Air-source heat pumps

Air-source heat pumps are increasingly familiar in our homes – but they can also provide an effective low-carbon heating solution for churches.

Rather than creating heat by burning fuel, a heat pump captures heat already present in the outside air and transfers it into the building. This means it can provide significantly more heat energy than the electrical energy it consumes.

For the right building, with the right pattern of use, this can offer an efficient way of moving away from fossil-fuel heating.

What is an air-source heat pump

An air-source heat pump works a little like a refrigerator in reverse.

An external unit extracts low-level heat from the outside air. Electricity powers the compressor and other components which increase the temperature of that heat before it is transferred into the church.

There are two main ways this can be done:

• Air-to-water heat pumps – heat water for radiators, fan convectors or underfloor heating. They work best at lower temperatures than traditional boilers, so existing radiators or pipework may sometimes need upgrading.
• Air-to-air heat pumps – provide warm air directly through internal fan units. They can heat spaces quickly, avoid the need for a wet heating system and can often be zoned so only the areas being used are heated.

Some systems can also provide cooling during warmer weather.

Why consider a heat pump

• Works well in frequently used churches – heat pumps can be particularly effective where a church is used regularly and there is a need to heat a substantial part of the building.
• Can form part of a hybrid system – a heat pump can sometimes be combined with an existing gas boiler, allowing the heat pump to meet much of the heating demand while the boiler provides additional heat when needed. This can offer a practical stepping stone away from fossil fuels.
• Pairs well with renewable energy – heat pumps can work particularly well alongside technologies such as solar PV, helping churches generate some of the electricity used for heating.
• Heating and cooling – air-to-air systems can often provide both heating and cooling, offering additional flexibility for heavily used churches, halls and meeting spaces.

What should we think about?

Air-source heat pumps are already being used in churches ranging from small rural parish churches to major historic buildings. Both air-to-air and air-to-water approaches have been successfully applied, often alongside improvements to the building fabric, solar PV or changes to the way the church is heated. We will be sharing some stories of churches in our diocese that are using air-source heat pumps soon.

However, heat pumps are not automatically the right answer for every church. The success of a heat-pump project depends heavily on good design and understanding the building properly before selecting equipment.

For significant heating projects, we suggest considering the building and its needs first. Start with an options appraisal – not a heat-pump quote. A contractor can tell you how they would install a heat pump. That is not necessarily the same as establishing whether a heat pump is the best way to heat your church.

An options appraisal can look at:

• how the building is used
• heat-loss calculations
• the existing heating system
• fabric improvements
• electrical supply and demand
• different heating technologies
• likely capital and operating costs
• heritage implications
• controls and zoning.

That gives the PCC a stronger basis for making a decision before moving into detailed specification and installation.

Thinking about a heat pump?

Speak to the Church Buildings Adviser or Net Zero Project Lead before commissioning a system.

We can help you understand whether a heat pump may be suitable, what investigations are needed, how to approach an options appraisal and specification, and what we have learnt from other projects.