Heat Pumps in Old Houses: What UK Homeowners Need to Know in 2026
The short answer
- About £12,700 installed for a typical three bedroom old house (most jobs £11,000 to £15,500), or about £5,200 after the £7,500 grant
- Yes, it works: pre-1919 homes in the government trial did as well as newer ones, and insulating first shrinks the heat pump
- £666 a year on a heat pump tariff against £877 for gas, but £937 on standard electricity
An air source heat pump can be installed in most old houses, including Victorian terraces, Edwardian semis, and stone cottages. A typical three bedroom old house costs about £12,700 installed, the median installers reported under the Boiler Upgrade Scheme in 2025/26 for the 9 kW unit it needs on our model, with most jobs costing £11,000 to £15,500. That covers the whole job as installers recorded it for the grant, cylinder, labour and VAT included; some homes also need larger radiators, and the £7,500 Boiler Upgrade Scheme grant brings it to about £5,200. Insulation is not a condition of the grant, but it cuts the size, cost and running cost of the heat pump. This guide covers insulation priorities, radiator upgrades, costs by house type, planning rules for listed buildings, and how to work out whether a heat pump makes financial sense for your property.
Why old houses need extra preparation
Old houses lose heat faster, so the heat pump must run hotter unless you insulate. Yet in the government trial pre-1919 homes did as well as newer ones, at 2.90 units of heat per unit of electricity.
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Modern homes are built with cavity walls, double glazing, and loft insulation as standard. Old houses, typically anything built before 1930, were not. Solid stone or brick walls, single glazing, draughty floors, and minimal roof insulation mean heat escapes faster. On our model a 3-bedroom semi at the worst insulation the model covers, EPC band E, comes out at 10,989 kWh of annual heat demand, against 6,100 to 8,400 kWh for the same house at bands A to C. That gap is smaller than it feels, and the reason is worth knowing: these figures are metered consumption, and in the NEED data households in the worst EPC bands buy 3 to 5 per cent less gas than band E households in the same size of house, because they ration heating rather than heat the place properly. Size a heat pump on what the building needs, not on what the old system was allowed to deliver.
Heat pumps operate most efficiently at lower flow temperatures: in the Electrification of Heat trial the mean flow temperature of the monitored heat pumps while heating was about 40°C, and efficiency fell as flow temperature rose. In a draughty old house with undersized radiators, the heat pump must run hotter, which lowers its efficiency and raises your electricity bills. The same trial found no significant difference in performance by the age of the house where an installer had judged it suitable: the median for pre-1919 homes was 2.90 units of heat per unit of electricity, against 2.78 across all homes. Good design matters more than age, and insulation makes good design easier.
Use our heat pump cost calculator to estimate running costs based on your property type and insulation level.
Insulation priorities for old houses
Do the loft first, then solid walls, draught-proofing and windows. A loft top-up costs about £600; internal wall insulation costs around £12,000 but cut gas use by a median 17.3%.
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You do not need to insulate everything before fitting a heat pump, but tackling the biggest heat losses first makes the system smaller, cheaper, and more efficient. Here is a sensible order, with the Energy Saving Trust's typical costs and, where it exists, the saving measured in real homes. Measured savings are lower than modelled ones, partly because many homes were under-heated before and take some of the gain as warmth, so treat them as what homes like yours typically saw rather than the most you could save.
1. Loft insulation
The cheapest upgrade. The Energy Saving Trust puts professional loft insulation to 270mm at about £750 from nothing, or £600 as a top-up from 120mm (updated 8 May 2026). Homes that had loft insulation fitted or topped up in 2023 used a median 3.2% less gas the following year (DESNZ NEED impact of measures, June 2026). You can install loft insulation yourself for less, or get it free through the ECO4 scheme if you receive qualifying benefits. Check whether your existing loft insulation still works before adding more.
2. Solid wall insulation
Most old houses have solid walls, not cavity walls. Solid wall insulation is expensive but has the largest measured effect of any single measure: homes that had it in 2023 used a median 17.3% less gas the following year, about 1,857 kWh or £148 at the October 2026 gas price. External wall insulation wraps the building in a layer of insulation and render. Internal wall insulation uses insulated board on the inside face. For a typical three bedroom semi the Energy Saving Trust puts external insulation at around £15,000 and internal at around £12,000 (updated 18 June 2026); a larger detached house costs more.
