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While it’s widely accepted heat pumps can keep homes warm in regions that don’t experience extreme cold, their performance in chilly parts of the world is frequently debated. A new paper out of Oxford University has put much of that skepticism to rest.

Heat pumps work by absorbing heat from the air outside — the colder it gets, the harder the units have to work to keep spaces warm. That’s where the doubt comes in: if heat pumps have to work overtime to produce energy, are they really better than other heating sources?

Published Monday in the scientific journal Joule, the research found heat pumps are two to three times more efficient — or, use two to three times less energy — than their oil and gas counterparts, specifically in temperatures ranging from 10 C to -20 C.

The research debunks misinformation often spread about heat pumps, says Duncan Gibb, senior adviser with the Regulatory Assistance Project, an international NGO focusing on energy, which published the peer-reviewed paper with Oxford.

While a heat pump will have to work harder during sub-zero temperatures, it will still be more efficient than other sources of heat, explained Gibb.

The gas industry in Europe and the fossil fuel industry in Canada try to use the efficiency drop heat pumps have in cold weather as an argument to disqualify them as a practical home heating source, Gibb said.

Not so. “Their efficiency doesn't decline to such levels where they're disqualified,” said Gibb, who is from Nova Scotia but now lives in France.

The paper, which collected performance data from studies across Europe and North America, found standard heat pumps are two to three times more efficient in places that typically reach up to -10 C, while cold climate heat pumps are 1.5 to two times efficient to up to -30 C.

People who live in chilly places shouldn’t rule them out as an option, nor should federal and provincial governments when considering what forms of heating to advocate for, said Gibb.

Published Monday in the scientific journal Joule, the research found heat pumps are two to three times more efficient than their oil and gas counterparts, specifically in temperatures ranging from 10 C to -20 C. 

The graph below shows blue dots, representing data from studies collected by the researchers. The information they pulled all used the average coefficient performance, which measured how efficient the heat pump is, and the average outside temperature from varying kinds of heat pumps. The coefficient measurement shows a spectrum of 100 per cent efficient to 600 per cent efficient. If a heat pump is 200 per cent efficient, that means it’s transferring double the amount of energy it uses.

Graph courtesy of authors

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 and 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.

Heat pumps run on electricity, like electric heat, and depending on where you live, the energy varies in cleanliness. In British Columbia, most of the energy produced comes from hydropower, while in Nova Scotia, it comes from a mix of natural gas and coal. Because heat pumps use far less energy than other forms of heating, it makes them better for the planet.

Efficiency measurements don’t measure comfort, explained Gibb, but he said there are consumer surveys showing those who use heat pumps fare well in cold temperatures. A 2022 consumer analysis in Europe found 81 per cent of respondents said their comfort improved after installing a heat pump. Another study conducted in New York and Massachusetts, which installed monitoring equipment in heat pump users' homes, found 32 of the 42 people who participated said they were more comfortable post-heat pump.

While Gibb hopes the study might change the minds of people concerned about heat pumps operating in cold weather, he said it also stresses the need for more supports for low-income people to install heat pumps to save money and limit emissions. 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. In June, Efficiency Canada called for a tenants' bill of rights in a paper that digs into the inequity renters face around gaining benefits from efficiency measures such as heat pumps and makes policy suggestions on how Canada could lead the way by marrying rental protections with energy-efficiency programs.

Examining the big picture of data available on heat pumps proves they can play a much greater role in Canada and beyond, Gibb said. Yannick Monschauer, an energy analyst with the International Energy Agency, agrees.

"Thanks to continuous efforts on research and development — including by collaborators within the IEA’s Technology Collaboration Program — manufacturers have developed specialized heat pumps that work very efficiently in cold climates,” said Monschauer.

“Worldwide, the share of heat pumps in heating equipment sales is set to more than double by 2030 under today’s policies, as deployment also accelerates in colder climates."

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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costco is selling premium heat pumps ( good to -30) for $1500! the expensive part is the electrician to install it properly into your home electric system. ( unless you’re a DYIer)

Awesome! Both my kids have them including one that lives in the interior of BC where it gets to -20° or more in the winter, and both love them. Set to a specific temperature that everyone finds comfortable and that’s the temp it keeps the house summer and winter!

Now that the efficiency of a heat pump vs electric heating has been covered can we have an article stating the total costs involved ? Note the cost of electricity is the energy rate plus delivery plus taxes.

