transition into unsteady vortex shedding was observed only in those with specific pitch and aspect ratios. The existence of vortex shedding in micro pin fin heat sinks enhanced the heat transfer and affected the prediction error of heat transfer correlations in literature. Separate correlations were developed to predict Nusselt number in the steady and unsteady regimes. | Download From Journal Website | wcec | |
| High Flux Thermal Receiver and Method of Use | Monte Kevin Drost, Sourabh Apte, Thomas L'estrange, Vinod Narayanan, Charles Rymal, Eric Truong, Erfan Rasouli, Kyle Ryan Zada, Brian M Fronk | US Patent Application | 2018 | A thermal receiver, such as a solar flux thermal receiver, is disclosed comprising a modular arrangement of arrayed microchannels or micropins to heat a working fluid by heat transfer. Disclosed solar receivers provide a much higher solar flux and consequently a significant reduction in thermal losses, size, and cost, relative to known receivers. Unit cell receivers can be numbered up and combined in parallel to form modules, and modules combined to form full scale receivers. | Download PDF | wcec | |
| Improving System Efficiency for a Variable-Capacity/Variable-Blower-Speed Residential Heat Pump System with Multizone Ductwork | Sreenidhi Krishnamoorthy, Mark Modera, Curtis Harrington | Academic Journal Paper | 2018 | This article describes efficiency improvements resulting from incorporating zonal airflow control into a variable-capacity/variable-fan-speed residential air-conditioning system. The results described are based on full-scale laboratory testing of prototype heat-pump equipment connected to a “typical-design” residential duct system located within a climatic chamber used to produce a range of summer climate conditions. | Download | wcec | |
| University of California Strategies for Decarbonization: Replacing Natural Gas | Alan Meier, Steven J. Davis, David G. Victor, Karl Brown, Lisa McNeilly, Mark Modera, Rebecca Zarin Pass, Jordan Sager, David Weil, David Auston, Ahmed Abdulla, Fred Bockmiller, Wendell Brase, Jack Brouwer, Charles Diamond, Emily Dowey, John Elliott, Rowena Eng, Stephen Kaffka, Carrie V. Kappel, Margarita Kloss, Igor Mezić, Josh Morejohn, David Phillips, Evan Ritzinger, Steven Weissman, Jim Williams | White Paper | 2018 | Having pledged to become carbon neutral by 2025, the University of California has embarked on a large-scale effort to evaluate options for achieving this goal. For UC, the central challenge to deep decarbonization lies in reducing and, perhaps, ultimately eliminating the use of natural gas, a fossil fuel consisting primarily of methane. Nearly all CO2 emissions (96%) from UC operations come from direct combustion of natural gas (a “Scope 1” emission) and from purchased electricity generated from fossil fuels (a “Scope 2” emission). Therefore, a cost-effective exit strategy for conventional natural gas is vital to achieving the carbon neutrality goal. The UC carbon neutrality goal does not include “Scope 3” emissions, which are other emissions indirectly related to the University’s activities, such as from gasoline burned in employee-owned vehicles. | Download | wcec | |
| Turning Paris into reality at the University of California | David G. Victor, Ahmed Abdulla, David Auston, Wendell Brase, Jack Brouwer, Karl Brown, Steven J. Davis, Carrie V. Kappel, Alan Meier, Mark Modera, Rebecca Zarin Pass, David Phillips, Jordan Sager, David Weil | Academic Journal Paper | 2018 | The Paris Agreement highlights the need for local climate leadership. The University Of California’s approach to deep decarbonization offers lessons in efficiency, alternative fuels and electrification. Bending the emissions curve globally requires efforts that blend academic insights with practical solutions. | Download | wcec | |
| Valuation of Thermal Energy Storage for Utility Grid Operators | Nelson Dichter, Michael Day, Mark Modera | Project Report | 2018 | This research investigates the potential impact on peak electric load that thermal energy storage systems can have on the electric grid by displacing vapor-compression systems and shifting the associated electric load from peak to off-peak hours. Whole building computer simulations were used to estimate the accuracy of two methods used by California utilities to quantify the value of thermal energy storage systems, the “10-Day Average Baseline” method and the “permanent load shift” method. | Download | wcec | |
| Carbon dioxide reduction potential in the global cement industry by 2050 | Sabbie A Miller, Vanderley M John, Sergio A Pacca, Arpad Horvath | Peer-reviewed Article | Cement and Concrete Research | 2018 | This paper, which is a contribution to the UNEP series on Eco-Efficient Cements, examines the role of material-based solutions to reducing CO2 emissions from cement production considering factors that could influence implementation. Global urbanization has led to an increase in demand for cement and cement-based materials. | Read Report | mdsc |
| Natural fiber textile reinforced bio-based composites: Mechanical properties, creep, and environmental impacts | Sabbie A Miller | Peer-reviewed Article | Journal of Cleaner Production | 2018 | With rising demand for construction materials, so too grow the environmental impacts associated with their production. This trend has raised interest in the development of bio-based composites as environmentally favorable alternatives to conventional materials. | Read Report | mdsc |
| Reducing greenhouse gas emissions for prescribed concrete compressive strength | Chao Fan, Sabbie A Miller | Peer-reviewed Article | Construction and Building Materials | 2018 | Often, when proportioning “green” concrete mixtures, the use of Supplementary Cementitious Materials (SCMs) is deemed to be favorable. While appearing more in the literature, it is still not commonplace that design strength is considered in assessments of environmental impacts. | Read Report | mdsc |
| Supplementary cementitious materials to mitigate greenhouse gas emissions from concrete: can there be too much of a good thing? | Sabbie A Miller | Peer-reviewed Article | Journal of Cleaner Production | 2018 | Among the many possible strategies for reducing anthropogenic greenhouse gas (GHG) emissions is reduction of emissions associated with the production of concrete, which is responsible for 8–9% of global anthropognic GHG emissions. Using supplementary cementitious materials (SCMs) in concrete to offset demand for clinker in cement is a commonly proposed method to cut GHG emissions from concrete production. | Read Report | mdsc |
| Impacts of booming concrete production on water resources worldwide | Sabbie A Miller, Arpad Horvath, Paulo JM Monteiro | Peer-reviewed Article | Nature Sustainability | 2018 | Concrete is the most-used construction material worldwide. Previous studies on the environmental impacts of concrete production have mainly focused on the materials involved and energy consumption, as well as CO2 emissions; little is known, however, about its water consumption as well as the effective measures to reduce such consumption. | Read Report | mdsc |
| WEMap: A Software Tool for Estimating Water Utility Energy Savings from Water Conservation | Edward Spang, Andrew Holguin, Frank Loge | Research Paper | 2018 | The water sector demands significant energy inputs to deliver safe and reliable water to urban communities. It follows that water conservation efforts can lead to measurable upstream reductions in energy use, as well as complementary reductions in operational costs and greenhouse gas emissions. However, the complexity of many urban water infrastructure networks produces a high level of seasonal and spatial variability of the energy embedded in the water delivered across the utility service territory. | Download | ||
| Electrifying Last Mile Deliveries: The Case of Parcel Delivery Fleets | Leticia Del Pilar Pineda Blanco | Master's Thesis | 2018 | Trucking is a key component of the freight sector, which is an important contributor to the California economy, but also contributes to externalities associated with climate and local emissions, congestion, and noise, among others. This work assesses alternative technologies using real driving data for parcel delivery fleets and evaluates the role of monetary incentives in California. | Read Report | ||
| Hydrogen Energy Storage for Renewable-Intensive Electricity Grids: A WECC Case Study | Zane Logan McDonald | Master's Thesis | 2018 | This research project investigates the feasibility and energy system costs and benefits of hydrogen energy storage (HES) integrated with the electricity grid. This analysis aims to illuminate the impacts of responsive water electrolysis in high-renewable penetration electricity grids to convert renewable electricity into low-carbon hydrogen. This process has the potential to help balance the electric grid while providing an energy carrier that could be used in diverse energy applications. | Read Report | ||
| Builder-Installed Electrical Loads: Parts of the House That Stay On and On | Meier, Alan; Leo Rainer; and Aditya Khandekar | Peer-reviewed Article | Home Energy | 2018 | Not too many years ago, when you unplugged all the appliances in a home the doorbell transformer was the only device still drawing power. That is no longer true‚ as a host of devices now draw power before anybody moves in. The most common devices include ground fault circuit interrupters (GFCIs), garage door openers, and hardwired smoke alarms. | Read Article | |
| Climate Change and Garage Door Openers | Meier, Alan | Other | Home Energy | 2018 | California just approved legislation requiring all new garage door openers to have battery backups, so that doors would open even when electricity service is interrupted. The legislation SB 969 sailed through with almost no opposition. Curiously, the only group to oppose the bill was the industry responsible for garage doors, the people most likely to benefit from it. What is going on here, and what does this have to do with climate change and home energy? More than you might imagine. | Read Article | |
| Everyone Has a Peer in the Low User Tier: The Diversity of Low Residential Energy Users | Deumling, Reuben, Deborah Poskanzer, and Alan Meier | Peer-reviewed Article | Energy Efficiency | 2018 | Low residential energy use is typically associated with undesirable characteristics, such as poverty, thermal discomfort, or small dwelling size. The association of low energy use with deprivation has been an obstacle to promoting more aggressive goals for reduction of residential use. However, there is little research on the composition of the low user population. We investigated the demographics, behavior, and satisfaction of the lowest 10% of electricity consumers in Sacramento, CA, to see what attributes best correlated with low use. | Read Article | |
| Hydrogen Energy Storage for Renewable-Intensive Electricity Grids: A WECC Case Study | Zane McDonald | Master's Thesis | 2018 | Electricity grid operation requires balancing supply and demand for electricity on a continuous basis. The primary option for dealing with the variability in renewable energy generation is to maintain a significant capacity of backup/standby peak generation. Still, offpeak renewable electric production is sometimes curtailed because it cannot be economically used or captured. Low cost, efficient energy storage could enable optimized allocation of intermittent electric generation resources to high-value markets. This research project investigates the feasibility and energy system costs and benefits of hydrogen energy storage (HES) integrated with the electricity grid. | Download | ||
| Solar Energy Development and the Biosphere | Murphy-Mariscal, Michelle; Grodsky, Steven M; Hernandez, Rebecca R; | Peer-reviewed Article | A Comprehensive Guide to Solar Energy Systems | 2018 | Although solar energy can undoubtedly contribute to global deep decarbonization and mitigation of climate change through emissions reductions, the potential for ecological impacts from large installations on the ground merits further discussion. Solar energy development, particularly large and ground-mounted solar energy installations in natural or other types of environments with biophysical capacity may function as a contemporary, anthropogenic driver of disturbance and land-use and land-cover change. | Read Paper | |
| Occupant Thermal Feedback for Improved Efficiency in University Buildings | Marco Pritoni, Kiernan Salmon, Angela Sanguinetti, Joshua Morejohn, Mark Modera | Peer-reviewed Article | Energy and Buildings | 2017 | Heating, Ventilation, and Air Conditioning (HVAC) systems are responsible for more than half of the energy consumed in many buildings on university campuses in the US. Despite the significant amount of energy spent on HVAC operations, thermal comfort conditions in campus buildings are frequently poor. Faulty assumptions or a lack of data regarding occupant comfort can lead to energy waste from overheating or overcooling. Additionally, inadequate operational procedures and outdated technology make it difficult for occupant needs to inform temperature management. For example, campuses frequently use work order systems to manage temperature issues, but this process is slow and not widely used by students, i.e., the majority of building occupants. | Read Article (paywall) | mtrp |
| Upscaling Participatory Thermal Sensing: Lessons from an Interdisciplinary Case Study at University of California for Improving Campus Efficiency and Comfort | Angela Sanguinetti, Marco Pritoni, Kiernan Salmon, Alan Meier, Joshua Morejohn | Peer-reviewed Article | Energy Research &Social Science | 2017 | Heating, Ventilation, and Air Conditioning (HVAC) is responsible for most of the energy consumed in many university buildings, which are still often uncomfortable for occupants. Previous research suggests crowdsourcing thermal comfort feedback from occupants, called participatory thermal sensing (PTS), and incorporating it into the HVAC control system can improve energy efficiency and comfort simultaneously. Most PTS research has focused on automated closed-loop systems whereby occupant feedback is automatically integrated into HVAC operations, but such systems are difficult to scale. | Download | mtrp |
| Teacher knows best? Balancing energy savings, air quality, and comfort in California’s schools | Outcault, S. | Presentation | Behavior, Energy, and Climate Change Conference | 2017 | Summarizes findings from a teacher survey on classroom air quality. | Presentation Slides | mtrp |
