Contrary to popular belief, air source heat pumps work amazingly well in winter, even in very cold climates. In fact, heat pumps are now the best heating option on almost the entire planet. Heat pumps work in winter by extracting heat from outside air (via coolant) and pumping it into your home. In doing so, they act like an air conditioner, but the other way around.
Since terrestrial heat pumps do not exchange heat with outside air, freezing temperatures affect them relatively. However, they require excavations that can be difficult to perform on existing buildings, especially in heavily populated urban areas. Believe it or not, the winter air is still warm enough for the coolant to absorb. In fact, there is still enough heat in the outside air for a heat pump to do its job when temperatures are as low as 5°F.
Your heat pump will continue to work in cold climates, as long as you buy the right one. Every heat pump is different and you'll need the right equipment to make sure your home can get warm throughout the winter. For UK temperatures, this may not be as big a problem as it might be in some places, such as Canada or North America, where temperatures can drop to -30°C. As a German manufacturer, Viessmann has tested its heat pumps in the harsh German winter and elsewhere in Europe.
While air source heat pumps can withstand cold winter temperatures, there comes a point where extreme outdoor temperatures inhibit their ability to operate efficiently. Air source heat pumps are part of a portfolio of solutions that can further NREL's mission of making energy more affordable, equitable and environmentally friendly. Similar to the Alaska study, Winkler is analyzing how the efficiency of a heat pump decreases in colder temperatures and how to properly size a heat pump for a house. Not long ago, heat pumps were considered inefficient during the winter season and it was vitally important to have a backup heating source.
These pumps are an excellent alternative to other heating systems, since they use a relatively small amount of electricity to operate. One advantage of heat pumps in less extreme climates is that they can provide both heating and cooling, with the simple one-valve switch. The air source heat pump that Tom Marsik installed in his home eight years ago was rare in Alaska. If the outside temperature drops too low for the heat pump to produce heat, a backup may be needed.
In Alaska, the most promising technology is a ductless heat pump, which includes an outdoor unit that absorbs heat from the air and an indoor unit on the opposite side of the wall that leads it to the room. But what will happen to a heat pump if it's really cold outside? There's certainly not enough heat in the winter air, is there? For example, if an air source heat pump uses one kW of electricity to produce three kW of heat, the CoP is three. In short, geothermal heat pumps always have enough heat to absorb and their CoP does not change throughout the year. This helps to counteract this problem by using a heat pump most of the time and a natural gas furnace when the temperature drops below a certain threshold.
However, at this point, the heat pump will use emergency heat to supplement the heat needed to heat your home. If you live in an area where temperatures can drop below freezing, your air source heat pump may be frozen. With the results of the study to come, Winkler's project will create performance maps showing how heat pumps work in different regions of the country where consumers may want them.