What is it?
Air-source heat pumps provide heating and cooling in lieu of furnaces and split system, “central air conditioning”. However, in cold climates like that of the Midwest, heat pumps may have problems with meeting heating loads when outdoor air temperatures are 32oF or colder. Below these temperatures, most heat pumps enter an electric resistance heating mode, which is 20-33% the efficiency of its regular heating operation. New cold weather, or low temperature, heat pumps are designed to operate efficiently without electric resistance heat at much lower temperatures, often down to 5oF or lower.
How does it work?
Heat pumps have been around for many years, but recent improvements in some of their components have allowed them to operate at lower temperatures. These include: variable-speed compressor motors, improved refrigerants, better controls, larger heat exchangers, and more precise valve actuation.
What are the most appropriate applications?
The best applications are spaces currently heated by oil, propane, or electric heating sources that also require cooling and do not have access to steam or hot water lines.
What are the savings?
Savings will depend on the size of the heat pump and the existing heating and cooling fuel source. In a large study in New England, cold weather heat pumps in homes saved 3,000 kWh over electric resistance heat (57% reduction in energy costs), and 50% in operating costs over oil heating. Energy savings for a two-and-a-half-ton low temperature heat pump over a standard unit can range from 500 to 1,000 kWh, or 11-22% cost savings.
What are the non-energy benefits?
They allow for heating and cooling to be provided to spaces where duct work would be expensive or impossible to install.
What is the cost?
Costs for these heat pumps range from $3,000 – $6,000 per unit for 0.75 to 3-ton units, with costs increasing with capacity. The incremental cost over standard heat pumps is typically near $1,000.
What is the status/availability of the technology?
This technology is readily available through multiple manufacturers including Carrier, Daikin, LG, Mitsubishi, Fujitsu, and others.
What kinds of incentives/programs are available?
Heat pumps qualify for prescriptive incentives for many utilities. These incentives will vary depending on the existing fuel type and the size of the unit. However, many prescriptive rebates do not include additional savings for low temperature operation, so a custom rebate may be necessary to capture the full savings.
 Energy savings for low temp ASHP over standard unit were calculated using our own calculation template.
 Incremental cost estimated by using Vermont’s cold climate heat pump rebate of $300 and assuming that this refunds 30% of the incremental cost of the unit. Thus, the total incremental cost is $1,000. Also, page 37 of the Market Strategies report shows $4,096 for total cost for cold climate heat pumps, which is about $1,000 above a standard heat pump cost of $3,000.