Can Air Source Heat Pumps Cool

Air source heat pumps have become one of the most popular renewable heating solutions in the UK, thanks to their ability to use electricity to extract heat from the outside air and transfer it indoors. Many homeowners understand them as a low carbon alternative to traditional gas or oil boilers, but an increasing number of people are now asking whether these systems can also provide cooling. With rising summer temperatures, the idea of having a single system that both heats and cools is very appealing. The answer depends on the type of heat pump you have and how it has been installed.

How air source heat pumps normally work

In heating mode, an air source heat pump draws heat from the outside air, even in winter, and transfers it into your home using a refrigerant cycle. The heat is then distributed through radiators, underfloor heating, or a hot water system. This process is highly efficient, often producing three or more units of heat for every unit of electricity consumed. However, the way the system is designed determines whether it can be reversed to provide cooling.

The difference between heating-only and reversible systems

Not all air source heat pumps are capable of cooling. Some models are designed purely to provide heating and hot water, so they cannot operate in reverse. Others, known as reversible heat pumps, can change direction in the refrigerant cycle. Instead of transferring heat into your home, they can move heat out, effectively working like an air conditioning unit. This function is sometimes called active cooling. If your heat pump is reversible, you will be able to use it for both heating in winter and cooling in summer.

How cooling with a heat pump feels

When set to cooling mode, a reversible air source heat pump lowers the temperature of indoor spaces by absorbing heat from inside and releasing it outdoors. The effect is very similar to air conditioning, although the way the cool air is delivered can feel different depending on your system. For example, underfloor cooling produces a gentle, even reduction in temperature, while fan coil units or air handling systems may provide a more noticeable flow of cool air. Radiators designed for heating are generally not effective for cooling, which is why the type of heat distribution in your home is an important factor.

Energy efficiency when cooling

Heat pumps are still efficient when used for cooling, but it is important to recognise that electricity use will increase during hot weather. The coefficient of performance (COP) that applies to heating is replaced by the energy efficiency ratio (EER) in cooling mode. Well-designed systems can achieve good efficiency, but cooling will always add to your electricity bill. In the UK climate, where very hot summers are relatively short, the extra running costs are usually much lower than in countries with long heatwaves. Nevertheless, proper insulation and shading can help reduce the demand for cooling and keep costs down.

Suitability of existing heating systems

If your home uses traditional radiators, it is unlikely that you will be able to use your air source heat pump for cooling. Radiators are designed to emit heat, not absorb it, and so they do not work well in reverse. Homes with underfloor heating or fan coil units are much better suited to reversible systems. If you are considering installing a new heat pump and want cooling as an option, it is worth discussing this with your installer so that the system can be designed to suit both heating and cooling requirements.

Passive cooling options

Some ground source heat pumps can provide passive cooling, where the cool temperature of the ground is used to lower indoor temperatures without running the compressor. Air source heat pumps do not usually offer this option, as they rely on outdoor air rather than stable ground temperatures. That said, certain advanced systems may provide low energy cooling features, although these are less common in the UK market.

Environmental considerations

Cooling with a heat pump is still more environmentally friendly than running a traditional air conditioning unit powered by older technology. Because a single system is used for both heating and cooling, it reduces the need for additional appliances and lowers overall carbon impact. As the UK electricity grid becomes greener, using a reversible heat pump for cooling is likely to become an increasingly sustainable option.

Practical examples in the UK

In newer, well-insulated homes built with underfloor heating, reversible air source heat pumps are already being used to keep rooms cool in the summer months. This can be particularly beneficial in properties with large windows or modern open-plan layouts that are prone to overheating. In contrast, older homes with limited insulation and small radiators may not be well suited to cooling, meaning the heat pump should be considered for heating only. Each property therefore requires individual assessment to determine whether cooling is a realistic option.

Conclusion

Air source heat pumps can provide cooling, but only if they are designed as reversible systems and installed with the right heat distribution methods. Homes with underfloor heating or fan coil units are the most compatible, while radiator-based systems are less effective for cooling. Efficiency remains strong, although electricity use will rise during hot weather. For UK homeowners, the ability to both heat and cool with one renewable system can be an attractive option, particularly as summers become warmer. If you are planning a new installation, it is worth discussing reversible models with your installer to futureproof your home and ensure year-round comfort.