I very much appreciate reading more coverage of heat pumps; I've been advising a neighbour, recently, and better information is helpful.

One paragraph from the actual study is worth pointing out, as it will scare away many people, I think, who have the slightest skitteshness regarding change.

"In extreme cold climates, such as where the lowest temperatures approach −30°C, performance data have shown that heat pumps can provide heat at efficiencies up to double that of resistive heating; however, more analysis is required."

Here in Ottawa, we don't get that many really cold winter days, but we remember that it gets cold. Also, in the main, we heat with gas, not resistance heat. "Further analysis required" also doesn't foster the "warm fuzzies".

Additional doubt is introduced by the inconsistent messaging, and switching between a "standard" heat pump and a *cold climate" heat pump. In this regard, this article had two things which caught my eye:

1. The scatter diagram measuring efficiency against temperature (its not clear if all the data was sourced from the same class of pump; a quick look at the study confirms the data was from every type of pump), plus the lowest temperature charted was -20.

2. The phrase "while cold climate heat pumps are 1.5 to two times efficient to up to -30 C" muddies the water by not suggesting how one ought to determine which class of pump is needed (perhaps beyond the scope of the article but we need a clear, concise guide to selecting between standard and cold, with additional guidance on supplementary heat for very cold days).

The study authors didn't help their cause, IMO, by, on the one hand, stating that their commentary focused on mild winter locations while, on the other hand, subsequently making the following observation:

"Field testing was also conducted in Alaska by the Oak Ridge National Laboratory (US4) using a cold-climate air-source heat pump.11 These tests found that the COP remained relatively high, achieving 2.0 at −25°C and 1.8 at −35°C."

Such observation would be very helpful for cold parts of Canada.

In short, heat pump advocates really need to provide an inclusive (across climates and technologies), consistent, easy-to-understand message with fairly clear pivot points between possible solutions.

One other wishlist item:

An inexpensive, simple, VW-not-Rolls-Royce ground-source option.

Another couple of paragraphs from the study introduce more doubt regarding very cold (below -10) conditions:

"The question whether back-up heating is needed for extreme conditions is often raised. Several of the studies included in this commentary, such as (US3), used back-up resistive or combustive heating—or at least had it available in case it was needed. However, back-up heating was typically only engaged when the outside temperature dropped past −10°C or lower. Above −10°C, heat pumps were able to provide the required heat at relatively high efficiency.

From a heat provision standpoint, this suggests that concerns over the need for back-up heating during mild cold climate conditions may be unfounded and the role for hybrid systems may be limited. There is an outstanding question over the role of hybrid systems in the coldest climates, not necessarily because of efficiency performance but because of the high output capacity of heat pumps needed at very low temperatures. Recognizing the limits of focusing only on efficiency, we suggest a valuable route for further research would be to explore the specific value of hybrid-type heating systems."

Let's get that consistent message solidified!

I think you're looking for something that may not exist. A standardized, 100% guarantee that everything will work perfectly. But even with gas heating, which most of us take for granted now, explosions from gas leaks have been minimized but not eliminated.

What's more......I worry that as infrastructure ages, and everything becomes more expensive to procure and implement, aging pipes may blow. We're getting ready to put in a heat pump and seriously: if the weather should suddenly pretend another ice age is upon us......we'll use electric heaters, and our high efficiency ride out the blip.
Another quibble I've seen that might be a harder hurdle to cross is the complaint that the heat pump makes a constant low level noise. How serious is that sound? Because I understand heat pumps are always or cold.

I think you're misunderstanding what it is I'm looking for, Mary.

I'm not seeking a system that's more reliable than an a median furnace/ AC in an average home; I'm seeking clearer guidance from the industry on the type of system that's the best bet for the different climactic regions of the country. It doesn't need to be perfect. Right now one can receive guidance on the sort of furnace/ AC that one needs, based on, e.g., volume of air in one's house; degree days; highest/ lowest temperatures. Pretty straight forward.

In Ottawa, for example, according to the study, one could likely make do with a cold climate heat pump alone (of sufficient size, based on air volume and, say, how tight the house is sealed), or perhaps a smaller capacity c.c. pump might be sufficient with gas or electric back-up for very cold days. Basic stuff.

We've had our heat pump for 6 years now and it has performed as hoped down to -15C (as cold as it gets here). And it keeps us cool in summer heat waves. What's to complain about?!