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. The study accounted for long-run marginal emissions from electricity generation, emissions from natural gas combustion in homes, and fugitive methane and refrigerant emissions from leaks. The population weighted US average results show emission reductions for a heat pump over furnace to be 38–53% for carbon dioxide, 53–67% for 20-Year global warming potential (GWP), and 44–60% for 100-Year GWP, with reductions increasing over time. The impact of fugitive emissions from the furnace is significantly higher than that of the heat pump. While more energy efficient construction reduces overall emissions for both heating types, the forecasted percent emission reduction for replacement of a gas furnace with heat pump was not impacted by changes in home construction parameters.
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.
The California Air Resources Board (CARB) has approved a new regulation requiring refrigerants used in all new stationary residential air conditioning systems to have a 100-year GWP value of 750 or less. For reference, the most common refrigerant currently used in unitary air conditioning equipment is R-410A, which has a 100-year GWP of 2,088.
A number of refrigerant solutions have been developed to meet the CARB GWP requirement, but the majority of these refrigerants have a low level of flammability (A2L). While there are strategies for mitigating the risk of using flammable refrigerants, finding a non-flammable solution presents the easiest path to market and would not require additional safety controls and updates to codes and standards.
Thursday, December 16, 2021 | 2pm – 3:30pm PST
UC Davis’ Energy Graduate Group (EGG) is designed to meet the world’s growing need for highly qualified, thoughtful and dedicated leaders in sustainable energy systems. EGG offers MS and PhD degrees in Energy Systems in two tracks of study: Energy Science & Technology and Energy Policy & Management. Students take relevant coursework from across the UC Davis campus and conduct interdisciplinary research to address pressing environmental, economic, policy, and social challenges related to energy production and consumption facing California, the U.S., and the world.
In this Virtual Information Session you can:
- Learn more about the Energy Graduate Group
- Talk with students and faculty
- Discover what research faculty are conducting
- Find out about the application and admissions process
Scientists from the University of California-Davis, Lancaster University, and Ludong University in China published research showing that utility-scale solar facilities can have a cooling effect not only on the land covered by the array, but also in the surrounding area.
Solar facilities were found to produce “cool islands” that extend up to 700 meters from the boundaries of the arrays. Land surface temperature was reduced by up to 2.3 degrees Celsius (3.6 Fahrenheit) at 100 meters away; the cooling effects tapered off exponentially to 700 meters.
Studies of two solar parks–the 300 MW Stateline project in California and the 850 MW Longyangxia project in China–were conducted using Landsat satellite images, an approach the researchers said had not previously been applied to solar. The study team compared land surface temperatures around solar facilities before and after they were built. The Stateline solar park measurements were supplemented with ground-collected data.
The researchers hypothesized that the cooling was caused by a combination of shading and insulating the land surface, and by the direct conversion of energy into electricity by the solar panels.
Students at Rio Tierra Junior High School in Sacramento build a portable air cleaner using a box fan and high efficiency air filters.
Schools are facing many challenges this fall, including minimizing risks to students and staff from Covid-19 and wildfire smoke exposure. Air purifiers are one tool that can help.
Researchers from the UC Davis Energy and Efficiency Institute (EEI) partnered with science teachers at Rio Tierra Junior High School in Sacramento to teach a two-day lesson on air quality and build 30 portable air cleaners with approximately 150 8th grade students. The portable air cleaners will be distributed to every classroom on campus.
Knowledge to action
“It is really important to empower students and help them understand indoor and outdoor pollution sources, and how to measure and improve indoor air quality,” explained UC Davis researcher and project lead Theresa Pistochini. The lesson culminated with groups of 4-5 students constructing do-it-yourself (DIY) portable air cleaners using a Corsi-Rosenthal cube design, which uses a box fan and four filters with a MERV 13 rating. The materials for each air cleaner cost $75. Each air cleaner is expected to provide about the same amount of air cleaning effectiveness as small commercially available portable air cleaners that cost about $200.
Science teachers Amber Mitchell and Kathryn Graf planned the visit with UC Davis researchers Theresa Pistochini and Robert McMurry. “I love having outside speakers come in. Air quality is such a relevant topic that we are able to teach the kids about,” Mitchell said. “We are always trying to relate science to current events and student’s lives. There’s not much more relatable right now than making air purifiers to help our school.”
Students at Rio Tierra Junior High School in Sacramento investigate filter samples of various filtration efficiencies and discuss their observations with science teacher Amber Mitchell.
Importance of air quality
“Air quality is such an important topic that historically has not received much attention. I hope that our outreach to students will encourage them to think about the air they breathe, and consider engineering and environmental science as a career path,” Pistochini said. “While investments in permanent ventilation and filtration systems are the best way to improve indoor air quality long-term, portable air cleaners are a quick way to achieve some immediate benefits.”