| Efficiency optimization of a variable-capacity/variable-blower-speed residential heat-pump system with ductwork | Sreenidhi Krishnamoorthy, Mark Modera, Curtis Harrington | Academic Journal Paper | 2017 | The purpose of this study was to evaluate the cooling operation of a variable-capacity/variable-fan-speed residential heat-pump connected to a typical single-zone duct system located outside the conditioned space in a hot-dry climate. This was accomplished through full-scale laboratory testing of prototype heat-pump equipment connected to a complete residential duct system within a climatic chamber wherein a range of summer conditions were simulated. Compressor speeds and evaporator airflows were manipulated over a range of practical combinations to characterize the efficiency of the entire system. | Download From Journal Website | wcec | |
| Phase-Change Heat Transfer Characterization In Microscale-pin fin Heat Sinks | Erfan Rasouli, Vinod Narayanan | Academic Journal Paper | 2017 | Subcooled and saturated flow boiling of Performance Fluid PF5060 through four micro pin fin heat sinks (μPFHSs) with varied pitch and aspect ratios was investigated in this study. The phenomenon of vortex shedding observed in single phase flows for the higher pitch ratio heat sinks was seen to result in increased two-phase heat transfer coefficients in the nucleate boiling dominant regime. Additionally, the unsteady vortex shedding eliminated the wall temperature overshoot in the range of experiments performed. | Download From Journal Website | wcec | |
| Laboratory Testing of an Energy Efficient Dehumidifier for Indoor Farms | Theresa Pistochini, Robert McMurry, Derrick Ross, Paul Fortunato | Case Study | 2017 | Traditional dehumidification systems provide dehumidification and increase the air temperature, as opposed to the desired dehumidification and reduction of air temperature. An alternative is MSP Technology’s dehumidification system that uses a plate air-to-air heat exchanger and a cooling coil that is part of a split compressor-based refrigeration system. | Download PDF | wcec | |
| Energy-Efficient Clothes Dryers: Automatic Cycle Termination Controller | Theresa Pistochini, Caton Mande | Case Study | 2017 | This project developed an automatic dryer cycle termination controller that utilized the relationship between dryer drum inlet temperatures and outlet temperatures to accurately predict the end of the drying cycle. The technology promises to be more accurate and robust in performance under different load and environmental conditions in comparison to existing technology. The low-cost automatic controller was demonstrated in the laboratory to reduce energy use in gas clothes dryers by accurately terminating the drying cycle. In addition, information obtained in the drying cycle can be used to predict real-time energy efficiency metrics to track dryer performance over time as a means for fault detection and to provide information to the consumer. | Download PDF | wcec | |
| Performance Testing of DR-55 As A Replacement for R-410A Refrigerant | Curtis Harrington | Case Study | 2017 | One part of that solution is to reduce the global warming potential of the refrigerants used in these systems. Accidental release of refrigerant to the atmosphere is inevitable with these systems so it is imperative to identify a working fluid that has low GWP while also achieving acceptable performance and low safety risk to occupants. The predominant refrigerant used in air conditioning equipment today is R-410A. While R-410A provided a good alternative to R-22, recent advances in refrigerant blends are showing further reductions in global warming potential, while also demonstrating comparable performance. | Download PDF | wcec | |
| Towards sustainable concrete | PJM Monteiro, SA Miller, A Horvath | Peer-reviewed Article | Nature Materials | 2017 | Paulo J. M. Monteiro, Sabbie A. Miller and Arpad Horvath provide an overview of the challenges and accomplishments in reducing the environmental burden of concrete production. | Read Paper (Paywall) | mdsc |
| Energy Efficiency Measures in Affordable Zero Net Energy Housing: A Case Study of the UC Davis 2015 Solar Decathlon Home | Payman Alemi and Frank Loge | Peer-reviewed Article | Elsevier | 2017 | The 2015 UC Davis Solar Decathlon Team designed and constructed an affordable zero net energy prototype home for California (CA) farmworkers. Each major energy-efficient feature of the home was separately analyzed to gauge its energy savings impact. | Download (Paywall) | |
| Allometric equations and carbon stocks in tree biomass of Jatropha curcas L. in Senegal’s Peanut Basin | Diédhiou, I; Diallo, D; Mbengue, A; Hernandez, RR; Bayala, R; Diéme, R; Diédhiou, PM; Sène, A; | Peer-reviwed Journal Article | Global Ecology and Conservation | 2017 | In Senegal, numerous initiatives exist to cultivate Jatropha curcas L. (JCL) trees as a multipurpose energy crop, including for fuel. Thus, research on this drought-resistant shrub has been predominately focused on biofuel production from its seeds, while its potential for carbon (C) sequestration, which could be valuable in sink projects (i.e., afforestation, reforestation) under the Clean Development Mechanism (CDM) of the Kyoto protocol, has been largely unstudied. This study was carried out in Senegal’s Peanut basin to develop allometric equations for estimating biomass of individual JCL shrubs, JCL plantations, and determining their respective C storage potential. We discovered a three-stage evolution of JCL biomass accumulation. | Read Paper | |
| From butterflies to Bighorns: Multi-dimensional species-species and species-process interactions may inform sustainable solar energy development in desert ecosystems | Grodsky, Steven M; Moore-O‚ÄôLeary, Kara A; Hernandez, Rebecca R; | Peer-reviewed Article | 2017 | Favorable environmental conditions and abundant public lands (eg, Bureau of Land Management) may make deserts of the southwest United States the ideal recipient environment for solar energy development (BLM 2012, Hernandez et al. 2015). Although solar energy may help advance decarbonization, sensitive desert ecosystems may be imperiled by solar energy development (Lovich and Ennen 2011). For example, construction of solar facilities creates a series of biophysical disturbances, including grading of soils and vegetation removal, which in turn may affect biota via a bottom-up‚ trophic interactions (eg, degraded soils‚Üdecreased plant growth‚ reduced food and cover for wildlife; Hernandez et al. 2014b). Meanwhile, aridland Southwest ecosystems support exceptional biodiversity and many endemic, threatened and endangered species already stressed by climate change (Lovich and Bainbridge 1999, Mittermeier et al. 2001). | Read Paper | ||
| Land-Sparing Opportunities for Solar Energy Development in Agricultural Landscapes: A Case Study of the Great Central Valley, CA, United States | Hoffacker, Madison K; Allen, Michael F; Hernandez, Rebecca R; | Case Study | ACS Journal | 2017 | Land-cover change from energy development, including solar energy, presents trade-offs for land used for the production of food and the conservation of ecosystems. Solar energy plays a critical role in contributing to the alternative energy mix to mitigate climate change and meet policy milestones; however, the extent that solar energy development on nonconventional surfaces can mitigate land scarcity is understudied. Here, we evaluate the land sparing potential of solar energy development across four nonconventional land-cover types: the built environment, salt-affected land, contaminated land, and water reservoirs (as floatovoltaics), within the Great Central Valley (CV, CA), a globally significant agricultural region where land for food production, urban development, and conservation collide. | Read Case Study | |
| Sustainability of utility‚Äêscale solar energy‚Äìcritical ecological concepts | Moore‚O'Leary, Kara A; Hernandez, Rebecca R; Johnston, Dave S; Abella, Scott R; Tanner, Karen E; Swanson, Amanda C; Kreitler, Jason; Lovich, Jeffrey E; | Peer-reviewed Article | 2017 | Renewable energy development is an arena where ecological, political, and socioeconomic values collide. Advances in renewable energy will incur steep environmental costs to landscapes in which facilities are constructed and operated. Scientists-including those from academia, industry, and government agencies-have only recently begun to quantify trade-off in this arena, often using ground-mounted, utility-scale solar energy facilities (1 megawatt) as a model. Here, we discuss five critical ecological concepts applicable to the development of more sustainable USSE with benefits over fossil-fuel-generated energy. | Read Paper | ||
| Can you take the heat? A cross-national comparison of thermal comfort strategies and energy-saving field experiments | Outcault, S. Pritoni, M., Heinemeier, K., and A. Mikami. | Conference Paper | ACEEE Summer Study on Energy Efficiency in Buildings | 2016 | This paper presents the findings of a pair of randomized control trial to encourage the use of passive cooling techniques in Japan and the U.S. | Download Paper | mtrp |
| Assessing Players, Products, and Perceptions of Home Energy Management | Rebecca Ford; Beth Karlin; Angela Sanguinetti; Anna Nersesyan; Marco Pritoni | Project Report | 2016 | The technologies that make up Home Energy Management Systems (HEMS), providing users with information, feedback and/or control of household energy usage, are developing in a rapidly growing market within the broader smart home and Internet of Things (IoT) space. As developments create more and more energy saving products with increasing functionality, new strategies must be developed for engaging with end-users (both before adoption and after) in order to fully leverage these technologies for the energy reduction and load shifting capabilities they offer. | Download | mtrp | |
| How Do Small Businesses Experience Energy Reports? | Laura Cornish, Beth Karlin, Angela Sanguinetti, Jason Kaufman | Conference paper | ACEEE Summer Study on Energy Efficiency in Buildings | 2016 | How do small businesses experience energy reports that benchmark their performance relative to similar businesses and provide recommendations to save energy? There is a large body of research focused on energy feedback in the residential sector, but significantly less in the commercial sector. Studies in both sectors have focused on the effectiveness of feedback in terms of savings outcomes, while relatively little is known about how customers experience the interface itself. This paper presents a synthesis of results from a series of user research studies conducted with small- and medium-sized enterprises (SMEs) in Canada, the United States, and Australia. | Download | mtrp |
| The Iterative Design of a University Energy Dashboard | Angela Sanguinetti, Marco Pritoni, Kiernan Salmon, Joshua Morejohn | Conference Paper | ACEEE Summer Study on Energy Efficiency in Buildings | 2016 | Energy dashboards are monitoring and display systems that provide information about building energy use. Dashboards may provide information, alarms, and complex trends to support engineers in identifying energy inefficiencies in a building. Public interfaces may contain simpler trends, with a greater focus on aesthetics and framing of content to promote interest and engagement. | Download | mtrp |
| TherMOOstat: Occupant Feedback to Improve Comfort and Efficiency on a University Campus | Angela Sanguinetti, Marco Pritoni, Kiernan Salmon, Joshua Morejohn | Conference Paper | ACEEE Summer Study on Energy Efficiency in Buildings | 2016 | Despite the significant amount of energy spent on Heating, Ventilation, and Air Conditioning (HVAC) at universities, thermal comfort conditions in campus buildings are frequently poor. Conventional HVAC management systems at universities are typically out of the hands of building occupants and facilities management departments have limited resources to involve them. These factors can lead to over-heating or over-cooling and undiagnosed mechanical issues. | Download | mtrp |
| Impacts of Duct Leakage on central outdoor-air conditioning for commercial-building VAV systems | Sreenidhi Krishnamoorthy, Mark Modera | Academic Journal Paper | 2016 | The purpose of this study was to estimate the energy losses due to duct leakage during central heating and cooling of outdoor air in commercial buildings with VAV systems. This was accomplished by calculating the required cooling and pre-heating of outdoor air with and without duct leakage for hot, moderate and cold climates. Our simplified model uses hourly weather data, along with leakage level, outdoor air fraction,and fan flow profiles to estimate heating and cooling loads associated with conditioning outdoor air for a typical office building. | Download From Journal Website | wcec | |
| Design of Compact Heat Exchangers for Supercritical Carbondioxide Cycles | Erfan Rasouli, Samikshya Subedi, Vinod Narayanan, Anthony D. Rollett, Jack Beuth, Kevin Drost | Confrence Proceeding Paper | 2016 | Supercritical carbondioxide (sCO2) cycles are being proposed in recent years for power generation from a variety of heat sources including fossil, nuclear, solar and geothermal. Advantages of using sCO2 include smaller power block size, high efficiency at moderate temperatures, and potential simplicity in power plant controls. In an indirect cycle, the working fluid is contained within a high pressure closed loop; heat is added into the working fluid in a high temperature high pressure primary heat exchanger. Designs of compact primary heat exchanger in such cycles were discussed in this paper. The designs include considerations for maximizing heat transfer rate while reducing pressure drop, uniform flow distribution, mechanical integrity of the HX, and fabrication approaches. | Download From Journal Website | wcec | |
| Performance Assessment of a Wide Diameter Shallow Bore Ground Source Heat Exchanger | Jose Garcia, Jonathan Woolley, Theresa Pistochini | Project Report | 2016 | This study investigated the in-situ performance of a new ground heat exchanger technology installed as the source for a water-to-water heat pump in a single family residence. The technology is different from traditional ground heat exchangers because it is installed in a shallow wide diameter bore (20’ deep x 24” diameter). This design reduces the cost and complexity of drilling compared to deeper heat exchanger bores. Whereas traditional systems consist of a U-shaped pipe in a small diameter bore, the technology studied here consists of a single pipe wound into a 24” diameter helix – in this way, roughly 300’ of heat exchanger pipe are fit into each shallow bore. | Download PDF | wcec | |
