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Ryan Kelly was already a heat pump advocate when he installed one in his almost century-old home a couple of years ago, but even he was surprised at how well it performed during a cold snap last winter.

Temperatures plummeted to -20 C at Kelly's home in Halifax this past February. Kelly works for Efficiency Nova Scotia — a non-profit that manages rebate administration for provincial and federal energy programs (such as the Greener Homes Grant) and electricity efficiency and conservation activities for Nova Scotia Power, the province’s private utility — and enjoys crunching numbers. So, he installed monitoring equipment in his energy panel to chart how efficient his heat pump was in extreme cold.

Before he put in the heat pump, Kelly’s house ran off electric heat. Making the switch means he avoids associated emissions that come from using just an electrical heating system, which takes energy from the grid. In Nova Scotia, that mostly means a mixture of coal and natural gas-fired power. While heat pumps also use electricity, they use much less.

“So this is really the coldest temperatures you see in Nova Scotia. This particular unit was operating at 182 per cent efficiency,” explained Kelly.

Heat pumps operate at over 100 per cent efficiency, which means they transfer more energy than the amount used to power them. They work by drawing heat from a source, in this case, the outside air, which means when it gets especially cold, the system has to work overtime to heat the house.

The fact that Kelly’s heat pump operated at 182 per cent efficiency at -20 C showed it was still producing much more energy than it used, meaning he was still saving energy and money.

Chart by Ryan Kelly

Ryan Kelly was already a heat pump advocate when he installed one in his almost century-old home a couple of years ago, but even he was surprised at how well it performed during a cold snap last winter. Here's the data behind its performance.

Heat pumps, which act as heaters in the winter and air conditioners in the summer, are becoming an increasingly popular swap for homes running on natural gas — or as is common in Atlantic Canada, oil. Heating systems that use fossil fuels can reach up to 98 per cent efficiency, while heat pumps can be 200 to 540 per cent efficient because they transfer heat rather than generate it. Since they use much less electricity and don’t run on fossil fuels, they are a way to limit emissions, especially as Canada moves towards its goal of a net-zero building sector and net-zero emissions by 2050.

For all of their energy-saving achievements, heat pumps elicit skepticism. There is an unfounded belief among some that heat pumps can’t adequately perform in cold winter temperatures experienced by much of Canada.

However, heat pump technology is improving, and energy experts dub the cold weather argument a myth. A study by the Yukon government, for example, showed heat pumps operating efficiently at up to -28.9 C.

Kelly’s heat pump uses his home’s central duct system installed when he had an electric furnace. The heat pump was able to repurpose the existing duct and vent infrastructure to blow hot and cold air into rooms throughout his 1930s home.

“We did a lot of building envelope upgrades first, which is the line that you hear from energy efficiency people: attack your building envelope first,” said Kelly, referencing efforts to allow less air to escape through a home with upgrades such as high-efficiency windows.

When using a central duct heat pump system, people often have a backup heat source, which could be oil, gas or electric. In Kelly's case, his electric furnace kicks in if the heat pump can’t meet energy demands. It came on intermittently during the coldest period of the coldest day when the heat pump was in its defrost cycle.

In Kelly’s eyes, using his backup electric heat for a few hours a year spells success. Each year, he saves approximately $1,400, if using a price of $0.16/kWh, the current electricity rate in Nova Scotia.

When looking at areas that experience many days of -20 C temperatures and below, Kelly said heat pumps can still operate well. According to Natural Resources Canada, cold climate air source heat pumps can work down to -25 C and people who make the switch to them from oil can save between $1,500 and $4,700 per year on home energy bills.

He acknowledges backup energy sources are often used in cold climates, but that even if the heat pump is covering a portion of your energy needs, there are still financial and climate benefits.

Heat pump adoption soaring in the Maritimes

Overall, heat pump adoption has soared in the Maritimes. The Canadian Climate Institute notes that New Brunswick saw heat pumps as the primary heating source in 32 per cent of homes in 2021, compared to 17 per cent in 2017. In Nova Scotia, they were at 21 per cent in 2021, compared to 14 per cent in 2017. In Prince Edward Island, they jumped from nine per cent in 2017 to 27 per cent in 2021.

The Canadian Climate Institute chalks those numbers up to a few factors. The region as a whole experiences high levels of energy poverty, which is when you spend a disproportionately high percentage of income on home energy bills. A report from Efficiency Canada found that 41 per cent of residents in Prince Edward Island are dealing with high energy cost burdens.

Compared to somewhere like British Columbia, where almost every region uses natural gas as its main heat source, the Maritimes use mostly oil-burning furnaces and electric baseboards.

“In the case of heating oil, predominant in Nova Scotia and P.E.I., prices are volatile. In the case of electric baseboards, predominant in New Brunswick, large electrical panels already exist in typical homes and can be adapted for heat pump systems without significant new wiring or costly upgrades,” writes the Canadian Climate Institute.

Those factors, combined with provincial incentives that bolster federal ones, show that strong financial support can accelerate adoption. In P.E.I., the province offers free heat pumps to people with an annual household net income of $75,000 or less; Nova Scotia has similar funding.

Updates and corrections

| Corrections policy
September 13, 2023, 08:00 pm

This article has been updated to more accurately describe how a heat pump transfers heat. The unit does not create energy, as previously stated.

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Just finished books by Vaclav Smil where he goes on about insulation and windows. I didn't know just how very, very much better it is to splurge on windows, in the long run. Get triple-glazed and coated with argon gas between. That, good insulation, and caulking, it's like getting a whole other furnace.

Actually, it should be illegal to build below that standard from now on. "Passivehaus" is a tall order in Canada, but "at least 80% Passivehaus" should be a standard.

It was an exciting article. I especially enjoyed the graph of the actual measurements Ryan has made. Thanks for sharing.

All your credibility vanishes with "heat pumps create more energy." Energy can neither be created nor destroyed, and that is the foundation of science. Heat pumps make that -20C outside air even colder, and concentrate that heat for the home. Their job is to keep one side hot and the other cold, but the bigger the necessary difference, the harder they have to work. There is also the whole field of heat pumps that don't use the outside air as a heat source, but something much warmer, such as the ground and water under the snow. I am letting my CNO subscription run out.

Splitting hairs. The meaning was completely clear.

This story, along with a new study published by Oxford University researchers, shows that cold-climate heat pumps are energy efficient even down to -30C. Most of our population is distributed along the 49th parallel where temperatures rarely dip into the -20-30 C range. Consequently, heat pumps should be the first choice for heating (and cooling) for the vast majority of Canadian homes and businesses.

It looks like it approaches zero efficiency below -20 degrees. Which is OK, I guess, when historically you don't get -30 degrees in as many winters as not. Then, too, with everyone using heat pumps and the outdoor air being colder in winter, that's bound to make for a lower temperature in urban settings. Just like A/C makes the air hotter in summer.

Anyone in southern Ontario who's paid close attention to the weather forecasts (usually much more informative than radio or TV news) will have noticed how blessed Toronto is to be on the lake, and will have had proof of the temperature modifying effects we learned about at middle-school age, back in the '50s.

We were much more aware of the temperature modifying effects of trees, because they were part of our regular experience.