Heat pumps outperform fossil fuel heating even in icy conditions, study finds

Heat pumps have been found to be twice as efficient as heating systems that rely on fossil fuels – even when temperatures are very low outside.

A heat pump takes heat at a low temperature from the air or ground and increases it to a higher temperature, before transferring it into homes for central heating and hot water. This heat extraction method means that the efficiency of heat pumps declines in colder temperatures.

However, experiments from researchers at Oxford University and the Regulatory Assistance Project think tank have shown that, even at temperatures as low as -30°C, heat pumps still outperform fossil-fuel-powered systems.

Heat pumps have emerged as a key tool in the global transition towards clean and reliable energy as they can be powered by renewables such as solar and wind, which are carbon neutral. However, concerns have been raised that their declining efficiency in cold weather presents a barrier to their adoption.

The researchers found that even well below 0°C, heat pump efficiency is still significantly higher than fossil fuel and electric resistive heating systems at an appliance level.

In extremely cold climates, where the lowest temperatures approach -30°C, performance data showed that heat pumps can provide heat at efficiencies up to double that of resistive heating.

While air-source heat pumps use electricity to drive a refrigeration cycle that moves heat from a colder source to a warmer destination, ground-source heat pumps have been shown to provide a very high level of efficiency, even during cold weather.

This is because soil temperature does not change significantly between seasons, which results in more predictable efficiency that does not change much over the course of the year. In addition, ground-source heat pumps do not need to expend energy on defrosting, which makes them more suitable for colder climates.

Heat pumps have seen increasing deployment in many countries, and in Europe their use is most concentrated in countries with colder climates. These countries have installed heat pumps for decades and see the highest penetration both in terms of existing fleets and new sales.

According to analysts from the MCS Charitable Foundation, which approves low-carbon certification standards, the UK’s market for heat pumps grew by about 40 per cent in 2022. However, this was from a very low base, with only 1.9 heat pumps installed for every 1,000 households last year, compared with 20 for every 1,000 households in France and nearly 70 in Finland.

The government recently proposed improving access to the grants available to households looking to install a heat pump in an effort to ramp up the UK’s shift towards carbon-neutral heating.

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