| Do occupancy-responsive learning thermostats save energy? A field study in university residence halls | Marco Pritoni, Jonathan M. Woolley, Mark Modera | Academic Journal | 2016 | Occupant presence and behavior can and should influence energy use in buildings. If occupancy is measured, predicted, or otherwise inferred, building controls can automatically adjust system operating parameters to use less energy without sacrificing user services. However, previous field evaluations and simulation studies appear to have overestimated the energy savings associated with this type of smart control. In this article we present results from a carefully controlled field evaluation of occupancy-responsive learning thermostats installed in every bedroom of three high rise university residence halls. While a standard practice energy model developed prior to the retrofit estimated 10–25% savings for cooling and 20–50% savings for heating, measurements reveal that the control scheme only reduced energy consumption by 0–9% for cooling, and by 5–8% for heating for normal operation during academic periods. However, for non-academic periods when the residence halls were sparsely populated,the scheme reduced cooling energy consumption by 20–30%. We analyzed these observations in relation to occupancy patterns, room temperature records, ambient conditions, and equipment run time. The findings provide novel insight about how to improve field evaluations and refine model assumptions to better predict the impact of occupancy-responsive thermostat controls. Notably, while analysts often use fractional building occupancy trends to simulate building energy performance, this study highlights the importance of accounting accurately for both the temporal and spatial variation of vacancy events throughout a building. | Download From Journal Website | wcec | |
| Technical and economic feasibility of unitary, horizontal ground-loop geothermal heat pumps for space conditioning in selected california climate zones | Steven Wiryadinata, Mark Modera, Bryan Jenkins, Kurt Kornbluth | Academic Journal Paper | 2016 | This work investigates the viability of unitary 3.5 kWt, ground-source terminal heat pumps (GTHP) employing horizontally drilled geothermal heat exchangers (GHX) relative to air-source packaged terminal heat pumps (PTHP) in hotels and motels and residential apartment buildings in California’s coastal and inland climates. The GTHP can reduce hourly peak demand for the utility by 7–34% compared to PTHP, depending on the climate and building type. The annual energy savings of up to 5% are highly dependent on the water-pump energy consumption relative to savings associated with the ground-air temperature difference (T). In mild climates with small T, the pump energy use may overcome savings from utilizing a GHX. The levelized cost savings, ranging from $1.7/yr-m2 to $3.6/yr-m2, were mainly due to reduced maintenance and lifetime capital costs. Without these reductions, the GTHP does not appear to offer significant advantages over PTHP in the climates studied. The GTHP levelized cost was most sensitive to variation in installed cost and system efficiency. These results can inform installers and decision makers about the viability of this technology, which is highly dependent on climate and building type. | Download | wcec | |
| Concrete mixture proportioning for desired strength and reduced global warming potential | Sabbie A Miller, Paulo JM Monteiro, Claudia P Ostertag, Arpad Horvath | Peer-reviewed Article | Construction and Building Materials | 2016 | In this research, formulae for predicting compressive strength and global warming potential (GWP) per cubic meter of concrete are proposed. | Read Report | mdsc |
| Influence of carbon feedstock on potentially net beneficial environmental impacts of bio-based composites | Sabbie A Miller, Sarah L Billington, Michael D Lepech | Peer-reviewed Article | Journal of Cleaner Production | 2016 | Natural fiber composites are of increasing interest in research because of their potential to provide a low environmental impact material for applications, such as in the construction industry. In this analysis, fully bio-based composites with varying natural fiber reinforcement in a biosynthesized polymer matrix were assessed. | Read Report | mdsc |
| Readily implementable techniques can cut annual CO2 emissions from the production of concrete by over 20% | Sabbie A Miller, Arpad Horvath, Paulo JM Monteiro | Peer-reviewed Article | Environmental Research Letters | 2016 | Due to its prevalence in modern infrastructure, concrete is experiencing the most rapid increase in consumption among globally common structural materials; however, the production of concrete results in approximately 8.6% of all anthropogenic CO 2 emissions. | Read Report | mdsc |
| Comparison indices for design and proportioning of concrete mixtures taking environmental impacts into account | Sabbie A Miller, Paulo JM Monteiro, Claudia P Ostertag, Arpad Horvath | Peer-reviewed Article | Cement and Concrete Composites | 2016 | As awareness and concern for greenhouse gas emissions grow, methods for reducing a significant industrial emission source, the production of cement for use in concrete, have been appearing. Assessments of these methods typically do not take into account the influence of material properties and environmental impacts concurrently. | Read Report | mdsc |
| Fuel Consumption Impacts of Auto Roof Racks | Chen, Yuche, and Alan Meier | Peer-reviewed Article | Energy Policy | 2016 | The after-market roof rack is one of the most common components attached to a vehicle for carrying over-sized items, such as bicycles and skis. It is important to understand these racks' fuel consumption impacts on both individual vehicles and the national fleet because they are widely used. We estimate the national fuel consumption impacts of roof racks using a bottom-up approach. | Read Article | |
| Characterization and Potential of Home Energy Management (HEM) Technology | Beth Karlin; Rebecca Ford; Angela Sanguinetti; Cassandra Squiers; John Gannon; Mukund Rajukumar; Kat A. Donnelly | Project Report | 2015 | The Home Energy Management (HEM) market is rapidly expanding alongside substantial investments to improve energy efficiency and upgrade electricity infrastructure to a smart grid. These changes enable consumers to take greater control of their energy use, which can be enabled through the use of Home Energy Management Systems (HEMS). | Download | mtrp | |
| Diffusion of Feedback: Perceptions and Adoption of Devices in the Residential Market | Beth Karlin, Angela Sanguinetti, Nora Davis, Kristen Bendanna, Kristen Holdsworth, Jessie Baker, David Kirkby, Daniel Stokols | Peer-reviewed Article | Lecture Notes in Computer Science | 2015 | Providing households with energy feedback is widely promoted as a conservation strategy and its effectiveness has been established in field studies. However, such studies actively recruit participants and little is known about naturalistic consumers. Despite hundreds of products emerging, few have taken hold in the market. Diffusion of innovation is a theory of technology adoption that details both the general process by which innovation spreads as well as the individual process of technology adoption. | Read Article (paywall) | mtrp |
| What about Everyone Else? Thinking Beyond the Customer: Market Barriers to Adoption of Efficient HVAC Technologies | Outcault, S. | Presentation | Behavior, Energy, and Climate Change Conference | 2015 | Identifies market barriers impeding the adoption of emerging HVAC technologies in California, using a behavior economics model of behavior change. | Presentation Slides | mtrp |
| Market Barriers to Widespread Diffusion of Climate-Appropriate HVAC Retrofit Technologies | Outcault, S. Kutzleb, J., Wooley, J. and K. Heinemeier. | Project Report | 2015 | Examines the market barriers impeding the adoption of emerging HVAC technologies in California, using a behavior economics model of behavior change. | Read Report | mtrp | |
| Assessment of the hybrid solar technologies for air conditioning in the Sustainable City of Dubai | Rahman, M.; Ghaddar, N.; Ghali, K.; Outcault, S.; P. Stroeve | Project Report | 2015 | This paper examines the technical requirements for a renewables-powered air conditioning system for a building in The Sustainable City of Dubai. | Read Report | mtrp | |
| Can AC Use be Reduced? Field Experiments to Encourage Adoption of Alternative Cooling Strategies in Japan and the U.S. | Outcault, S. Heinemeier, K., Pritoni, M., Kutzleb, J. and Q. Wang. | Project Report | 2015 | This paper reports on a pair of randomized control trial to encourage the use of passive cooling techniques in Japan and the U.S. | Read Report | mtrp | |
| Dual-Evaporative Pre-Cooling Retrofit Field Results | WCC, Jonathan Woolley, Paul Fortunato | Case Study | 2015 | The product tested in this project takes advantage of indirect evaporative cooling to cool the ventilation air stream on a conventional rooftop unit, and uses direct evaporative cooling to cool air at the condenser inlet. This dual design reduces energy by reducing the temperature of incoming ventilation air and by lowering the condensing temperature. Since the dual evaporative pre-cooling technology incorporates with a conventional air conditioner, the combined system still maintains latent cooling capacity for applications where dehumidification is required. These dual processes work together to increase cooling capacity and to improve efficiency for the vapor compression system. The second effect is mainly caused by a lower heat sink temperature for the refrigeration cycle. Laboratory measurements for the dual evaporative pre-cooling technology installed on a similar rooftop air conditioner indicated 43% reduction in power draw at peak. | Download PDF | wcec | |
| Smart Power for the Smart Home | Nelson Dichter, G.P. Li, Mark Modera, Keyue Smedley, Jonathan Woolley, Linyi Xia | Project Report | 2015 | Typical American households have a dynamic power quality factor varying from 0.8 to 0.95 depending on the signature of loads and their use at the time. (Appliances such as HVAC, motors, and lighting generate reactive and harmonic power, which is typically about 20% of the power consumption.) While photovoltaic (PV) panels via inverter provides mostly real power to home loads, the reactive power consumed by the loads would need to come from the electric grid and thus lowering the energy efficiency of the total system. Surging demand on reactive power at peak hours further induces instability to the grid. In this study, three aspects of this challenges and solutions are investigated, active power filter (APF) design, load disaggregation system design, energy modeling and testing of the systems above. | Download PDF | wcec | |
| Field Evaluation of Daikin Rebel Advanced Heat Pump Rooftop Unit | Jonathan Woolley, Ben Homquist, Caton Mande | Project Report | 2015 | The HVAC industry, policy leaders, and market stakeholders are making a concerted effort to improve efficiency for HVAC. The Daikin Rebel represents an important step in this direction. The use of variable speed vapor compression systems will almost certainly become a mainstay in future HVAC standards. However, these solutions are currently new to the market; manufacturers and practitioners do not yet fully understand the proper approach to design, installation, control, and optimization; nor do most recognize the practical limitations and the extended implications of their application. This study develops a deeper understanding about this class of variable speed multistage rooftop units, and provides insight into the real benefits that can be expected from such technologies. | Download PDF | wcec | |
| Field Evaluation of an Evaporative Condenser Air Pre-Cooler Retrofit | Jonathan Woolley, Robert McMurry, Christian Young, David Grupp | Project Report | 2015 | This study set out to carefully measure the in-field performance improvements for one evaporative condenser air pre-cooler, applied to improve the cooling efficiency for a data center. A secondary objective was to observe and document the real world experiences with this technology, and to develop some understanding about the longevity and maintainability for the technology. | Download PDF | wcec | |
| Field Evaluation of an Indirect Evaporative Air Conditioner | Jonathan Woolley, Christian Young & Caton Mande | Project Report | 2015 | This study evaluates the performance of one product – the Climate Wizard indirect evaporative air conditioner. For this project, the system was installed as a retrofit for a small restaurant in Rocklin, California. The technology was setup to operate in parallel with three existing rooftop air conditioners, and to provide all ventilation for the space. | Download PDF | wcec | |
| Market Barriers to Widespread Diffusion of Climate-Appropriate HVAC Retrofit Technologies | Sarah Outcault, Jennifer Kutzleb, Jonathan Woolley, and Kristin Heinemeier | Project Report | 2015 | This study seeks to identify market barriers and other factors impeding adoption and promotion of downstream climate-appropriate HVAC retrofit technologies, as well as develop opportunities to increase adoption and promotion by addressing market barriers. | Download PDF | wcec | |
| Can A/C Use Be Reduced? | Sarah Outcault, Kristin Heinemeier, Marco Pritoni, Jennifer Kutzleb, Qiwei Wang | Project Report | 2015 | The behavioral research team at UC Davis’ Western Cooling Efficiency Center (WCEC) was asked by the Tokyo Gas Company Ltd. to establish an ongoing research exchange focusing on two zero-net energy communities: E-Sogo in Yokohama, Japan and West Village in Davis, CA. The research focused on the impact of behavioral strategies and interventions on energy consumption in these two different communities. Interventions were designed for each community to understand the impacts of behavior on energy usage. The results from these different interventions are were then compared and used to develop recommendations for Tokyo Gas and future research studies on behavior‘s impact on energy usage. | Download PDF | wcec | |
| Energy Efficiency and the misuse of programmable thermostats | Marco Pritoni, Alan K. Meier, Cecilia Aragon, Daniel Perry, Therese Peffer | Academic Journal | 2015 | Programmable thermostats are generally sold as energy-saving devices controlling heating and cooling systems, but can lead to energy waste when not operated as designed by the manufacturers. We utilized Amazon Mechanical Turk, an online crowdsourcing service, to investigate thermostat settings and behavior in households. We posted a survey and paid respondents to upload pictures of their thermostats to verify self-reported data. About 40% of programmable thermostat owners did not use programming features and 33% had programming features overridden. Respondents demonstrated numerous misconceptions about how thermostats control home energy use. Moreover, we found that 57% of households were occupied nearly all the time, limiting the potential energy savings. The study revealed flaws in selfreported data, when collected solely from traditional surveys, which raises concerns about the validity of current thermostat-related research using such data. | Download From Journal Website | wcec | |
| The Wholesale Market Value of Dispatchable Efficiency for Commercial Air Conditioning | Jonathan Woolley, Thomas Jawin | Research Paper | 2015 | We explore the demand response opportunity through dispatchable, efficient air conditioning technologies that reduce peak electricity demand from cooling by 40%. | Download PDF | wcec | |
