Absolutely – there is plenty of evidence that heat pumps definitely work in cold climates. Let’s take a look at heat pump adoption in very cold regions.
Norway, Sweden and Finland have some of the coldest winters in Europe, and yet today they lead heat pump ownership per capita – 60% of Norwegian buildings and more than 40% of Finnish and Swedish buildings use heat pumps (echoed by the EHPA). This is proof beyond any doubt that heat pumps can be used efficiently in very cold climates.
Not only do heat pumps work in very cold places, but they also make more financial sense there too. The greater your heating needs, the greater the potential savings from using a heat pump.
Why is the ability to use heat pumps in cold regions doubted?
The truth is that up until 10-15 years ago years heat pumps were not ideally suited to handle extremely cold outdoor temperatures such as those faced in the Northern regions such as in Scandinavian countries, Canada, Alaska, Russia and so on. Things have changed a lot since then. Modern heat pumps can perform very well in really cold climates and we’ll take a look at how they do that in a bit.
Another reason this defunct view is still shared is because of how heat pumps work.
Heat pumps extract heat from the outdoors and move it indoors. A common misconception is that it must be relatively warm outside to move heat indoors. A heat pump can take the outside air and absorb heat from it even if the temperature reaches -25°C or even -30°C.
Not all heat pumps are capable of operating in such conditions though. The “cold climate” heat pumps that have emerged, work well in cold climates without needing a backup system. Not using such a system in a cold environment could result in poor reliability and performance.
How do heat pumps work in cold climates and cold weather?
Heat pump technology advancements over the past years have significantly bolstered their ability to perform efficiently in extremely cold climates.
Compressors and fans
Variable-speed fans help circulate heat better compared to fixed-speed fans.
Standard compressors typically work at a specific speed and can be either switched on or off. When the heat pump is in operation, they will switch on and off as needed so as to maintain a certain temperature dictated by the thermostat inside your home.
Inverter-driven heat pumps use both variable speed compressors and fans, which makes them both powerful and efficient during the cold days of the year.
Flash-injection technology
Flash-injection technology allows far greater efficiencies and lower operating temperatures.
Normally, the refrigerant loop collects energy from the outdoors to transfer it indoors.
The flash-injection process operates in a distinct manner. According to Mitsubishi, “This unique new system optimises refrigerant flow in low ambient conditions by bypassing some of the refrigerant to the compressor through a flash injection circuit to maximise the heating efficiency and increase the heating range“. This helps the compressor operate at faster speeds, resulting in greater heat exchange.
Advanced defrost cycles and controls
Advanced defrost cycles are optimized for colder climates and protect the heat pump from freezing up. Controls are also designed to handle the colder conditions by making incremental adjustments to the unit’s operation.
Larger evaporators
The larger an evaporator is, the more heat it can extract out of the air outside your home. A larger evaporator doesn’t only result in greater efficiency. When equipped with larger evaporators, heat pumps can keep homes in cold climates warmer under extreme conditions.
Are heat pumps powerful enough for extremely cold places?
OK, so now we’ve established that heat pumps actually work even in cold, extreme environments. But can they produce enough heat to keep you warm in your home or business? Can they still heat to a degree of comfort and do so efficiently?
Yes they can. Heat pump efficiency is largely a product of proper sizing and installation. When an HVAC installer designs a system, they will take many things into consideration when calculating the necessary size of the system. These calculations certainly take into account the site’s climate as well as the building’s insulation among other factors.
As a result, the system is designed from the beginning to be able to put out the right amount of heat for the building under the expected cold conditions.
If a heat pump in a cold climate fails to provide enough heat, it’s almost certainly due to improper sizing and installation.
Do cold climate heat pumps need a backup heating system?
Electric resistance heating is sometimes used as an auxiliary or backup heating system for heat pumps. This is something sometimes found in heat pumps not designed for cold climates. The purpose of the emergency heating feature is to boost the less capable heat pump so that it can cope with the colder climate temporarily.
This premise has led to some installers combining a traditional heating system as a backup to a heat pump, or as a complementary system.
Heat pumps do not require backup heating for the vast majority of homeowners. While indeed some older heat pump units could not reliably heat a home in extremely cold conditions, this is far from true for heat pumps sold over the last decade or so.
In very few extreme cases where heating is deemed essential, and the environment is extremely cold it may be prudent to have a backup system – but this is the case for any other heating system. One great advantage of heat pumps in this situation is that they can coexist with older systems that they are meant to replace.
It’s worth mentioning that heat pumps can reliably provide heating at lower temperatures than some coal, gas, or oil powered solutions, without losing efficiency.
Some cold-climate heat pumps such as a TermoPlus Hydrobox or Hydrotank paired with a Mitsubishi Zubadan could even provide reliable heating in extreme temperatures as low as -30°C.
When is a backup heating system a good idea?
When the heat generated by a heat pump is enough, you may not want to supplement with any other form of heating that is less efficient – therefore more costly.
For extremely critical applications, an additional source of supplemental heat could add some redundancy for peace of mind. This, of course, would be useful whatever your primary heating system would be.
If you already have an older heating system in place and wish to upgrade by installing a heat pump, you could keep (and maintain) that other system as a backup system and pair your heat pump with it. Modern heat pumps can be programmed to switch over to the backup system when the temperature drops below a certain level.
It is unlikely that a backup system will be cost-effective to use along with a heat pump. Although a cold-climate heat pump is one of the best performing solutions for cold climates, efficiency may drop in extremely low temperatures. Nevertheless, the efficiency will always be higher than gas and oil systems which will be between 70% and 90%. Backup heating is only useful if the heat pump’s operation is completely disrupted for some reason. In that case, you can take advantage of the backup heating option.
