Will a heat pump work in my old British home?

Can a heat pump really heat a Victorian or 1930s house?

Plenty of people assume heat pumps are for new-builds. The evidence says otherwise. The Electrification of Heat demonstration project, funded by the government, put 742 heat pumps into a broad spectrum of British housing types and ages. Its summary concludes that heat pumps can be successfully installed in all the types of property tested, and its performance analysis found that home age did not have a statistically significant impact on the measured efficiency.

This matters because Britain's housing is old. The English Housing Survey for 2024 found that 20% of owner occupied homes in England were built before 1919, and 32% of privately rented homes. If heat pumps only worked in modern houses, a large share of the country would be ruled out. They are not.

What age does change is the likely starting point: how the walls were built, how much insulation there is, how draughty the windows and floors are. Those things set your heat loss, and heat loss sets everything else.

Why does heat loss matter more than the age of the house?

Heat loss is the rate at which your home leaks heat on a cold day, measured in watts or kilowatts. Under the MCS design standard, an installer calculates it room by room at the design outdoor temperature for your area (for London, -1.7°C or -3.0°C depending on the method), then chooses a heat pump that can supply at least 100% of it.

• Higher heat loss means a bigger heat pump, which costs more to buy.
• It also means each room needs more heat from its radiators. Either the radiators get bigger, or the water running through them gets hotter.
• Hotter water means lower efficiency. The Electrification of Heat analysis found that systems with lower average flow temperatures (the temperature of the water sent to the radiators) achieved higher efficiency.

So an 1890s terrace with a new loft, draught-proofed sash windows and a sealed suspended floor can be a better heat pump home than a leaky 1970s house nobody has touched. Age is a clue, not a verdict.

What should be done first, the insulation or the heat pump?

Fabric first, in most older homes, for a practical reason: once a heat pump is sized for a leaky house, insulating later leaves you with a unit that is bigger than it needs to be. Here is how the sequence usually looks by era. Treat it as a starting point for a survey, not a rule.

Not sure what your walls are? Our guide to cavity or solid walls shows how to tell, and your EPC, if you have one, lists the wall type. The EPC explainer helps you read it.

Will you need new radiators?

Probably some, rarely all. Older homes usually have radiators sized for a gas boiler sending much hotter water around the house. A heat pump is most efficient with cooler water, so a room whose radiator was only just big enough at boiler temperatures may need a larger one, or a second one.

• The room-by-room heat loss calculation tells you exactly which rooms fall short at the design flow temperature.
• Rooms with the biggest heat loss relative to wall space (bay windows, extensions with glazed roofs, rooms with two external walls) are usually the ones that change.
• Existing pipework needs checking too: pipes that are too narrow for the flow rate the heat pump needs may have to be changed in places.
• Underfloor heating suits heat pumps well where floors are being lifted anyway. See our underfloor heating service.

High temperature heat pumps exist for homes where radiators genuinely cannot be enlarged, such as some listed interiors. The MCS design standard says they should be avoided unless a home needs water hotter than 55°C. Interestingly, the Electrification of Heat trial found high temperature models did not perform worse in practice, which the report puts down to better refrigerants and weather compensation keeping them at lower temperatures most of the time.

Do you need planning permission for a heat pump on an older house?

In England, most air source heat pumps on houses are permitted development, so no planning application is needed, provided the unit complies with MCS planning standards. The rules changed on 29 May 2025.

• The old rule that the unit had to be at least 1 metre from your boundary has been removed. That helps terraces and small gardens a great deal.
• The outdoor unit (including any housing) can be up to 1.5 cubic metres on a house, up from 0.6.
• A detached house can have up to two units; other houses one.
• The unit must meet the MCS 020(a) sound calculation limit of 37 dB at the neighbours' assessment positions.
• It cannot go on a pitched roof.
• Listed buildings are excluded from permitted development, so you need consent.
• In a conservation area or World Heritage Site, the unit cannot go on a wall or roof facing a highway, or closer to a highway than the house.

Wales and Scotland have their own rules. Our planning permission guide covers the detail.

Where does the outdoor unit go on a terrace with a small garden?

With the boundary rule gone, the main constraints are noise, airflow and access. A side return, a rear wall or a flat roof over a back extension (kept at least 1 metre from the roof edge under permitted development) are common spots. The MCS 020(a) calculation accounts for distance to the nearest neighbour's window, the number of reflecting walls around the unit, and any barrier in between, so a tight courtyard with walls on three sides needs more care than an open garden.

Inside, the other space question in an older house is the hot water cylinder. If you had a combi boiler and no airing cupboard, finding a home for the cylinder is often a bigger design decision than the outdoor unit.

When should an older home not get a heat pump yet?

We would rather lose the job than fit a heat pump that disappoints. These are the situations where waiting, or a different plan, is the honest advice.

• Heat loss is very high and you cannot do fabric work yet. A high-efficiency boiler now and a heat pump after insulation can be the better sequence. Our boilers and central heating service covers that route.
• Solid walls with damp problems that have not been diagnosed. Fix the moisture first.
• A listed building where consent for the unit or larger radiators is unlikely.
• No workable space for a cylinder, and no appetite to create one.
• A quote that does not include a room-by-room heat loss calculation. Do not proceed on a guess.

If you want help ordering the work for your own house, the retrofit planner turns your answers into a step-by-step plan, and a survey from Smart Energie puts real heat loss figures against it.

Common questions