| Climate Appropriate Cooling for a Grocery Store: Hybrid Unitary DOAS System in San Ramon, CA | Jonathan Woolley, Robert McMurry | Project Report | 2015 | The research reported herein directly supports California Energy Efficiency Strategic Plan goals to accelerate marketplace penetration of climate appropriate air conditioning technologies. The report presents results from a field assessment of a dedicated outdoor air supply (DOAS) air hander that uses both indirect evaporative cooling and vapor compression to cool ventilation air for commercial buildings. This hybrid system was installed for an existing food store in San Ramon, California in combination with a whole building systems controls revision, and a closed door medium temperature refrigerated case lineup. In the year since installation, the project has demonstrated 20% whole building peak demand reduction, and 20% annual energy savings. The research work was executed by the UC Davis Western Cooling Efficiency Center and the PG&E Emerging Technology Program in collaboration with the major grocery chain, and with technical support from the technology manufacturer, and the project engineering, installation, controls and commission teams. | Download PDF | wcec | |
| Hybrid Rooftop Air Conditioners For a Mall, Fairfield CA | Nelson Dichter, Jonathan Woolley, Caton Mande | Project Report | 2015 | An inordinate amount of energy is wasted each year as a result of the fact that packaged commercial air conditioners are designed as ‘one-size fits-all’ products that can function in any climate and are not designed to achieve maximum efficiency for a specific climate. Climate appropriate solutions recognize unique opportunities for efficiency that arise from the climatic patterns and characteristics in particular regions. In California, these solutions include technologies that use water evaporation strategically to achieve substantial gains in cooling efficiency. The research reported herein directly supports California Energy Efficiency Strategic Plan goals to accelerate marketplace penetration of climate appropriate air conditioning technologies. The report presents results from a field assessment of two Trane Voyager RTUs that have been retrofitted with an Integrated Comfort Dual-Cool. The Dual-Cool retrofit uses direct evaporative cooling to precool the condenser air and indirect evaporative cooling to cool the ventilation air. Two of these hybrid systems were installed on a mall in Fairfield, California. One of the units serves tenant spaces and the other serves the common areas in the mall. When compared to manufacturer data for a similar RTU the field data showed an improvement in peak capacity by as much as 48% and an improvement in average capacity by as much as 45%. The field data showed an improved overall efficiency in all modes of operation and a decrease in power consumption by as much as 19%. However, some modes of operation showed an increased power draw of as much as 10%. | Download PDF | wcec | |
| Laboratory Performance Results: Indirect Evaporative Air Conditioning & Condenser Pre-Cooling as Climate Appropriate Retrofits for Packaged Rooftop Units | Curtis Harrington, Jonathan Woolley, Robert Davis | Project Report | 2015 | This report records results of a detailed laboratory evaluation of an indirect evaporative cooler and coupled to a rooftop packaged air conditioner (RTU) that was retrofit with a condenser air pre-cooler. The scheme reduces air conditioner compressor energy use in two main ways: 1. By reducing condenser inlet temperature and improving efficiency for the vapor compression cycle 2. By providing a substantial portion of the building cooling needs with indirect evaporative cooling | Download PDF | wcec | |
| Evaporative Condenser Air Pre-Coolers | Mark Modera, Theresa Pistochini | Project Report | 2015 | In order to understand the energy benefits associated with evaporative pre-coolers, the American Society for Heating, Refrigeration and Air Conditioning Engineers (ASHRAE) formed a Standard Project Committee (SPC-212P) to develop a Method of Test for “Determining Energy Performance and Water-Use Efficiency of Add-On Evaporative Pre-Coolers for Unitary Air Conditioning Equipment”. This report describes laboratory testing of five evaporative condenser air pre-cooler products on a packaged roof top unit and provided feedback to the ASHRAE SPC-212P. | Download PDF | wcec | |
| Laboratory Testing of Variable Speed Compressor and Fan Controls for RTU Optimization | Theresa Pistochini, Robert McMurry | Project Report | 2015 | This report describes a laboratory evaluation to optimize the performance and efficiency of a packaged air-conditioning and heating roof top unit (RTU) with a variable speed electrically communicated motor (ECM) controlling the blower speed and a retrofitted variable speed drive controlling the compressor speed. This technology is being considered as a method to save energy associated with air conditioning at part load conditions. It also may have potential to reduce peak electricity demand in buildings with over-sized equipment or when combined with condenser-air evaporative pre-cooling technology. | Download PDF | wcec | |
| HVAC Field Evaluation at SDG&E's Energy Innovation Center | Caton Mande | Project Report | 2015 | During the timeframe of March 2013 – September 2014, WCEC performed the diagnostic measurements and recorded observations while on-site at the facility. Information regarding normal building maintenance, HVAC set up, building controls, and building settings were determined from conversations with both the building manager of the Energy Innovation Center (EIC) and the HVAC technician that services the building. | Download PDF | wcec | |
| Polymer Bead Laundry | Will Allen | Project Report | 2015 | The WCEC performed a year long field study that monitored the performance of the Xeros laundry machines in real world operations. The study was conducted at a local athletic club. The study found that the Xeros laundry machine reduces water consumption by roughly 60%. Additionally, it found that energy savings, primarily due to not needing hot water, were roughly 87% when measured on a source energy basis. Significant cost advantages were also found, especially when used for high volume laundry operations. | Download PDF | wcec | |
| Gas Engine Heat Pump Technology | Nelson Dichter | Project Report | 2015 | The gas engine driven heat pump (GEHP) is a relatively new (first produced in 1985) heat pump technology whose purpose is to increase energy efficiency in water and space heating/cooling. This report details the results of a modeling study that compared the relative performance of three different building HVAC systems. The systems compared were a conventional AC and natural gas furnace, an electric heat pump system, and a gas engine driven heat pump. Each system was modeled in all of the California climate zones. Results for site energy, source energy, peak electrical draw, and annual cost in a time-of-use pricing structure were reported. | Download PDF | wcec | |
| Sub Wet-Bulb Evaporative Chiller (Nexajoule) | Theresa Pistochini, Robert McMurry | Project Report | 2015 | Several unique designs exist that are considered sub wet-bulb evaporative chillers, and this report focuses on one such design. The SWEC utilizes a two stage evaporative cooling system to chill water below the web-bulb temperature of the outdoor air. The theoretical limit for the supply water temperature is the dew point of the outdoor air. | Download PDF | wcec | |
| Hybrid Rooftop Air Conditioners with Dual Evaporative Pre-Cooling Performance Evaluation | Jonathan Woolley, Caton Mande | Project Report | 2015 | The purpose of this project was to gather field data to demonstrate and understand the performance of a hybrid rooftop air conditioner that uses dual-evaporative pre-cooling, essentially an RTU that employs the technology used to define the Western Cooling Challenge. | Download PDF | wcec | |
| Performance Evaluation for Indirect Evaporative Cooling on Cellular Sites | Jonathan Woolley, Caton Mande | Project Report | 2015 | The objective of this study is to conduct field evaluations of Indirect Evaporative Coolers (IECs) in California Climate Zone 8. IECs were installed at two different cellular sites in the cities of Cudahy, CA and Placentia, CA during the summer of 2014. The evaluation studied real-world equipment operation and developed characterizations of the overall system performance and energy efficiency across a range of operating conditions. The study is designed to investigate performance characteristics that cannot be captured by steady-state laboratory testing. | Download PDF | wcec | |
| Laboratory Test of a Sub Wet-Bulb Evaporative Chiller (Tsinghua) | Theresa Pistochini, Robert McMurry | Project Report | 2015 | Several unique designs exist that are considered sub wet bulb evaporative chillers, and this report focuses on one such design. The SWEC cools an outdoor air stream using an indirect evaporative cooling process. Part of this cooled, dry, outdoor air is delivered to the building as ventilation air; the rest is exhausted as part of the evaporative cooling process, which also chills a water supply used to cool the building. | Download PDF | wcec | |
| Laboratory Performance Results: Indirect Evaporative Air Conditioning and Condenser Pre-Cooling As Climate-Appropriate Retrofits for Packaged Rooftop Units | Jonathan Woolley | Project Report | 2015 | This report documents and discusses results of a detailed laboratory evaluation of an indirect evaporative cooler (IEC) coupled to a rooftop packaged air conditioner (RTU) that was retrofit with a condenser air pre-cooler. | Download PDF | wcec | |
| Greenhouse gas emissions from concrete can be reduced by using mix proportions, geometric aspects, and age as design factors | Sabbie A Miller, Arpad Horvath, Paulo JM Monteiro, Claudia P Ostertag | Peer-reviewed Article | Environmental Research Letters | 2015 | With increased awareness of the emissions of greenhouse gases (GHGs) and the significant contribution from the cement industry, research efforts are being advanced to reduce the impacts associated with concrete production and consumption. | Read Report | mdsc |
| A Framework for Engineering Sustainable Composites Based on Time-Dependent Material Properties and Environmental Impact Assessments: An Application to Bio-Based Composite Design | Sabbie A Miller, Michael D Lepech, Sarah L Billington | Project Report | 2015 | Improved design measures for civil engineering materials are necessary to reduce the environmental impact of the built environment. Over the last century buildings have been one of the largest consumers of materials. Due to growing material demands in the construction industry associated with increased global population and economic demands, it is imperative that research on designing materials use sustainability metrics in conjunction with performance metrics. | Read Report | mdsc | |
| Integrating durability-based service-life predictions with environmental impact assessments of natural fiber–reinforced composite materials | Sabbie A Miller, Wil V Srubar III, Sarah L Billington, Michael D Lepech | Peer-reviewed Article | Resources, Conservation and Recycling | 2015 | As concern about resource conservation has grown, research efforts have increased to develop materials out of rapidly renewable constituents, to assess their life cycle environmental impacts, and to predict their service-life performance. | Read Report | mdsc |
| Static versus Time-Dependent Material Selection Charts and Application in Wood Flour Composites | Sabbie A Miller, Michael D Lepech, Sarah L Billington | Peer-reviewed Article | Journal of Biobased Materials and Bioenergy | 2015 | With growing concern about the sustainability of materials, research efforts have increased in advancing material selection and design methods to incorporate environmental impact metrics. However, these tools typically are based on initial properties, which are assumed to remain static during the duration of material use and do not account for time-dependent material properties. | Read Report | mdsc |
| Circumvention Through the Years | Meier, Alan | Other | European Council for an Energy Efficient Economy | 2015 | The outrage against VW is justified, but let's not forget that other manufacturers ‚a lot of manufacturers, have been circumventing energy and emissions tests for decades. Here are a few of my own experiences. | Read Article | |
| Efficient use of land to meet sustainable energy needs | Hernandez, Rebecca R; Hoffacker, Madison K; Field, Christopher B; | Project Report | Nature | 2015 | To identify areas meeting land, energy, and environmental (LEE) compatibility for small- and utility-scale solar energy (USSE) in the state of California, we developed the Carnegie Energy and Environmental Compatibility (CEEC) Model | Download Report | |
| Solar Energy development impacts on land cover change and protected areas | Hernandez, Rebecca R; Hoffacker, Madison K; Murphy-Mariscal, Michelle L; Wu, Grace C; Allen, Michael F; | Project Report | PNAS | 2015 | Decisions determining the use of land for energy are of exigent concern as land scarcity, the need for ecosystem services, and demands for energy generation have concomitantly increased globally. Utility- scale solar energy (USSE) [i.e. a 1 megawatt (MW)] development re- quires large quantities of space and land; however, studies quantifying the effect of USSE on land cover change and protected areas are limited. | Read Article | |
| Development of Test Protocol for Direct Evaporative Condenser Air Precoolers | Theresa E. Pistochini, Perry L. Young, Mark Modera | Academic Journal | 2014 | Evaporative precoolers for air-cooled condensing units have been demonstrated to reduce electricity demand and save energy, particularly in arid climates. However, no objective, standardized test data for these products exists in the United States, making it difficult for end-users and utilities to evaluate expected performance prior to purchase and installation. This paper proposes a test protocol for evaporative precoolers installed on condensing units up to 70 kW, and then executes the protocol using three precooling products designed for residential split system air conditioners. | Read the Article | wcec | |
| Recent Applications of Aerosol Sealing in Buildings | Curtis Harrington, Mark Modera | Academic Journal | 2014 | This paper describes two recent applications of aerosol sealing techniques in buildings for improving indoor air quality and reducing energy required for heating, cooling, and ventilation. | Download PDF | wcec | |
