As the market searches for clean energy alternatives to control indoor environments, cost-effectiveness comes into play. Research by the American Council for an Energy-Efficient Economy (ACEEE) points to electric heat pumps as the best option in most locations.

Published in July, the “Analysis of Electric and Gas Decarbonization Options for Homes and Apartments” finds that electric heat pumps will minimize the equipment and fuel costs in all but the coldest environments.

Electric heat pumps are energy efficient because they don’t create heat by burning fuels. Instead, they move warm air (during the heating season) from cold outdoors to warm indoors. Cold-climate models, an advance in technology, operate efficiently at temperatures as low as 5°F. Their energy costs, however, are minimized if an alternative fuel backup kicks in when it gets colder than 5°F for long periods.

The ACEEE study evaluated the energy use of about 3,000 homes across the United States. It considered life cycle costs for equipment and energy under a scenario in which the electric grid and heating fuels are largely decarbonized, meaning they run without fossil fuels, beginning in 2030.

To make this evaluation, the study used a metric known as heating degree days (HDD), which compares the mean outdoor temperatures recorded to a standard temperature, usually 65°F, for a particular location. The more extreme the outside temperature, and the greater number of days when temperatures fall, the higher the number of degree days for the time period measured, such as one year. A high number of degree days generally results in higher levels of energy use for space heating.

The study finds that for homes with up to four units, electric heat pumps generally minimize heating and cooling costs in places that have fewer than 6,000 HDD, or in geographical terms, are “warmer than Detroit.” In colder climates, the study finds that electric heat pumps combined with use of a backup fuel during frigid periods (below 5°F) generally minimizes these costs.

ACEEE is not just blowing hot air. It notes that electric heat pumps are also more efficient at delivering other types of climate control. For example, the study finds the technology minimizes costs for water heating in all climates.

It also notes that as global warming causes average temperatures to rise, heating needs will diminish and the demand for cooling will start to rise. In this scenario, the study also finds that “electric heat pumps can efficiently meet these needs in all climates.”