3. Draught-proofing
Old houses are full of uncontrolled air leaks through floorboards, sash windows, letterboxes, chimneys, and around door frames. The Energy Saving Trust puts professional draught-proofing of a whole house's windows and doors at around £250, the saving from draught-proofing windows, floors and doors at around £55 a year, and the saving from draught-proofing an unused chimney at around £45 a year (updated 20 May 2026). Draught excluder strips are a cheap DIY fix for the most common gaps.
4. Window upgrades
Replacing single glazing with A-rated double glazing costs around £4,800 for a semi-detached house and saves about £85 a year, according to the Energy Saving Trust (updated 20 May 2026). Secondary glazing is cheaper and keeps the original windows, which matters in conservation areas, where replacement windows can need approval.
Insulation first, heat pump second
Every pound you spend reducing heat loss means a smaller heat pump and lower running costs for the next 20 years or more. Use our insulation savings calculator to see figures for your property type.
Choosing the right heat pump for an old house
Air source, sized by a room-by-room heat loss survey. Once insulated, old houses need from 5 kW for a 2-bed terrace to 10 kW for a 4-bed detached, at medians of £11,500 to £13,300.
| Property type | Estimated heat demand | Typical heat pump size | Installed cost, median |
|---|---|---|---|
| 2-bed Victorian terrace (insulated) | 5,355 kWh | 5 kW | £11,500 |
| 3-bed Edwardian semi (insulated) | 8,415 kWh | 7.5 kW | £12,300 |
| 3-bed detached cottage (insulated) | 8,951 kWh | 8 kW | £12,400 |
| 4-bed detached Victorian (insulated) | 11,169 kWh | 10 kW | £13,300 |
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Air source heat pumps are the standard choice for old UK houses. The middle half of the 428 air source heat pumps monitored in the Electrification of Heat trial delivered 2.55 to 3.05 units of heat for each unit of electricity over a year. Ground source systems cost considerably more: the median ground source installation under the Boiler Upgrade Scheme in 2025/26 was £26,200, against £13,021 for air source (DESNZ), and they need garden space for boreholes or ground loops.
For an old house, the critical decision is heat pump sizing. An oversized unit wastes money on installation and switches on and off too often. An undersized unit runs constantly and never reaches comfortable temperatures. A qualified MCS installer will carry out a room-by-room heat loss survey of your property before recommending a unit size. This survey accounts for wall construction, glazing type, insulation levels, room volumes, and your local climate.
Typical sizing for old houses after insulation upgrades, on our model:
The data behind this table
Insulated means EPC band C on our model: loft and wall insulation upgraded, double glazing. The same houses at band E need about 30% more heat and a unit roughly a third larger. Installed cost is the 2025/26 Boiler Upgrade Scheme median for a heat pump of that size, before the grant.
Compare the full cost breakdown by house type in our heat pump costs by house type guide.
Radiator upgrades: do you need them?
Probably, but not always, because a heat pump runs at 35 to 45 degrees instead of 55 to 70. Large original cast iron radiators can often stay, and upgrades done in the job are part of the installed price.
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Probably, but not always. Heat pumps deliver water at 35 to 45 degrees rather than the 55 to 70 degrees from a gas boiler. Your existing radiators may not have enough surface area to heat each room at these lower temperatures.
An MCS installer will calculate the required radiator output for every room. In many old houses, you will need to replace some radiators with larger ones or add extra panels, and when that is done as part of the heat pump job it is part of the installed price rather than an extra. Underfloor heating works well with heat pumps but is disruptive and expensive to retrofit.
Some rooms may already have oversized radiators, especially if the original Victorian or Edwardian units are still in place. Large cast iron radiators have substantial surface area and can work well with a heat pump without replacement.
Cost breakdown for a typical old house
A solid-walled 3-bed Edwardian semi costs around £18,000 in total after the grant. That is the £12,700 median heat pump job less £7,500, plus internal wall insulation, a loft top-up and draught-proofing.
| Item | Cost |
|---|---|
| Air source heat pump installation (9 kW, including cylinder and radiator changes) | £12,700 median; £11,000 to £15,500 |
| BUS grant deduction | -£7,500 |
| Internal solid wall insulation (typical 3-bed semi) | around £12,000 |
| Loft insulation top-up from 120mm | around £600 |
| Professional draught-proofing of windows and doors | around £250 |
| Total after the BUS grant | around £18,000 |
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Here is what a full heat pump retrofit looks like for a 3-bedroom Edwardian semi-detached with solid walls, currently on a gas boiler, at the median costs.