| Multifamily Ventilation Code Change Proposal: Final Report | John Markley, Curtis Harrington, Nelson Dichter | Project Report | 2014 | This final report proposes changes to the 2016 California Title 24 Building Energy Efficiency Standards regarding indoor air quality ventilation of multifamily buildings. In summary, we recommend (a) unifying all multifamily residential ventilation requirements by extending current requirements for new low-rise multifamily buildings to new high-rise multifamily buildings, and (b) for high-rise multifamily buildings that use central shaft ventilation systems, two new requirements that are necessary to ensure that these systems perform as energy efficiently as possible and do not under- or over-ventilate homes. | Download PDF | wcec | |
| Thermostats Can't Fix This: Case Studies on Advanced Thermostat Field Tests | Sarah Outcault, Claudia Barriga, Kristin Heinemeier, John Markley and Dan Berman | Case Study | 2014 | The technology for thermostats has changed significantly in the past decade. More advanced features such as programmability offer great potential for energy savings. But with this increased technical complexity has come a corresponding complexity in the user interface. Some manufacturers have attempted to deal with this by adopting a deployment model that transfers to the installing contractor responsibility for the initial setup and user instruction. | Download PDF | wcec | |
| Modeling Ventilation in Multifamily Buildings | John Markley, Curtis Harrington, Garth Torvestad | Research Paper | 2014 | Proper ventilation is an essential component of multifamily building design due to its effects on occupant health and comfort. Though the concept of providing fresh air is straightforward, multifamily buildings pose several unique challenges that require special consideration in order to avoid excessive ventilation and energy waste. Two issues in particular that must be addressed in multifamily buildings are minimizing the air that moves between tenant spaces and ensuring that each individual space receives the required ventilation. In an effort to address these topics the UC Davis Western Cooling Efficiency Center, as part of a Public Interest Energy Research project, evaluated potential improvements to mechanical ventilation of multifamily buildings. This paper outlines the results from energy models of several multifamily building configurations to improve airflow balancing and energy efficiency in high-rise multifamily buildings with central shaft exhaust ventilation. | Download PDF | wcec | |
| Improving Cost Effectiveness of Radiant Floor Cooling | Richard Bourne, Theresa Pistochini, Jonathan Woolley | Project Report | 2014 | Radiant floors can reduce annual cooling energy costs up to 70% in comparison with conventional forced air cooling systems. Savings result from reducing blower energy use, improving cooling efficiency, and facilitating non-compressor cooling sources. The technology was developed in partnership with Walmart. It is suitable for use by most major retailers, and in other “large area” slabs in new retail malls, offices, and schools. Prior to this project, a related system was developed with Walmart by the UC Davis Western Cooling Efficiency Center and Viega LLC. That system is now marketed by Viega as “Climate Mat.”Climate Mat is the first “large area” pre-fabricated tubing array designed for low-cost installation of radiant cooling arrays in large buildings. Climate-Mat systems can be installed for approximately $2/sq.ft.; the goal of this project was to value-engineer the design toward lowering the installed cost by 50%, to $1/sq.ft. | Download PDF | wcec | |
| Why Occupancy-responsive Adaptive Thermostats do not Always Save--and the Limits for When They Should | Jonathan Woolley, Marco Pritoni, Therese Peffer, Mark Modera | Research Paper | 2014 | So-called ‘smart thermostats’ are beginning to fill the gap left in efficiency programs after researchers and policy makers discovered that in practice, simple programmable thermostats do not guarantee energy savings. As a result, EPA ended EnergyStar certification of programmable thermostats in 2010. Many recent pilots for communicating thermostats, occupancy-responsive thermostats, and adaptive control schemes have shown significant annual HVAC savings on the order of 10-20%. However, the form and function for technologies in this space vary widely. | Download PDF | wcec | |
| Internet-Connected, Occupancy-Responsive, Adaptive Thermostats for University Residence Halls | Marco Pritoni, David Grupp, Jonathan Woolley, Karl Johnson | Project Report | 2014 | Many recent field evaluations for communicating and occupancy-responsive thermostats have shown significant annual HVAC savings on the order of 10-20%. However, the form and function for technologies in this space vary widely. Occupancy responsive thermostats adjust mechanical system operating parameters to reduce energy consumption when a conditioned space is vacant. Unlike occupancy controls for lighting, the value of occupancy control applied to heating and cooling depends on a range of dynamic factors that are difficult to measure and assess with precision. For instance, the efficiency of heating and cooling equipment changes with weather conditions and part- or full-load runtime capacity, while thermal loads depend on the aggressiveness of indoor temperature set-points, and their dynamic relationship to a variety of physical and environmental factors. | Download PDF | wcec | |
| Laboratory Performance Results: Munters EPX 5000 Hybrid DOAS | WCC, Jonathan Woolley | Project Report | 2014 | The primary goal for this project was to characterize energy efficiency of the Munters EPX 5000 in all modes of operation, in all possible configurations, and across a full range of operating conditions. Laboratory test results were carefully analyzed to consider the technical opportunities and challenges related to the equipment and to identify opportunities for additional improvements to the technology. These results provide the basis for recommendations about how utility efficiency programs, design engineers, and customers might proceed to apply this type of technology for management of indoor environmental quality in commercial buildings while simultaneously reducing energy consumption and peak demand. | Download PDF | wcec | |
| Title 24 Credit for efficient Evaporative Cooling | Spencer Dutton, Jonathan Woolley, Nelson Dichter | Project Report | 2014 | develop a new model for the EnergyPlus building energy simulation tool that can be used to simulate a new generation of high efficiency air conditioners that combine different cooling technologies in order to leverage the strengths of each. These “hybrid” cooling systems have the potential to use substantially less energy than conventional air conditioning systems. However, there are currently no modeling tools or methods to accurately project energy savings for these systems. Accordingly, there is not currently a suitable Title-24 compliance pathway for hybrid air conditioning systems. The development of this model should provide the basis to support simulations for Title 24, or for the evaluation of programs and efforts that support the California Energy Efficiency Strategic Plan goal to advance the market transfer of “climate appropriate” cooling strategies. | Download PDF | wcec | |
| Automated Duct Sealing Demonstration | Will Allen, Karl Johnson | Project Report | 2014 | This report details the sealing of the UC Davis Art building duct system using the Aeroseal process, and describes the savings that can be expected based on measurements of the pre-seal airflows and historic energy usage, combined with measurements of the degree of sealing achieved. Savings are predicted due to both reduced fan energy required to deliver air to the registers, and to the elimination of loss of conditioned air. | Download PDF | wcec | |
| Side-By-Side Evaluation of Two Indirect Evaporative Conditioners Added to Existing Packaged Rooftop Units | Jonathan Woolley, Caton Mande & Mark Modera | Western Cooling Challenge Project Report | 2014 | The overarching goal of this pilot demonstration project was to explore and document the field application of indirect evaporative cooling applied as a retrofit to existing commercial HVAC equipment. Climate appropriate cooling is a key goal within the California Energy Efficiency Strategic plan. | Download PDF | wcec | |
| Dualcool Hybrid Rooftop Unit Field Test | WCC | Western Cooling Challenge Case Study | 2014 | Hybrid air conditioners, like the variable speed multi-stage rooftop unit with dual-evaporative pre-cooling observed in this study, can significantly reduce overall cooling energy and reduce peak demand energy through a combination of climate appropriate technologies and efficient part-load operation. Previous laboratory testing for this technology demonstrated 43% peak demand savings compared to the stated performance for ASHRAE 90.1 compliant equipment operating in California’s hot-dry conditions. The measured performance qualified this technology for the Western Cooling Challenge - a multiple winner competition hosted by UC Davis that encourages HVAC manufactures to develop air conditioners that reduce peak demand by at least 40% (Woolley 2012). | Download PDF | wcec | |
| Field Evaluation for a Dual-Evaporative Pre-Cooling Retrofit | WCC, Mark Modera, Jonathan Woolley, and Zhijun Liu | Project Report | 2014 | The purpose of this project was to gather field data to demonstrate and understand the performance improvement associated with adding an evaporative pre‐cooler for condenser‐inlet‐air and ventilation‐air to conventional RTUs. The tested retrofit was expected to save energy two ways: a) by cooling the outdoor air being delivered to the RTU indoor coil, and thereby reducing how much cooling it needs to perform, and b) by reducing the air temperature seen by the RTU condenser coil, thereby decreasing refrigerant pressure and the work that needs to be done by the compressor. The key metrics used to characterize the performance of the retrofit include: a) sensible Coefficient of Performance (COP), b) sensible cooling capacity, and c) electric power draw, all as a function of outdoor weather conditions. In addition, the project was designed to measure the on‐site water consumption associated with achieving those performance improvements, as well as to calculate key intermediate parameters, such as the sensible cooling capacity delivered to the ventilation air, and the maximum observable wet‐bulb effectiveness of the pre‐cooling system. Wet‐bulb effectiveness is a measure the ability of the evaporative media to cool the air entering the condenser toward the wet‐bulb temperature of the outside air, and is the key parameter used to characterize the performance of evaporative coolers for condenser air in the laboratory. The measured sump‐water temperature represents the coolest temperature produced by the pre-cooler, and therefore the highest observable wet bulb effectiveness. | Download PDF | wcec | |
| Field Performance Evaluation of Trane Voyager with DualCool | WCC, Jonathan Woolley, Caton Mande, and Mark Modera | Project Report | 2014 | The approach chosen for this evaluation was a field test conducted on three identical packaged rooftop units (RTUs) installed in Ontario, California. Two of these RTUs serve interior office space and the third unit serves a kitchen of a restaurant and bakery. The measure was factory-installed on the RTUs before they were installed on the buildings in September 2012. Monitoring involved minute-by-minute data collection on the RTUs, fitted with the measure and later with the measure removed. The evaluation focused on these key performance parameters: sensible COP, sensible cooling capacity, and electric power draw. | Download PDF | wcec | |
| Cloudfridge: A Cloud-Based Control System for Commercial Refrigeration Systems | Marco Graziano, Marco Pritoni | Research Paper | 2014 | This paper presents a novel hardware and software architecture that allows advanced control algorithms for commercial refrigerators to be developed, tested and deployed inexpensively. The aim of this new control framework is to optimize energy consumption as a software task, utilizing the benefits of lower cost computational resources inherent to cloud computing, minimizing on net overall energy usage of the refrigeration system. A prototype of the proposed system has been developed and tested under a California Energy Commission grant. | Download PDF | wcec | |
| Directional-Bore Ground Source Heat Pump Field Report | David Grupp | Project Report | 2014 | The project at Rio Mondego was a demonstration of a ground source heat pump system utilizing directional boring technology. The construction of the heat exchanger utilized 5 directionally bored holes of approximately 130’ in length emanating from a single point manifold. Into these bores a conventional u-tube heat exchanger was placed and the bore was filled with grout. | Download PDF | wcec | |
| A Simplified CFD Model for Steady Transitional Flow in Narrow U-shaped Channels | Zhijun Liu, Jean-Jacques Chattot, Mark Modera | Conference Paper | 2014 | A simplified CFD model that facilitates rapid analysis of steady transitional flow in narrow U-shaped channels is proposed, formulated, and numerically implemented. A depth-averaging technique is used to reduce the original three-dimensional (3-D) Navier-Stokes (N-S) equations to two-dimensions (2-D) with a unique treatment of the viscous terms, which are expressed in terms of the local wall shear stress and computed through a use of the Colebrook correlation for transitional and turbulent flow in channels. | Download | wcec | |
| Incorporating spatiotemporal effects and moisture diffusivity into a multi-criteria materials selection methodology for wood–polymer composites | Wil V Srubar III, Sabbie A Miller, Michael D Lepech, Sarah L Billington | Peer-reviewed Article | Construction and Building Materials | 2014 | Naturally occurring biopolymers have demonstrated suitability for use in wood–polymer composites (WPCs), which have the potential to replace petroleum-based plastics, wood, and engineered-wood materials in construction applications. However, widespread applicability of WPCs remains limited because of long-term durability concerns, especially in high-humidity and wet environments. | Read Report | mdsc |
| Renewable biobased composites for civil engineering applications | SL Billington, WV Srubar, AT Miche, SA Miller | Peer-reviewed Article | Sustainable Composites: Fibers, Resins and Applications | 2014 | While today’s built environment is a woven urban fabric of as-sembled civil engineered systems including transportation, public works, wastewater, and hydroelectric facilities, the construction and operation of buildings is one of the greatest consumers of all materials, energy, and natural resources worldwide. | Read Report | mdsc |
