ACEEE Research Report Shows Heat Pumps Help Decarbonization of Residences

An extensive investigation into the management of power to domestic users shows that in many circumstances heat pumps are the best option for space and water heating. The American Council for an Energy-Efficient Economy (ACEEE) is a non-profit research organization, which surveyed several thousand homes across the USA. They looked at various decarbonization options, and heat pumps stood out as generally the best method.

As climate change bites and many areas suffered record heatwaves this year, states and utilities need to ensure long-term commitments to decarbonization. Buildings are responsible for around one-third of U.S. greenhouse gas emissions. There are many possible avenues to improve home power usage, and greater efficiencies will benefit utilities as they have to manage diverse loads in an expanded electric infrastructure.

The report found that in many homes – both detached and attached – electric heat pumps generally minimize average life-cycle equipment and energy costs for heating and cooling in places with fewer than 6,000 heating degree days (HDDs), which is areas south of Detroit. In colder northern states, electric heat pumps with an alternative power source when temperatures drop below 5°F generally minimize these costs.

These results assume installation of cold-climate electric heat pumps in places with more than 4,000 HDDs (the recent climate in Maryland and northern states). These are the newest and most advanced heat-pumps on the market. They work in cold-climates and can provide heat at temperatures down to about 5°F. The ACEEE's analysis suggests users can best minimize lifecycle costs by utilizing cold-climate models in places that are both cold (4,000 HDD to 6,000 HDD) and super cold (6,000-plus HDD).

For larger buildings, the installation of heat pumps may not be practical or cost-effective. The ACEEE suggests, with limited data available, that using alternative fuels in condensing boilers and furnaces could minimize life-cycle costs.

For water heating in single family up to to four-family homes, electric heat pump water heaters (HPWHs) have the lowest life-cycle costs in all parts of the United. States, followed by gas-driven HPWHs and then gas condensing tankless water heaters.

Most of these improvements will be to existing homes. Retrofitting energy efficiency measures usually incur greater costs than with new buildings designed with advanced technology in mind. For many homes, a moderately-sized energy efficiency package (based on Home Performance with ENERGY STAR®) has the lowest life-cycle costs, but for some system types and homes, a deep retrofit at the time of building renovation often reduces life-cycle costs, particularly for residences with above-average energy bills and dwellings in colder climates.

Depending on the cost of equipment, and energy costs, the savings may vary. The survey looked at results by region:, electric heat pumps are more likely to minimize life-cycle costs for houses in the South and along the Pacific coast and least likely in the Midwest, with other areas having modest savings.

As the country transitions to decarbonized buildings, electrification will be needed in most places and alternative fuels in very cold places. This is dependent on fossil fuel prices; when they are low, there are no incentives for people to change. Now they are rising rapidly, there is an incentive to move to more efficient sources of power. Obviously Government policies—including research and development, minimum efficiency standards, incentives and grants, restructuring electric (and perhaps gas) rates, clean heat standards, and a price on carbon—will help accelerate the transition's progress.

The report's findings show that advanced heat pumps could make a significant difference to GHG emissions and power requirements in many parts of the USA, including those area which have a colder climate. This assumes that programs will be available to defray capital costs for poorer demographics, as heat pumps are a significant capital outlay.

Access the full report here.