The data behind this table
Heat pump cost from DESNZ Boiler Upgrade Scheme statistics (2025/26 median for a heat pump of that size). Insulation costs from the Energy Saving Trust, updated May and June 2026. Heat pumps and insulation carry 0% VAT until 31 March 2027. BUS grant requires an MCS-certified installer. Apply via GOV.UK.
If you are on a low income and receive certain benefits, you may qualify for ECO4 funding to cover some or all insulation costs until the scheme closes on 31 December 2026, and in England your council may be able to fund insulation and a heat pump through the Warm Homes: Local Grant.
Running costs: heat pump vs gas boiler in an old house
On a heat pump tariff it costs £666 a year against £877 for gas, but £937 on standard electricity. The tariff saving is £211 a year for a 3-bed Edwardian semi.
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At the Ofgem price cap for October to December 2026, electricity costs 26.32p/kWh and gas costs 7.97p/kWh. A heat pump with a seasonal efficiency of 2.78, the median measured in the Electrification of Heat trial, delivers heat at 9.5p per kWh on standard electricity, against 8.9p for gas once boiler efficiency is included, so on a standard tariff it costs slightly more to run. Electricity carries no VAT from October 2026 to March 2027 while gas includes 5%, so if 5% VAT returns to electricity in April 2027 at the same underlying price, the heat pump figures rise by 5%.
Heat pump tariffs offer cheaper electricity at set times. On a heat pump tariff such as Cosy Octopus, about 18.7p/kWh with most heating in the cheap hours, the heat costs about 6.7p per kWh, about 24% below gas. See our full comparison of heat pump electricity tariffs.
For a 3-bed Edwardian semi at 9,900 kWh of annual heat demand, with the loft, draughts and glazing done but the solid walls not yet lined (EPC band D on our model):
| System | Annual heating cost |
|---|---|
| Gas boiler (90% efficiency) | £877 |
| Heat pump (standard tariff) | £937 |
| Heat pump (heat pump tariff) | £666 |
The data behind this table
Based on the Ofgem price cap for October to December 2026. Heat pump seasonal efficiency 2.78. Standing charges excluded. Heat pump tariff at 18.7p/kWh, Cosy Octopus at October 2026 rates with most heating in the cheap hours. On that tariff the heat pump costs £211 a year less than gas.
Read our detailed breakdown of heat pump running costs and use the boiler vs heat pump calculator for your specific property.
Planning permission and listed buildings
Most old houses need no planning permission, but listed buildings always do. Conservation areas limit units facing a road, and every unit must meet the 37 dB noise limit at a neighbour's window.
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Most heat pump installations in England fall under permitted development and do not need planning permission. However, old houses often come with restrictions.
Listed buildings always need planning permission for an air source heat pump, because permitted development does not apply anywhere within the grounds of a listed building (GPDO Class G). Listed building consent is also usually needed for fixings, pipework and holes through the historic fabric, and for internal alterations that affect the building's character. Your local conservation officer will assess the impact.
Conservation areas stop the unit going on a wall or roof that fronts a road, or nearer the road than the house. You may be able to site the heat pump in a rear garden, behind a wall, or use an acoustic enclosure that reduces both noise and visual impact. See our full planning permission guide for details.
Noise decides whether you need planning permission. In England a heat pump is only permitted development if the MCS 020(a) sound calculation shows 37 dB or less at one metre from the nearest habitable room window or door of each neighbour (MCS); Wales moved to the same MCS 020(a) test on 1 June 2026 (MCS). Manufacturers quote sound pressure at one metre of around 40 to 46 dB(A) for units such as the Grant Aerona 290 range, and distance and walls bring that down. Anti-vibration pads reduce transmitted noise further, and our heat pump noise guide has practical reduction tips.
Listed building owners: apply for consent early
Planning permission and listed building consent both take time to decide. Apply before ordering your heat pump to avoid delays. Your installer may have experience with similar properties and can advise on positioning that is more likely to gain approval.
Common concerns with heat pumps in old houses
A correctly designed heat pump keeps an old house warm and does not damage the walls. You will need a hot water cylinder, and the original airing cupboard can often take it.
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Will it keep my house warm enough?
Yes, if the system is correctly designed. A properly sized heat pump with suitable radiators will keep your home at the temperature you set. The difference is that heat pumps deliver steady, consistent warmth rather than the rapid burst of heat from a gas boiler, so the temperature stays more even through the day.
What about hot water?