| Environmental impacts of utility-scale solar energy | Hernandez, RR; Easter, SB; Murphy-Mariscal, ML; Maestre, FT; Tavassoli, M; Allen, EB; Barrows, CW; Belnap, J; Ochoa-Hueso, Ravi; Ravi, S; | Peer-reviewed Article | Renewable and Sustainable Energy Reviews | 2014 | Renewable energy is a promising alternative to fossil fuel-based energy, but its development can require a complex set of environmental tradeoffs. A recent increase in solar energy systems, especially large, centralized installations, underscores the urgency of understanding their environmental interactions. Synthesizing literature across numerous disciplines, we review direct and indirect environmental impacts – both beneficial and adverse – of utility-scale solar energy (USSE) development, including impacts on biodiversity, land-use and land-cover change, soils, water resources, and human health. Additionally, we review feedbacks between USSE infrastructure and land-atmosphere interactions and the potential for USSE systems to mitigate climate change. Several characteristics and development strategies of USSE systems have low environmental impacts relative to other energy systems, including other renewables. We show opportunities to increase USSE environmental co-benefits, the permitting and regulatory constraints and opportunities of USSE, and highlight future research directions to better understand the nexus between USSE and the environment. Increasing the environmental compatibility of USSE systems will maximize the efficacy of this key renewable energy source in mitigating climatic and global environmental change. | Read Article | |
| Land-use efficiency of big solar | Hernandez, Rebecca R; Hoffacker, Madison K; Field, Christopher B; | Peer-reviewed Article | Environmental Science & Technology | 2014 | "As utility-scale solar energy (USSE) systems increase in size and numbers globally, there is a growing interest in understanding environmental interactions between solar energy development and land-use decisions. Maximizing the efficient use of land for USSE is one of the major challenges in realizing the full potential of solar energy; however, the land-use efficiency (LUE; Wm–2) of USSE remains ambiguous. We quantified the capacity-based LUE of 183 USSE installations (>20 MW; planned, under construction, and operating) using California as a case study. size and numbers globally, there is a growing interest in understanding environmental interactions between solar energy development and land- use decisions. Maximizing the efficient use of land for USSE is one of the major challenges in realizing the full potential of solar energy; however, the land-use efficiency (LUE; Wm−2) of USSE remains ambiguous. We quantified the capacity-based LUE of 183 USSE installations (>20 MW; planned, under construction, and operating) using California as a case study. " | Read Paper | |
| Advanced Diagnostics & Service for Rooftop Air Conditioners | Jonathan Woolley | Case Study | 2013 | AirCare Plus® is a third-party energy efficiency program that provides contractors with the necessary training, tools, and incentives to conduct quality in-field assessment of efficiency for commercial rooftop air conditioners. Service provided through the program is different from that of typical maintenance contractors especially in that evaluation of equipment performance is conducted using the Service Assistant™ developed by Field Diagnostics. This field tool is a hand held data acquisition device that measures pressure, temperature, and humidity at ten key points in an air conditioner and automates thermodynamic diagnosis of the vapor compression cycle. | Download PDF | wcec | |
| Facilitating Energy Savings with Programmable Thermostats: Evaluation and Guidelines for the Thermostat User Interface | Marco Pritoni, Therese Peffer, Daniel Perry, Cecilia Aragon, Alan Meier | Academic Journal Paper | 2013 | After conducting a usability study of programmable thermostats, we reviewed several guidelines from ergonomics, general device usability, computer-human interfaces, and building control sources. We analyzed the characteristics of thermostats that enabled or hindered successfully completing tasks and in a timely manner. Subjects had higher success rates with thermostat displays with positive examples of guidelines, such as visibility of possible actions, consistency and standards, and feedback. We suggested other guidelines that seemed missing, such as navigation cues, clear hierarchy, and simple decision paths. | Download From Journal Website | wcec | |
| Demand Control Kitchen Ventilation | David Grupp | Case Study | 2013 | This study is a summarized compilation of select SPEED case studies to demonstrate the efficacy of demand control kitchen ventilation in different environments ranging from 7 to 40 horsepower. Installations have been performed for combined hood and make-up air motor nameplate ratings up to 90 horsepower. | Download PDF | wcec | |
| Demand Control Kitchen Ventilation BUSINESS CASE | David Grupp | Business Case Study | 2013 | This business case provides 3 different scenarios for estimated savings, incentives and on bill financing information for Demand Control Kitchen ventilation. Title 24 changes take effect January 1, 2014 and will significantly alter the baseline for calculating incentives. | Download PDF | wcec | |
| Swimming pools as heat sinks for air conditioners: California feasibility analysis | Curtis Harrington, Mark Modera | Academic Journal Paper | 2013 | Earlier studies used field testing of swimming pool temperatures to validate a mathematical model for predicting the temperature of an unheated pool. Combining those results with manufacturers’ data on the performance of vapor-compression air conditioners as a function of heat rejection temperature, the analyses in the paper suggest that rejecting air conditioning heat to a swimming pool can save approximately 25–30% of single-family residential cooling electricity use and reduce cooling electricity demand during peak conditions by 30–35%, as compared to using the same compressor to reject the heat to ambient air. | Download From Journal Website | wcec | |
| Condenser Air Pre-Cooler Retrofits | Jonathan Woolley, David Grupp | Case Study | 2013 | Evaporative pre-coolers are effective retrofits to reduce the temperature of air that cools the condenser coil in air-cooled chillers, RTUs and other DX equipment. In these systems, the outside air stream passes over a wetted surface before it reaches the condenser, heat from the outside air is absorbed by water evaporation thus cooling the air stream. Evaporative condenser pre-coolers are applicable to most all climate zones, but have even more energy impact in lower humidity areas, such as California. | Download PDF | wcec | |
| Condenser Air Pre-Cooler Retrofits For Rooftop Units | Jonathan Woolley, David Grupp | Project Report | 2013 | A CSGS and BAFB working team was established to recommend and install PIER solutions at the Contrails Inn Dining Facility as the first step to show how these technologies might be successfully implemented at other Air Force bases and facilities. As part of this task, the team evaluated base energy loads, occupant usage patterns and facility operation schedules. Based on this data, the working team was able to present lighting and HVAC retrofit recommendations. This document summarizes the evaporative condenser air pre-cooler retrofit on a 50-ton Trane® chiller portion of the demonstrations at the 15,000 square foot Contrails Dinning Facility. | Download PDF | wcec | |
| Multi-Tenant Light Commercial Preliminary Report | John Markley, Marco Pritoni | Project Report | 2013 | The UC Davis Multi-Tenant Light Commercial project intends to establish a building level retrofit package that will substantially improve energy performance by collectively improving the envelope, lighting and HVAC systems. The primary goals of the UC Davis Multi-Tenant Light Commercial project are to increase the overall energy efficiency and permanently reduce the peak energy consumption of MTLC buildings. Simultaneously, the Multi-Tenant Light Commercial project aims to make these packages more economically feasible by leveraging the economy of scale through maximizing purchase potential, and by minimizing the cost through reducing the required contractor visits necessary to perform the work. | Download PDF | wcec | |
| Coolerado H80 Field Report at China Lake, CA | WCC | Project Report | 2013 | Field test results for the Coolerado H80 hybrid indirect evaporative air conditioner at NAWS China Lake, California. | Download PDF | wcec | |
| Coolerado H80 Field Test at UC Davis | Jonathan Woolley, Paul Fortunato, David Grupp | Case Study | 2013 | Field test results for the Coolerado H80 hybrid indirect evaporative air conditioner at the University House, at UC Davis. | Download PDF | wcec | |
| Shut the Sash: Fume Hood Ventilation in Laboratories | David Grupp | Case Study | 2013 | One of the simplest ways to reduce the energy required by operating laboratory fume hoods is to ensure that the sash—the moveable pane in front of the fume hood that controls the exhaust flow from an experiment—is always in the lowest possible operating position. This simple action can in some circumstances lower the amount of energy used substantially and will in all cases provide for the safest working environment, even in cases where energy use is not reduced. Behavioral change programs to promote being mindful of sash heights have been dubbed “Shut-the-sash” (STS). WCEC observed the effect of such behavioral programs at two university campuses. | Download PDF | wcec | |
| RTU Efficiency Optimizers | David Grupp | Case Study | 2013 | Several new retrofit controllers are now available for single-zone rooftop-unit (RTU) air conditioners that take advantage of energy saving techniques not previously economically possible. These retrofits work by replacing the simplistic stock control unit with new digital controls, new sensors, and often upgrade the single speed supply fan motor to take advantage of variable frequency drive (VFD) motor controllers. WCEC observed the performance of the CATALYST RTU Optimizer system at two university campuses. | Download PDF | wcec | |
| Reducing Maintenance-Water Consumption in Evaporative Cooling Equipment | Mark Modera | ASHRAE Summer 2013 Presentation | 2013 | This presentation explains why calcium and magnesium behave differently in the production of scale in evaporative cooling equipment. With this knowledge, proper maintenance techniques that diminish scale production can actually reduce water consumption while increasing equipment longevity. | Download PDF | wcec | |
| Simplified Thermal Modeling of Indirect Evaporative Heat Exchangers | Zhijun Liu, William Allen, Mark Modera | Academic Journal | 2013 | A simplified model using a modified effectiveness–Number of Transfer Units (NTU) method for thermal performance simulation of indirect evaporative heat exchangers is presented and then validated utilizing experimental data from the literature. The objective of this model is to facilitate efficient computer simulation of indirect evaporative cooling or hybrid indirect evaporative cooling/direct expansion vapor compression systems, both of which include an indirect evaporative heat exchanger as a core component. Through some approximations, the governing differential equations that describe indirect evaporative heat exchanger heat/mass transfer behavior are modified to produce a methodology that is analogous to the effectiveness–NTU method for sensible-only heat exchangers. | Download | wcec | |
| An investigation of coupling evaporative cooling and decentralized graywater treatment in the residential sector | Erica McKenzie, Theresa Pistochini, Frank Loge, Mark Modera | Academic Journal Paper | 2013 | Total electricity and water burdens, including both direct and indirect uses, were modeled for newly constructed and 15-year-old homes in six California climate zones for three air conditioning systems: standard air-cooled condensing unit, evaporatively pre-cooled condensing unit, and an evaporative condensing unit. Compared to the air-cooled condensing unit, average annual direct electricity savings were 17.7% and 11.3% for an evaporatively pre-cooled condensing unit and an evaporative condensing unit, respectively. The evaporative condensing unit provided greater savings at peak load than the evaporatively pre-cooled condensing units (peak power savings were 30.9% and 23.8%, respectively), which is promising for hot arid climates. | Download | wcec | |
| Low Pressure Air-Handling System Leakage in Large Commercial Buildings: Diagnosis, Prevalence, and Energy Impacts | Mark Modera, Craig Wray, Darryl Dickerhoff | Academic Journal Paper | 2013 | Air-handling system leakage reduces the amount of air delivered to conditioned spaces and in most cases wastes energy and money. Standards exist for where and how to measure system airtightness, but they tend to focus on new construction, and only on the high-pressure (1500 Pa to 2500 Pa (6 to 10 in. w.c.))/ medium-pressure (500 to 1500 Pa (2 to 6 in. w.c.)) portions of the system. This paper investigates air leakage in the “low-pressure” (≤500 Pa (≤2 in. w.c.)) portions of large commercial-building air-handling systems (i.e., downstream of variable-air-volume box inlet dampers). | Download | wcec | |
| Application of multi-criteria material selection techniques to constituent refinement in biobased composites | Sabbie A Miller, Michael D Lepech, Sarah L Billington | Peer-reviewed Article | Materials & Design (1980-2015) | 2013 | Biobased composites offer a potentially low environmental impact material option for the construction industries. Designing these materials to meet both performance requirements for an application and minimize environmental impacts requires the ability to refine composite constituents based on environmental impact and mechanical properties. | Read Report | mdsc |
| Evaluation of Functional Units Including Time-Dependent Properties for Environmental Impact Modeling of Biobased Composites | SA Miller, MD Lepech, SL Billington | Peer-reviewed Article | Journal of Biobased Materials and Bioenergy | 2013 | As understanding of anthropogenic effects on the environment grows, interest in developing more sustainable materials, such as biobased composites, is increasing. It is commonly assumed that biobased composites have fewer environmental impacts than petroleum based materials. | Read Report | mdsc |
| Improvement in environmental performance of poly(β-hydroxybutyrate)-co-(β-hydroxyvalerate) composites through process modifications | SA Miller, SL Billington, MD Lepech | Peer-reviewed Article | Journal of Cleaner Production | 2013 | As interest grows in developing materials with low environmental impact, research on bio-based composites is gaining attention in the composites industry. Bio-based composites are polymer matrix composites reinforced with natural fibers. | Read Report | mdsc |
| Mechanical and Environmental Characterization of Biobased Composites | SA Miller, MD Lepech, SL Billington | Project Report | 2013 | Interest in natural fiber reinforced composites has been growing because of their potential to offer low environmental impact alternative to conventional materials. Several studies have shown desirable mechanical properties can be achieved with polymer composites reinforced with natural fibers, but environmental impact is not typically meticulously quantified. | Read Report | mdsc | |
