Energy efficiency saves money over the long haul, by making use of what was going to waste. On a large scale, it can cut the need for expensive energy-generation projects. And it fuels a lot of jobs in California.

That sort of information means a lot considering what we think will be an emphasis on coal and oil under the incoming administration of President Donald Trump, who has promised returning jobs to coal miners and oil drillers.

We think that’s the wrong approach when considering the environment, continuing need for more energy and developing more jobs.

A new report from the group Environmental Entrepreneurs (E2) says 321,177 Californians work in energy-efficiency jobs — half of them for companies with one to five employees.

The biggest share of those jobs — 46,620 — belongs to the Los Angeles-Long Beach-Santa Ana metropolitan area. Ranking No. 2 is the San Francisco-Oakland-Fremont area with 25,611.

Across the United States, about 1.9 million workers are employed in energy efficiency, E2 found, a 13 percent increase over the previous year. Roughly 70 percent of them work in companies with 10 employees or fewer, so this is an “industry” of small businesses.

And providing the future employees to that developing industry is happening right here in Yolo County, where UC Davis has been actively involved on the front lines of energy research.

Let’s look at this past month alone.

•Two years after Colorado legalized recreational marijuana in 2012, grow houses consumed about 2 percent of the power supply in Denver alone. In California, we’ll see grow houses doing the same thing now that a new law allows recreational use of marijuana. Don’t laugh. This is quite serious. In anticipation of this new demand, a team of researchers from the Western Cooling Efficiency Center at UC Davis is testing equipment designed to reduce the energy demand of this rising new industry. The researchers developed a model of a typical grow house and tested a new dehumidifier built by the New York-based company MSP Technology. The scientists found the system could save 30 percent to 65 percent of the energy a grow house uses for dehumidification and cooling. It also reuses 100 percent of the water it removes from the air to water plants.

•A team of UC Davis students are tackling the California drought through housing design with their entry for the U.S. Department of Energy’s 2017 Solar Decathlon. The design focuses on cutting typical residential water use in half while maintaining the same level of comfort at an affordable price. The home design’s features include systems for rainwater catchment, graywater and blackwater re-use, and a two-way communication system to monitor water and energy consumption.

•The U.S. Department of Transportation also just announced its selection of the National Center for Sustainable Transportation, led by the UC Davis Institute of Transportation Studies, to receive a five-year grant totaling about $14 million to advance a more sustainable transportation system, which means using less conventional forms of energy (ergo gas and oil) to get us from here to there.

And these activities don’t include making solar energy cheaper and developing other forms of alternative energy such as wind and hydrogen power.

It’s demonstrable that energy efficiency saves money for consumers. The report states that Californians’ monthly electric bills have gone up just $4.25 since 1990, adjusted for inflation; meanwhile, in Wyoming, where little investment is made in energy efficiency, the increase has been more than $16. Our state’s consumption of electricity has grown just 1 percent annually, while natural gas consumption has remained flat, according to the California Energy Commission.

Efficiency upgrades are particularly beneficial for low-income households, not only because they spend a larger proportion of their income on energy, but because those households often live in places with poor insulation and old, inefficient appliances, the E2 report points out.

Long-term savings for residents and businesses and 320,000-plus jobs and growing make energy efficiency a valuable industry for California.