Home heating is the largest energy expense for most U.S. homeowners and accounts for nearly 30 % of energy used in the nation’s residential buildings. Millions of homeowners in colder regions with cold climate of the country do not have natural gas available, leaving furnaces to be fueled with heating oil, propane, or electricity. This can often result in higher heating bills for homeowners.
But today there’s an option that could heat your home better, reduce your heating bill, and improve your comfort at the same time. Air-source heat pumps (ASHPs), commonly used across the southern parts of the country where winters are relatively mild, are now becoming capable of delivering heating even in cold regions such as New England and the upper Midwest.
How it Works
Air source heat pumps work like refrigerators – but in reverse, absorbing heat from the outside air at low temperatures into a fluid, which is passed through a compressor where its temperature is increased, and at its highest temperature transfers heat to the heating and hot water circuits of a home. Across all heat pump types, because heat is moved rather than generated, heat pumps can provide equivalent space conditioning at as little as one quarter of the cost of operating conventional heating or cooling appliances.
In the past, the heating capacity and efficiency of conventional ASHPs decreased significantly as the outdoor temperature dropped and the demand for home heating rose – resulting in inefficient and insufficient performance that required additional heating sources to stay warm. In part thanks to DOE research, ASHPs today can reduce electricity use for heating by approximately 50 % compared to electric resistance heating such as furnaces and baseboard heaters.
DOE Research Finds Solutions
The Building Technologies Office within EERE funded research to develop a prototype cold climate ASHP. Emerson, in partnership with Oak Ridge National Laboratory, developed a prototype that is both cost-effective and highly efficient at heating the home. The heart of the prototype is a new scroll compressor, which is optimized for low ambient heating performance. The design used tandem compressors and other features to achieve its target performance, which allow the first compressor to provide cooling and heating functions in mild common conditions, but when outdoor temperatures drop, both compressors kick in and comfort is maintained.
This prototype was field-tested in both Ohio and Alaska to ensure it worked as designed. Dan Knoth, a senior project engineer with Emerson Climate Technologies, housed this cold climate heat pump in his Ohio home for the last three years. In Tipp City, Ohio, the temperature varies winter to winter but it’s common to have one month where the days are below 25 degrees. By comparing the coldest months year to year, Knoth found a 30% reduction in his bill. When outdoor temperature plunged, the prototype kept the house warm and comfortable without any reliance on supplemental electric resistance heat.
How it can help consumers
Here are just a few reasons why cold-climate ASHPs can be beneficial for consumers:
- Provides Cost and Energy Savings. The Northeast Energy Efficiency Partnerships found that when entire heating units are replaced in the Northeast and Mid-Atlantic regions, the annual savings from an ASHP can be over $450 compared to electric resistance heaters or over $900 when compared to oil systems.
- Multiple Models Available – For Cold and Mild Climates. With increasingly energy efficient models available on the market, the energy savings from ASHPs can really add up over the winter. Consumers should look for the ENERGY STAR label when choosing an ASHP – and for those in colder climates, they should focus on getting the highest heating season performance factor (HSPF) possible. In warmer climates, choosing a model with a higher seasonal energy efficiency ratio (SEER) is more important.
- Installation Benefits from Single Package. Unlike ground-source heat pumps (GSHPs), ASHPs can be installed in a single package that doesn’t require extensive digging or underground installation. When used in a well-insulated and weather stripped home, an ASHP that has been properly sized and installed can offer similar performance – with lower up-front costs – to GSHPs.
- BTO is continuing to research heat pumps across technology classes. For example, it is still conducting R&D into expanding the performance natural gas cold climate heat pumps as well, and has made current awards to continue those investments.