Principal Adam Sinor supported the project and visited the classrooms to see the air cleaner construction in action. “With the wildfires and Covid, and the way Covid is spread through aerosols, it’s a way kids can take action to make their internal environment better and learn science and engineering at the same time,” Sinor said.
UC Davis researcher Theresa Pistochini working with students to build a portable air cleaner.
This project was funded by the UC Davis Sustainable Campus, Sustainable Cities initiative, which received funding from the Sacramento Municipal Utility District Sustainable Community Program. The initiative aims to engage K-12 students in energy-oriented STEM education, using experiential learning as well as citizen and community science to empower students to measure, analyze, understand, and manage their environment.
DIY Portable Air Cleaner Testing – https://energy.ucdavis.edu/wp-content/uploads/Case-Study_DIY-Portable-Air-Cleaners-083121.pdf
Photos – https://ucdavis.box.com/s/uwf09x39122r0b4pgdlwbgusaihjirnq
Website – https://wcec.ucdavis.edu/improving-indoor-air-quality-in-california-schools/
To solve some of the most pressing water and energy challenges, scientists and engineers need access to robust, reliable data that is often sensitive and protected. Data providers, researchers, and host institutions need to adhere to strict requirements for protecting and securing this data. The Center for Water-Energy Efficiency (CWEE) at the University of California, Davis (UC Davis) used Amazon Web Services (AWS) to create a centralized, secure data repository that streamlines data sharing.
Researchers at CWEE quantify how much energy is used in various elements of the water sector, including potable water, irrigation, and wastewater. This research helps water utilities, energy utilities, and policy makers decide how to invest in and promote water use efficiency, energy efficiency, and electric load shifting in the water sector. This research is critical particularly in California, where drought and other climate change outcomes, like heat waves and forest fires, have been an issue for decades and are growing more severe.
CWEE’s research heavily depends on large amounts of data that must be used in compliance with data privacy requirements. To date, data acquisition has been a largely manual process with strict security agreements and standards that can make it challenging to obtain.
To overcome these challenges, Dr. Frank Loge, director of CWEE and a professor in the UC Davis Civil and Environmental Engineering department, worked with UC Davis’s information technology departments to develop a new secure, shared system using a range of AWS services. The new system protects sensitive research data, makes clear who is responsible for protecting it, and verifies compliance. The system has garnered new interest and funding opportunities and has the potential to help spur new innovations in the water sector, driven by broad access to data.
A recent case study by the Western Cooling Efficiency Center (WCEC) seeks to answer: does making your own portable air cleaner match the cleaning performance of off-the shelf products and do so in a cost effective way?
Portable air cleaners are increasingly in demand to reduce concentrations of particulates and respiratory aerosols indoors. Researchers at the UC Davis Western Cooling Efficiency Center (WCEC) tested two types of Do-It-Yourself (DIY) portable air cleaners (standard box fans modified with added filtration on the suction side of the box fan) and documented the power draw, airflow, and noise for each configuration. Researchers calculated the clean air delivery rate based on filter test reports and reported energy efficiency and cost metrics for each configuration.
Note that while DIY portable air cleaners are a useful and easily accessible tool to reduce particulates in buildings, they should not be considered a substitute for ensuring adequate ventilation and filtration is provided by central building heating, ventilation, and air conditioning (HVAC) systems.
Watering the lawn less, taking shorter showers, and switching to a low-flow toilet all conserve water. And they also reduce carbon pollution. “About 20% of the state of California’s energy use is associated with the water system,” says Frank Loge of the University of California, Davis.
He explains that every step of a water system uses energy: pumping water from lakes and reservoirs, treating it to make it safe to drink, and pumping it into homes and businesses. Then, if it’s sent down a sink or toilet, it’s usually processed at a wastewater treatment plant, which Loge says takes a tremendous amount of energy.
On October 19-20, 2021, UC Davis will host the third Global Energy Managers Workshop, where facility managers, students, and faculty from around the world will meet to share and learn about energy-saving, cost management, and carbon reduction strategies.
This year’s event will be online via Zoom. We have an exciting agenda and hope you can participate.
For more than 25 years, Tom Smith has run 3Flow, a company whose sole mission is to make sure people don’t get sick from airborne hazards in their workplaces.
He suddenly has the attention of a lot of employers who never really gave thought to it before the pandemic.
Typically, Smith’s team focuses on how the air moves through places like labs or factories, but since the pandemic started, his business has been getting calls about open layout offices, conference rooms and auditoriums.
“A lot of people have found out that their systems are dysfunctional,” Smith said.
Office spaces are often a lot harder to work with than labs, Smith said, because they weren’t designed with floating pathogens in mind, and the systems have not been well maintained. He says there’s a simple reason for that: it wasn’t required.