​​​​​​​​Heat pumps: do they work in Minnesota’s cold climate?​

Air source heat pumps (ASHPs) have existed for many years, but the most recent generations of heat pumps have made significant improvements to their operations, making them more efficient and reliable for colder climates.

Installing a new ASHP in your home can help you lower energy usage and raise heating efficiency. But do heat pumps work in Minnesota?

Heat pumps can operate at very cold temperatures

Until recently, limitations on the efficiency of heat pumps were due to cold temperatures.  During the colder months in climate zones 6 and 7, which include Minnesota, ASHPs did not operate efficiently. In  temperatures  below 40˚F,  the ability of the heat pump’s refrigerant to absorb and release heat was affected, which  caused the ASHP to work harder and draw more electricity, making it less efficient. 

Due to recent technological advances, heat pumps are now capable of operating in very cold climates.

A recent study conducted by the Center for Energy and Environment, a Minnesota non-profit corporation  that helps individuals and businesses achieve their energy efficiency goals, found that while older ASHP models begin significantly losing effectiveness at temperatures below 40˚F, the newest generation of pumps  operate efficiently at temperatures between 0˚F and - 13˚F​. 

The study also found that in moderate climates at certain temperatures, the newer generation ASHP’s efficiency increased by two to four times compared to that of standard electrical heating systems.

The newer generations of ASHPs, also known as “inverter heat pumps”, are able to function at lower temperatures due to their inverter compressors. Inverter compressors allow heat pumps to operate at different speeds based on temperatures - increasing their heating capacity and efficiency versus older generation equipment.

Heat pumps transfer heat in both directions

The basics of heat pump technology is that it can transfer heat in either direction - it can transfer heat into a space to warm it, and transfer heat out of a space to cool it down. 

Heat pumps are comprised  of two coils (an indoor and an outdoor coil), a compressor and refrigerant.

 For heating in cold temperatures, heat energy is removed from the outside air by the refrigerant in the outdoor coil. The pressure and temperature of the refrigerant is increased by the compressor, transforming the refrigerant into a hot gas. The heat is then released from the refrigerant by the indoor coil as the gas condenses back into a liquid.​

Variable speed compressors also aid in the process by increasing the compressor speed when outdoor temperatures drop.

Minnesotans are already using heat pumps

National sales of heat pumps have been increasing, with heat pump sales surpassing those of natural gas furnaces in 2022. 

In Minnesota, homeowners have already begun using heat pumps. Between 2013 and 2016, the number of ASHPs sold in-state rose more than 25% compared to previous years’ sales, with an estimated 20,000 units sold per year. 

More recently, Minnesota has seen an increase of applications for rebates from utility companies for the use of heat pumps - about 2,000 in 2019, then more than doubling to 4,600 by 2022 according to the Air Source Heat Pump Collaborative.

The Inflation Reduction Act (IRA) has served as an incentive for Minnesotans to switch to heat pumps. The provisions of the IRA provide for a 25C tax credit of 30%​ of the cost for eligible improvements to the home conducted during the year by a taxpaying homeowner.  While the IRA tax credit has a cap of $1,200 per year, an exception is made for heat pumps, which are  eligible for up to a $2,000 tax credit, provided that they meet certain efficiency requirements.

In addition to the IRA tax credits, some utility companies  offer rebates for homes with a secondary heat source, such as a natural gas furnace.