Carbon Switch founder Michael Thomas debunks the myth that air source heat pumps (ASHPs) don't work in sub-zero temperatures.
One of the most common questions I get at Carbon Switch is “Do heat pumps work in cold weather and climates?”
Google this question or ask a contractor and you might think the answer is no. But make no mistake, heat pumps absolutely work in cold climates. Not only that, but often they are the most energy efficient and cost effective solution available.
A few decades ago, most heat pumps stopped working when the temperature dropped below 20 or 30 degrees fahrenheit. By contrast, today’s heat pumps can run more efficiently than any other HVAC system all the way down to about -25 fahrenheit.
Just ask the millions of homeowners in Scandinavia. People in Norway, Finland and Sweden are installing heat pumps at a faster pace than anywhere else in Europe.
You might be thinking, “Scandinavians do everything better than the rest of the world.” But some states in America are actually adopting heat pumps at an even faster rate than the countries listed in the chart above — even some of the ones with the coldest climates.
Last year, in Maine, there were 50 units sold per 1,000 households, inching it just a little higher than Europe’s leading country, Norway. By comparison 23 units were sold per 1,000 households in the rest of the United States.
There’s compelling evidence that heat pumps can save most homeowners a lot of money too. I recently used data from NREL’s ResStock model to see how much money the average homeowner can save by switching to a heat pump in various states. I discovered that the average homeowner in Maine — to use my favorite cold climate state as an example again — could save $718 per year.
In New York, a far more populous cold climate state, the average homeowner can save $637 per year. The millions of homeowners using fuel oil in the state could save $976 per year.
I could go on and on. Pennsylvania: $935. Massachusetts: $838. Ohio: $676. You get the point. There are a lot of cold places in this country where heat pumps are simply the best way to heat a home and save money in the process.
The three myths of cold climate heat pumps
But why are there still so many contractors and homeowners that think heat pumps don’t work in cold climates? My theory is that three myths are to blame:
- The capacity myth, which argues that heat pumps can’t produce enough heat to keep your home comfortable in cold weather.
- The efficiency myth, which argues that heat pumps lose their efficiency advantage when the temperature drops.
- The money myth, which argues that due to their lower efficiency in cold weather, heat pumps cost too much money.
To be clear, these are all myths. But like many falsehoods, their origins stem from seeds of truth. Sometimes the capacity of a heat pump doesn’t meet the load of a home. In some climates and homes it isn’t as cost-effective to use a heat pump.
In the rest of this article I want to debunk each of these myths. But I also want to go beyond the black and white answer and explore why some heat pumps work in cold climates and others don’t.
Read the full article on Carbon Switch