Germany’s government has signaled it will slow parts of its renewables push and revise a key heating law amid pressure from fossil‑fuel interests and public doubts about alternatives like heat pumps. Although many new buildings already include heat pumps, a lot of Germans remain unsure whether they work as well as traditional gas, oil or coal systems.
Experience from colder countries shows those doubts are misplaced. Heat pumps have been standard in places such as Norway and Finland for years, where winter temperatures frequently drop below −20 °C (−4 °F) for extended periods.
Why cold isn’t a fatal problem for heat pumps
Heat pumps rely on refrigeration technology similar to refrigerators and air conditioners. The refrigerants used in their heat exchangers boil at temperatures well below −40 °C, so even very cold air still contains heat that a pump can extract and move indoors. Modern air‑source heat pumps in Scandinavia and Arctic regions operate effectively down to around −25 °C. When temperatures fall further, a small electric resistance heater can supplement the system to maintain indoor comfort.
Ground‑source (geothermal) heat pumps are even less affected by winter extremes because they draw heat from soil or groundwater, where temperatures remain much steadier. Deep ground loops can access heat from layers a few hundred meters down, where temperatures often stay near 10 °C even when the surface is far below freezing.
Efficiency in cold weather
Because heat pumps move ambient heat rather than producing it by combustion, most of the energy they deliver is taken from the environment. In Scandinavian installations, roughly two‑thirds of the delivered heat comes from the surroundings, with the remainder supplied by the compressor motor. On an annual basis a typical heat pump can deliver about 3 kWh of heat for every 1 kWh of electricity consumed — roughly 300% efficiency. By contrast, gas boilers are usually under 100% efficient, and older models often operate below 80%.
Performance falls as outdoor temperatures drop, but it remains competitive. At about 12 °C a modern heat pump can transfer as much as 10 kWh of heat per 1 kWh of electricity (COP ≈ 10). At −20 °C, a 2023 study in Joule found modern units in Finland delivered about 2 kWh per 1 kWh of electricity (COP ≈ 2); at −30 °C the COP was between 1 and 2. Field trials of cold‑climate heat pumps in Alaska showed similar figures: roughly 2 kWh per 1 kWh at −25 °C and about 1.8 at −35 °C. Even with those reductions, heat pumps remain more efficient than burning fossil fuels for the same heat output.
Adoption in cold countries
Heat pumps dominate residential heating in Norway, Sweden and Finland despite their long, cold winters. Around 66% of Norwegian households use heat pumps, 55% of Finnish homes do, and slightly more than half of Swedish households rely on them. For new construction in all three countries, heat pumps account for over 90% of installed heating systems. Cities and district‑heating networks are also deploying very large heat pumps to replace polluting fuels: for example, Helsinki plans the world’s largest air‑source heat pump, expected by the end of 2026 to supply heat to 30,000 homes, delivering up to 33,000 kW and operating efficiently down to −20 °C, avoiding about 26,000 tons of CO2 emissions.
Choosing and installing a heat pump
Heat pumps can heat or cool most buildings, and many households see substantial savings. In Germany’s relatively mild climate, heat‑pump owners typically save at least 30% on heating bills; in Sweden savings often exceed 50%. Norway banned heating oil in 2020 as part of efforts to cut greenhouse gases.
Before switching, consult a qualified installer. Good insulation and building sealing improve comfort and cut operating costs. Air‑source units are generally cheaper to buy and install than ground‑source systems because they are more widely manufactured and avoid the drilling needed for ground loops, but the best choice depends on local conditions and energy prices.
Bottom line: heat pumps are proven technology that works in very cold climates. With proper design, insulation and the right system for a site, they provide an efficient, low‑carbon way to heat buildings even in freezing weather.
Originally written in German.