You will need a hot water cylinder, sized to how much hot water your household uses; the Energy Saving Trust says it will usually fit a cupboard of at least 80 cm by 80 cm (air source heat pumps, updated 16 July 2026). If your old house currently has a combi boiler with no cylinder, you will need to find space for one. Many old houses originally had a cylinder, and the original airing cupboard can often be reused.
Will it damage old walls or structure?
No. The heat pump unit sits outside, connected to the indoor system by pipes that pass through a small hole in an external wall. This is less invasive than fitting a new gas boiler flue. Internal wall insulation does reduce room sizes slightly, by the thickness of the insulation on each treated wall.
Step-by-step: getting a heat pump in your old house
Insulate first, then get three MCS quotes with a full heat loss calculation. The installer claims the £7,500 grant, or £9,000 for oil or LPG homes, and installation takes a few days.
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1. Assess your insulation. Check your current EPC rating and identify the biggest heat loss areas. Use our EPC improvement planner to prioritise upgrades.
2. Insulate first. Tackle loft, walls, and draught-proofing before committing to a heat pump. This reduces the required heat pump size and cost.
3. Get MCS installer quotes. Use the MCS certified installer directory to find local heat pump installers. Get at least three quotes. Each should include a full heat loss calculation.
4. Apply for the BUS grant. Your MCS installer applies on your behalf through GOV.UK, and since April 2026 the installer must take the £7,500 grant off the price they quote you. Until March 2027 it is £9,000 if the house is heated by oil or LPG and has no mains gas connection. The scheme runs to 2030.
5. Check for additional funding. If you are on a low income, check grant eligibility for ECO4 insulation funding before it closes on 31 December 2026, and in England ask your council about the Warm Homes: Local Grant.
6. Install and commission. A typical air source heat pump installation takes a few days. The installer will commission the system, set up your controls, and walk you through operation.
Anti-vibration pads under the outdoor unit and a thermostat set up for steady, low-temperature running make the most of the system.
Frequently asked questions
Can you fit a heat pump in a Victorian house?
Yes. In the Electrification of Heat trial, heat pumps in pre-1919 homes performed as well as those in newer homes where an installer had judged the house suitable. Loft insulation, draught-proofing and larger radiators are the usual first steps, and solid wall insulation helps most but costs most. A typical three bedroom house pays about £5,200 after the £7,500 grant. Use our heat pump calculator to estimate costs for your own house.
Do you need to insulate before installing a heat pump?
You do not legally need to insulate first, and the Boiler Upgrade Scheme does not require it, but it helps. A poorly insulated old house needs a larger heat pump, which costs more to install and to run. Our insulation savings calculator shows you the return on insulating first.
Will a heat pump heat an old stone house?
Yes, if the system is designed for it. Stone and solid brick walls lose more heat than modern cavity walls, so the heat loss calculation must use the real wall construction, and you may need larger radiators or wall insulation. A well-designed system with suitable radiators will heat a stone house effectively.
How much does a heat pump cost for an old house in the UK?
About £12,700 installed for a typical three bedroom old house, the 2025/26 Boiler Upgrade Scheme median for the 9 kW heat pump it needs on our model, with most jobs costing £11,000 to £15,500. That covers the whole job as installers recorded it for the grant, cylinder, labour and VAT included; some homes also need larger radiators. The £7,500 BUS grant reduces it to about £5,200.
Do I need planning permission for a heat pump on a listed building?
Yes. Permitted development does not apply to an air source heat pump anywhere within the grounds of a listed building, so it always needs planning permission, and it will usually need listed building consent for the fixings, pipework and holes through the historic fabric. Read our planning permission guide for the full process.
Data sources
Costs come from the DESNZ Boiler Upgrade Scheme statistics, August 2026. Efficiency comes from the Electrification of Heat trial, insulation costs from the Energy Saving Trust and prices from the Ofgem price cap.
Show every source
Installed prices from DESNZ Boiler Upgrade Scheme statistics, August 2026 release (Table A1.3A, median cost by capacity and technology, 2025/26). Heat pump efficiency and flow temperatures from the Electrification of Heat Demonstration Project performance report (Energy Systems Catapult for DESNZ, December 2024). Heat demand from our heating model, built on the DESNZ National Energy Efficiency Data-Framework. Measured insulation savings from NEED impact of measures (June 2026). Insulation costs from the Energy Saving Trust (loft, solid wall, draught-proofing, windows). Energy prices from Ofgem price cap, October to December 2026. Heat pump tariff from Cosy Octopus at October 2026 rates, as costed in our tariff guide. BUS grant details from GOV.UK. Planning rules from legislation.gov.uk, the Planning Portal and MCS.