Do heat pumps in cold climates lose their efficiency?
A heat pump takes heat out of the outdoors and brings it indoors. The cooler air outdoors is, the harder it gets to efficiently bring in heat from outside. Cold climate heat pumps are designed to produce heat in cold weather but the colder it gets outside, the less efficient they become.
At what point do heat pumps become less efficient? For most heat pumps, any ambient temperature below 0°C is the point where the Coefficient of Performance (COP) drops. For cold-climate heat pumps this can be much lower – for instance Mitsubushi Zubadan split air source units can operate at full heating power even at -15°C. These units can still operate at -25°C but at a reduced efficiency. This makes these units extremely efficient all-year round for most regions of the world. Of course, each heat pump model has a different efficiency curve at different temperatures.
All heating systems perform differently under extreme cold. If you have a secondary heating system, it makes sense to compare the heating efficiency curve of each system to establish at which temperature point you may need to operate both together or switch from heat pump to the secondary system. Another factor that needs to be considered is the energy cost of each system.
How do cold climate heat pumps compare against other heating methods in extreme temperatures?
It’s not only heat pumps that can be affected by extreme cold climates. Let’s take a look at the heating and cooling systems commonly used in cold, harsh climates and see how they compare against heat pumps.
Natural gas furnaces and boilers: The extreme temperatures may make fuel more difficult to deliver to the furnace due to the lower pressure in the gas lines. Heating capacity can be reduced and in some cases there is the potential risk of heat loss.
Propane furnaces and boilers: In cold temperatures, the fuel can thicken or freeze in the storage tanks or fuel lines. Fuel may not vaporize properly, and the storage tank may also be at risk of freezing.
Oil powered furnaces and boilers: Fuel line blockages can disrupt their operation or lower their efficiency. This can happen due to the change in the oil viscosity that occurs due to temperature changes – fuel can even freeze. This can be mitigated by storing fuel in a temperature controlled environment and using fuel specially formulated for cold weather. Access to fuel can be an issue in extreme cold as fuel delivery can be impeded due to poor road conditions.
Electric heating / electric resistance heating: As long as the power grid works there is no risk that these won’t work unless they use water and the water pipes freeze. Keeping all water pipes properly insulated should protect them from freezing. The energy efficiency of electric heating as a sole source of heat is very poor though but can be combined with heat pumps to increase efficiency.
Air conditioners with inverter technology: Essentially air-to-air heat pumps (typically ductless), inverter-driven air conditioning units can operate at reasonably cold-climates. They operate by pushing tempered air into the home instead of using a water distribution system such as radiators or underfloor heating. As a result they offer less comfort. They typically operate down to -15°C with some models reaching lower temps, but they are bound by any limitations a heat pump has.
Fireplaces and pellet stoves: Even fireplaces and pellet stoves can be affected during extremely cold days. Although fireplaces are very rugged and self-sufficient their draft could be affected reducing efficiency. Pellet stoves can suffer from frozen pellets that don’t combust properly.
Almost all heating systems use electricity one way or another: Almost all systems require electricity to generate and circulate heat. In the event of a power outage many of these systems would fail to provide heating unless they are either powered by a well-maintained generator or a solar power plant (keep the panels clear from frost and snow and they should operate down to almost -40°C).
What is a better heat source in cold climates? Ground-source heat pumps vs air-source heat pumps.
Both ground source (GSHPs) and air source heat pumps (ASHPs) are very capable in cold climates. Ground source heat pumps effectively have an advantage over air source heat pumps and that is essentially the heat source they use.
Both types of heat pumps perform great even when temperatures are well below freezing. However, the air outside can get colder than the soil below the ground. Ground source heat pumps will therefore have access to a thermal source that is warmer and more stable throughout the whole year.
As a result, cold climate ASHPs can operate in temperatures as low as -25°C whereas cold climate GSHPs can work even down to -40°C. Both types of system will loose efficiency as they approach their lower operating temperature limits.
Does this mean it’s worth investing in a ground-source heat pump? Not necessarily. GSHPs are more costly to buy and install so unless the conditions are so extreme it is more than likely an ASHP will do the job nicely. This is something that should be considered with the input from a reputable heat pump installer or HVAC engineer.
Are heat pumps worth considering in cold climates?
Yes, resoundingly, yes! Installing heat pumps across Scandinavia has shown that a heat pumps won’t let homeowners down in freezing cold climates. Not only that, there have numerous additional benefits.
- They are the most energy efficient solution for the vast majority of the year, even in extreme climates.
- They are exceptionally reliable and don’t necessarily need backup heating.
- They can be combined with your existing system as a backup heating system for added redundancy.
- They can be combined with solar power plants and battery storage, reducing the risk of power outages during extreme weather conditions.
- They can provide domestic hot water efficiently in very cold conditions.
- They offer excellent climate control that often includes management of additional heating systems.
- They don’t depend on physical access to fuel when road conditions are poor.
- They aren’t susceptible to problems such as fuel pipes freezing or network pressure issues.
- They are resilient and have a very long lifespan.
If you are a homeowner or business owner situated in a cold climate, don’t hesitate to look into the benefits of a new heat pump to heat your home. Heat pumps work in cold weather, and they are the best way to lower your heating bills over the long run.
Check out the true disadvantages of heat pumps to find out the real pros and cons of heat pump ownership and to see which heat pump myths are busted or not.