| The Complexities of Saving Energy in Qatar | Meier, Alan, Sinan Sabeeh, and Darwish Mohamed | Peer-reviewed Article | European Council for an Energy Efficient Economy | 2013 | Qatar presents unusual energy conservation challenges, some of which will appear elsewhere as the effects of climate change and environmental degradation increase. Qatar is endowed with huge reserves of natural gas but no fresh water. All of the fresh water is obtained through energy-intensive desalination processes—which may be responsible for as much as 40% of total gas use--resulting in many links between the supply and consumption of energy and water. Conserving water translates directly into saving energy. About 80% of the electricity in Qatari buildings is used to provide air conditioning; this is the highest fraction in any country in the world. The high rate of infrastructure construction temporarily distorts energy consumption patterns. | Read Article | |
| Laboratory Testing of Aerosol for Enclosure Air Sealing | Curtis Harrington, Mark Modera | Research Report | 2012 | Space conditioning energy use can be significantly reduced by addressing uncontrolled infiltration and exfiltration through the envelope of a building. A process for improving the airtightness of a building envelope by sealing shell leaks with an aerosol sealing technology is presented. | Download PDF | wcec | |
| Automated Fault Detection & Diagnostics for Rooftop Packaged Air Conditioners | Kristin Heinemeier | Case Study | 2012 | Automated Fault Detection & Diagnostics (AFDD) for RTUs is a technology class that senses key system operating parameters, detects performance degradation, and triggers an alarm that is communicated to some form of fault management tool, the zone thermostat, or appropriate facility personnel. California’s Energy Efficiency Strategic Plan urges the broader application of this technology, and Title 24 requires AFDD as a mandatory measure for all new commercial RTUs. | Download PDF | wcec | |
| Aerosol Duct Sealing in Central Exhaust Systems | Jonathan Woolley | Case Study | 2012 | Aeroseal is a cost effective method to seal leaks in ducts; it uses a vinyl polymer adhesive sprayed into the duct as an aerosol. Developed at Lawrence Berkeley National Laboratory, Aeroseal is designed to quickly repair leaks that are otherwise inaccessible without significant building renovation. | Download PDF | wcec | |
| Uncertainties in Achieving Energy Savings from HVAC Maintenance Measures in the Field | Kristin Heinemeier, Marshall Hunt, Marc Hoeschele, Elizabeth Weitzel, Brett Close | Research Paper | 2012 | HVAC maintenance measures have been demonstrated in the laboratory to have the potential to save a significant amount of energy. For example, Mowris et al. 2012 shows that by combining charge adjustment, airflow improvement, duct sealing, and elimination of non-condensables, over 30% of HVAC energy use can be saved. | Download PDF | wcec | |
| Trane Voyager DC Laboratory Results | WCC | Project Report | 2012 | Trane’s Voyager DC shows a savings of 43%. The explicit goal of the effort reported here was to laboratory test the Trane Voyager DC according to Western Cooling Challenge test protocol. The protocol evaluates equipment performance in hot-dry climate conditions, operating under realistic airflow resistances and with an outside air ventilation rate that would be encountered in typical commercial retail applications. A secondary goal was to laboratory test the equipment across a broad range of operating conditions in order to characterize performance in various scenarios, and to evaluate function of each major system sub-component and operating mode. | Download PDF | wcec | |
| Market Transformation Partnerships for Crossing the “Valley of Death” | Karl Johnson, David Weightman, Chris Scruton, Pedram Arani, Jonathan Woolley | Project Report | 2012 | Between the lab and the marketplace, new energy-efficient technologies often succumb to the "valley of death," a set of perilous barriers to market introduction that can prevent best practice technologies (with typical energy savings of 50% to 80%) from entering and transforming the market. The California Energy Commission created the State Partnership for Energy Efficient Demonstrations (SPEED) Program in 2004 to transform the market for deep energy-efficient products developed or enhanced with Public Interest Energy Research (PIER) Program funding. | Download PDF | wcec | |
| New Building Efficiency Evaluation at UC Davis | David Grupp, Paul Fortunato, Karl Johnson | Project Report | 2012 | Gallagher Hall and Conference Center is an 86,000 square-foot building at the University of California Davis. The building, opened in 2009 houses the Graduate School of Management and contains a mixture of classrooms, office space and conferencing facilities. The building is located outside of the central campus and does not have access to the campus district heating and cooling systems. This presented a challenge to the designers – but also an opportunity to think creatively and design a building for high efficiency from the ground up. The result was a building design that achieved LEED Platinum recognition. Many systems and design features made this possible, but most can be grouped into three main categories – the radiant heating and cooling system, the dedicated outside air system, and the solar management features. | Download PDF | wcec | |
| Condenser Air Evaporative Pre-Cooler Test Protocol | Theresa Pistochini, Mark Modera, Jay Madden | Project Report | 2012 | Systems are being introduced to the market that bring the advantages of this evaporative cooling process to small scale air-cooled AC systems. These systems are designed to be retrofitted onto existing units. They operate by evaporating water in the condenser air stream, cooling the incoming condenser air. While there are established test standards for rating the performance of air-cooled AC systems, a test standard to objectively compare the performance of condenser air evaporative pre-coolers doesn’t exist. The purpose of this study is to develop a test protocol for these systems, and to evaluate this protocol in a laboratory setting. | Download PDF | wcec | |
| Water Treatment and Management for Evaporatively Cooled Condensers | Theresa Pistochini, Curtis Harrington, Mark Modera, Erica R. McKenzie | Project Report | 2012 | The primary goal of this investigation was to provide long term laboratory test data to assess the longevity of an evaporatively-cooled condensing unit (ECCU) and to provide recommendations for operation and maintenance of the system to maintain performance and energy efficiency. A secondary objective was to evaluate water management strategies to minimize the use of bleed water and reduce the water consumption of the system. | Download PDF | wcec | |
| Water-Use Efficiency for Alternative Cooling Technologies in Arid Climates | Theresa Pistochini, Mark Modera | Academic Journal Paper | 2011 | Evaporative cooling technologies are generally valued for their reduced energy consumption in comparison to compressor-based air conditioning systems. However, two concerns that are often raised with respect to evaporative cooling equipment are their on-site water use and the impact of poor water quality on their performance. | Download From Journal Website | wcec | |
| Making Energy Savings Easier: Usability Metrics for Thermostats | Marco Pritoni, Daniel Perry, Cecilia Aragon, Alan Meier, Therese Peffer | Academic Journal Paper | 2011 | U.S. residential thermostats control approximately 9% of the nation’s energy use. Many building codes now require programmable thermostats (PTs) because of their assumed energy savings. However, several recent field studies have shown no significant savings or even higher energy use in households using PTs compared to those using non-PTs. These studies point to usability problems that lead to incorrect use and wasted energy. | Download From Journal Website | wcec | |
| Swimming pools as heat sinks for air conditioners: Model design and experimental validation for natural thermal behavior of the pool | Curtis Harrington, Mark Modera, Jonathan Woolley | Academic Journal Paper | 2011 | Swimming pools as thermal sinks for air conditioners could save approximately 40% on peak cooling power and 30% of overall cooling energy, compared to standard residential air conditioning. Heat dissipation from pools in semi-arid climates with large diurnal temperature shifts is such that pool heating and space cooling may occur concurrently; in which case heat rejected from cooling equipment could directly displace pool heating energy, while also improving space cooling efficiency. | Download From Journal Website | wcec | |
| Speakman Hybrid Rooftop Unit Performance: Western Cooling Challenge Laboratory Test Results | WCC, Jonathan Woolley | Project Report | 2011 | This report documents the results of Western Cooling Challenge laboratory tests of the Speakman Hybrid, a rooftop air conditioner that uses indirect evaporative cooling, direct evaporative cooling, and conventional vapor compression cooling. The Western Cooling Efficiency Center (WCEC) orchestrated the laboratory tests, which were conducted by the National Renewable Energy Laboratory under a commitment from the US Department of Energy Office of Building Technology to provide laboratory testing for advanced cooling technologies submitted to the Western Cooling Challenge. | Download PDF | wcec | |
| Western Cooling Challenge Test Protocol Development | WCC, Jonathan Woolley, Mark Modera | Research Paper | 2011 | This paper outlines and discusses the development of the test protocol and performance criteria for the Challenge. The choice of laboratory test conditions is discussed. The rationale for and calculation of performance metrics including nominal cooling capacity and credited cooling capacity are presented. Additionally, the assumptions underlying requirements for minimum sensible energy efficiency are summarized, and key non-performance-based criteria for the program are explained. | Download PDF | wcec | |
| Advancing Development of Hybrid Rooftop Packaged Air Conditioners: Test Protocol and Performance Criteria for the Western Cooling Challenge | Jonathan Woolley, Mark Modera | ASHRAE Journal | 2011 | This paper outlines and discusses the development of the test protocol and performance criteria for the Western Cooling Challenge. The choice of laboratory test conditions is discussed. The rationale for and calculation of performance metrics including nominal cooling capacity and credited cooling capacity are presented. Additionally, the assumptions underlying requirements for minimum sensible energy efficiency are summarized, and key nonperformance-based criteria for the program are explained. | Download | wcec | |
| Cars Are Buildings: Building-like Energy Use in Automobiles | Thomas, Valerie M.; Alan K. Meier; Siva G. Gunda; and Thomas P. Wenzel | Peer-reviewed Article | Transport and Environment | 2011 | This paper examines vehicle energy use as if vehicles were buildings. Vehicle air conditioners are much less efficient than residential air conditioners, and in the US consume about 0.9 quadrillion BTUs (quads) per year, comparable to the 2.3 by air conditioners in residences. Vehicle heating, in contrast, is a model of efficiency, running as a combined-heat-and-power system using waste heat from the motor. Electricity use from appliances such as DVD players, laptops, and refrigerators remains modest, although stand-by power use is growing. Technology and policy approaches used for buildings can address similar types of energy use in cars. | Read Article | |
| Central Hotel Guest Room Energy Controls | Theresa Pistochini, Curtis Harrington, Mark Modera | Project Report | 2010 | During the summer of 2010, occupancy controls and an energy management system (EMS) were installed at the Best Western Island Palms hotel in San Diego, CA. The study included 12 rooms that were instrumented with temperature and current loggers collecting data every 15 minutes. Four rooms were used as a base case with the occupancy and EMS controls turned off while the other eight rooms utilized the controls. The data was analyzed between three groups: Baseline, occupancy controls, and occupancy with EMS controls. | Download PDF | wcec | |
| Energy and Demand Savings from Sealing Exhaust | Jonathan Woolley, Joshua Gottlieb, Theresa Pistochini, Mark Modera | Project Report | 2009 | The goal of this project was to help the state of California address the energy losses associated with leakage in exhaust ductwork in commercial buildings and dormitory style residences. The study coupled computer modeling of zone pressures and flows as impacted by transient meteorological conditions with field research to answer a number of questions about the potential for energy savings from sealing leaks or reducing flows in exhaust ducts. Computer simulations were conducted in a multizone airflow modeling package and used to characterize the relationship between outdoor air infiltration and changes in exhaust flow. | Download PDF | wcec | |
| City Carbon Budgets: Aligning Incentives for Climate-Friendly Communities | Salon, Deborah; Daniel Sperling; Alan Meier; Sinnott Murphy; Roger Gorham; and James Barrett | Project Report | 2008 | Local governments can have a large effect on carbon emissions through land use zoning, building codes, transport infrastructure investments, and support for transportation alternatives. Recognizing this, many cities have developed climate action plans, containing a disparate mix of mostly voluntary greenhouse gas emissions reduction proposals. This paper describes an integrated climate policy instrument for local governments: city carbon budgets. We identify and evaluate options for creating an effective and acceptable institutional structure, allocating emission targets to localities, measuring emissions, providing flexibility and incentives to local governments, and assuring compliance. We also discuss the likely costs of such a policy. Our recommended policy structure is based on the principles of effectiveness, equity, efficiency, administrative ease, and political acceptability. | Read Article | ||
| Can You Take the Heat? A Cross-National Comparison of Thermal Comfort Strategies and Energy-Saving Field Experiments | Sarah Outcault, Marco Pritoni, Kristin Heinemeier, Ayako Mikami | White Paper | This paper presents a cross-cultural comparison of cooling strategies in sustainable communities in the United States and Japan to deepen our understanding of occupant behavior within the broader social context. We describe the “social potential” for energy conservation that could be tapped if alternatives to A/C were viewed through that lens. The paper draws on the lessons learned from a pair of interventions to encourage passive cooling strategies and reduce A/C use in an American community of zero energy buildings and a Japanese “smart home” community. | Download PDF | wcec | ||
| How People Actually use Thermostats | Marco Pritoni, Alan Meier, Cecilia Aragon, Becky Hurwitz, Dhawal Mujumdar, Therese Peffer, Daniel Perry | Research Paper | Residential thermostats have been a key element in controlling heating and cooling systems for over sixty years. However, today’s modern programmable thermostats (PTs) are complicated and difficult for users to understand, leading to errors in operation and wasted energy. Four separate tests of usability were conducted in preparation for a larger study. These tests included personal interviews, an on-line survey, photographing actual thermostat settings, and measurements of ability to accomplish four tasks related to effective use of a PT. | Download PDF | wcec | ||
| Usability of Residential Thermostats: Preliminary Investigations | Marco Pritoni, Therese Peffer, Daniel Perry, Cecilia Aragon, Alan Meier | Academic Journal Paper | Personal interviews revealed widespread misunderstanding of thermostat operation. The on-line surveys found that most thermostats were selected by previous residents, landlords, or other agents. The majority of occupants operated thermostats manually, rather than relying on their programmable features and almost 90% of respondents reported that they rarely or never adjusted the thermostat to set a weekend or weekday program. Photographs of thermostats were collected in one on-line survey, which revealed that about 20% of the thermostats displayed the wrong time and that about 50% of the respondents set their programmable thermostats on “long term hold” (or its equivalent). | Download From Journal Website | wcec | ||
| Home Energy Management: Products & Trends | Marco Pritoni, Janelle LaMarche, Katherine Cheney, Kurt Roth, Olga Sachs | Research Paper | Home Energy Management (HEM) describes a class of technologies including sensors, smart thermostats, and feedback devices seeking to manage residential energy consumption profiles to reduce peak electric demand and consumers’ electric bills. | Download PDF | wcec | ||
| Folk Labeling: Insights on Improving Usability and Saving Energy Gleaned from After-Market Graffiti on Common Appliances | Marco Pritoni, Therese Peffer, Jessica Granderson, Gari Kloss, Alan Meier, Cecilia Aragon | Research Paper | The after-market labeling of a device by its users often indicates problematic usability, which can affect the device's energy consumption. For example, when people find a lighting control panel difficult to use, they often write instructions on a piece of paper and affix it nearby as a reminder to themselves and to help others. | Download PDF | wcec | ||
| Principal Agent Problems in Energy Efficient Computing in a University Setting | Marco Pritoni, Siva Gunda, Tracy Hsieh | Research Paper | About 10% of the energy usage on a typical university campus is spent to meet Information Technology (IT) demands such as powering desktops, severs, printers, laptops, and other peripheral equipment. At UC Davis, the annual energy expenditure on IT alone was approximately $3 million (~$1.3 million excluding servers and related usage) in 2008. | Download PDF | wcec | ||
| How People Use Thermostats in Homes: A Review | Marco Pritoni, Therese Peffer, Alan Meier, Cecilia Aragon, Daniel Perry | Academic Journal Paper | Residential thermostats control a substantial portion of both fuel and electrical energyd9% of the total energy consumption in the U.S. Consumers install programmable thermostats to save energy, yet numerous recent studies found that homes with programmable thermostats can use more energy than those controlled manually depending on how or if they are used. At the same time, thermostats are undergoing a dramatic increase in capability and features, including control of ventilation, responding to electricity price signals, and interacting with a home area network. These issues warrant a review of the current state of thermostats, evaluating their effectiveness in providing thermal comfort and energy savings, and identifying areas for further improvement or research. | Download From Journal Website | wcec | ||
| Contractors Walk on the Wild Side... Why? | Kristin Heinemeier | Research Paper | It has been estimated that permits are obtained for fewer than 5% of air conditioner replacements in California homes. This means that 95% of jobs never comply with nor verify the energy efficiency measures of California’s energy code (not to mention the health and safety concerns with unpermitted work!). The Western HVAC Performance Alliance—an innovative Industry-Utility alliance comprised of contractors, manufacturers, distributors, unions, code officials, utility program managers, verification providers, and researchers—has posited that there are substantial behavioral elements to the problem. | Download PDF | wcec | ||
| Application for Entry to the Western Cooling Challenge | WCC | Western Cooling Challenge | Please submit a cover letter expressing your company’s intent to submit an entry to the Western Cooling Challenge. | WCC Application | wcec | ||
| Western Cooling Challenge Program Requirements | WCC | Western Cooling Challenge | The Western Cooling Challenge (WCC), hosted by the Western Cooling Efficiency Center (WCEC) at the University of California Davis, is a multiple winner competition that encourages HVAC manufactures to develop climate‐appropriate rooftop packaged air conditioning equipment that will reduce electrical demand and energy use in Western climates by at least 40% compared to DOE 2010 standards. | Download PDF | wcec | ||
| Occupancy Sensing Adaptive Thermostat Controls – A Market Review and Observations from Multiple Field Installations in University Residence Halls | Jonathan Woolley, Therese Peffer | Research Paper | While both occupancy sensors and the Internet have been around for many decades, recently both have been applied to programmable thermostats to reduce energy consumption and to improve usability and control. This paper explores the implications of coupling these technologies, and the role the added capabilities play on the efficiency and effectiveness of building conditioning. The research focuses on various installations of occupancy-sensing mesh-networked web-programmable thermostats in university residence halls, with a focus on the results from installation in multiple dormitories at the University of California, Davis. | Download PDF | wcec | ||
| One Machine for Heating Cooling & Domestic Hot Water: Multi-Function Heat Pumps to Enable Zero Net Energy Homes | Mark Modera, Jonathan Wolley, David Grupp, Bill Dakin, Michael Koenig | Research Paper | While traditional residential mechanical design uses multiple systems and fuels to provide thermal services, the emerging generation of heat-pump technologies can provide heating, cooling and domestic hot water with a single appliance. These heat pumps operate over a wider temperature range than their predecessors, offer substantial efficiency improvements, and introduce opportunities for waste heat recovery. | Download PDF | wcec | ||
| Open Software-Architecture for Building Monitoring and Control | Carl Blumstein, David Culler, Gabe Fierro, Therese Peffer, Marco Pritoni | Research Paper | Information technology can increase energy efficiency by improving the control of energy-using devices and systems. Awareness of this potential is not new—ideas for applications of information technology for energy efficiency have been promoted for more than 20 years. But much of the potential gain from the application of information technology has not yet been realized. Today a combination of new requirements for the operation of the electricity system and the development of new technology has the potential to cause a rapid increase in the pace of adoption of improved controls. In this paper we discuss one promising avenue for technology advancement. First, we review some basic concepts with emphasis on open software-architecture. Then we describe the components of XBOS, a realization of this open software-architecture. XBOS has the ability to monitor and control many different sensors and devices using both wired and wireless communication and a variety of communication protocols. Finally, we illustrate the capabilities of XBOS with examples from an XBOS installation in a small commercial office building in Berkeley California. | Download PDF | wcec | ||
| Method for Discovering Functional Relationships Between Air Handling Units and Variable-Air-Volume Boxes From Sensor Data | Marco Pritoni, Arka Bhattacharya, David Culler, Mark Modera | Research Paper | In Building Automation Systems contextual information about sensors is frequently missing or hard-coded in the control code. Retrieving this data is time consuming and error-prone, but necessary to write any type of control application. Automating metadata acquisition is a new and active area of research. Methods to infer metadata from sensor labels or from recorded data have been previously proposed. However, these methods are ineffective in uncovering the association between HVAC components. In fact, measured variables (pressures, temperatures, flows, valve positions) have slow and attenuated responses to changes in input variables, thus impairing the efficacy of correlation methods. In addition, sensor readings are frequently constrained between physical limits and kept around setpoints by nested control loops. For this reason, pure statistical methods fail to capture the differences between sensor streams and are unable to classify them. In this article, we propose a new method for discovering functional relationships between Air Handling Units and Variable-Air-Volume Boxes from sensor data. | Download PDF | wcec | ||
| Characteristic Performance Evaluation for Indirect Evaporative Cooling on Small Cellular Sites | Caton Mande, Jonathan Woolley, Mark Modera | Project Report | The objective of this study was to conduct field evaluations of the Indirect Evaporative Coolers (IECs) in California Climate Zone 8. The evaluation studied real world equipment operation at two different field sites and developed characterizations of the overall system performance and energy efficiency across a range of operating conditions. The study was designed to investigate performance characteristics that cannot be captured by steady state laboratory testing. For example, this evaluation carefully disaggregates performance in each mode of operation to consider the performance and efficiency of each system state, and to investigate the implications of the control strategies and field-selected settings that were applied. IECs were installed at two difference cellular sites in the cities of Cudahy, CA and Placentia, CA during the summer of 2014. | Download PDF | wcec | ||
| Energy-Efficiency Clothes Dryers: Self-Calibrating Automatic Cycle Termination Controller | Theresa Pistochini, Caton Mande | Project Report | This project developed an automatic dryer cycle termination controller that utilized the relationship between dryer drum inlet temperatures and outlet temperatures to accurately predict the end of the drying cycle. The technology promises to be more accurate and robust in performance under different load and environmental conditions in comparison to existing technology. | Download PDF | wcec | ||
| Modeling and Design Analysis of a Regenerative Indirect Evaporative Heat Exchanger Using an Effectiveness Method | Zhijun Liu, William Allen, Mark Modera | Academic Journal | Indirect evaporative cooling (IEC) is a water-based cooling technology that is attractive for space cooling in dry and hot climates due to its lower energy consumption (compared to vapor compression air conditioners) and lack of humidification (compared to direct evaporative cooling). The key component of advanced IEC or hybrid IEC/DX (Direct eXpansion vapor compression) systems(Elberling 2006) is the IEHX (indirect evaporative heat exchanger). A practical accurate model of an IEHX is needed to characterize the thermal behavior of these coolers and to support their implementation by HVAC designers. | Download | wcec | ||
| CAT on a Hot Tin Roof: Getting Climate Appropriate Technologies onto Rooftops in Hot Dry Climates | Jerine Ahmed, Edwin Hornquist, Mark Modera | Conference Paper | Approximately 65% of the commercial building sector is cooled by roof top units (RTUs) that are designed and optimized for nation-wide application. California has a long-standing commitment to meeting aggressive carbon reduction objectives. Can RTU performance be optimized for California’s unique climate? Would manufacturers be willing to produce solutions to meet these regional needs? To address these needs, the California investor-owned utilities and the Statewide Emerging Technologies program began a decade long effort to meet the challenge of getting climate appropriate RTUs onto California rooftops. This paper presents an accounting of the challenges along the way and the solutions that were employed to meet this goal, starting with the Western Cooling Challenge (WCC) to manufacturers, with efficiency targets based upon adding indirect evaporative cooling to direct expansion RTUs; >40% improvement in seasonal efficiency, and >50% improvement in peak efficiency relative to DOE 2010 minimum efficiency standard. The WCC incorporated lessons learned through research and demonstrations on RTU retrofits and has evolved towards innovative, less-costly solutions that add indirect evaporative cooling to existing RTUs. This paper presents the technical design of the WCC, laboratory and field test results for WCC technologies, laboratory and field test results for evaporative pre-coolers for RTUs. The paper also presents the development of an ASHRAE standard for testing RTU evaporative pre-coolers, including addressing value-chain acceptance issues, and water consumption concerns. The authors conclude with a discussion of the future of HVAC efficiency in California. | Download | wcec | ||
| Evaluation of the Next Generation Residential Space Conditioning System for California | Sara Beaini, Ammi Amarnath, Walter Hunt, Ronald Domitrovic, Sreenidhi Krishnamoorty, Curtis Harrington, Mark Modera, Robert Davis, Ryohei Hinokuma | Conference Paper | The ‘Next Generation’ Residential Space Conditioning System (Next-Gen RSCS) for California (CA) is an integration of multiple advanced HVAC technologies including: variable capacity heat pump compressor, variable speed blower fan, alternative refrigerant (R-32), automated demand response, fault detection and diagnostics, intelligent dual fuel heating (gas/electric), integrated ventilation, and zonal control. Along with the technology evaluation, an assessment was performed on duct losses for single versus multi-zone duct configurations with variable capacity equipment. The experimental results, from 3 leading laboratories, inform the industry on optimizing the system for efficiency, utility integration, and homeowner comfort. | Download | wcec |