Buying an older or off-gas home: the energy questions to ask
The short answer
- £2,216 a year to heat a band D 3 bed semi by oil, against £1,885 on mains gas
- 79% of homes built before 1919 have uninsulated solid walls; insulating them costs about £12,000 to £15,000
- Free checks on GOV.UK for flood risk and coal mining; a mining report starts at £27 plus VAT
- Level 3 survey for a large, older, run-down or altered home, says RICS
An older home or one off the gas grid can cost far more to run than its asking price suggests: a band D 3 bed semi heated by oil costs about £2,216 a year, against £1,885 on mains gas. These 9 questions cover the heating, the walls and windows, planning restrictions, what the listing must tell you, flood and mining checks, and which survey to book.
1. How is it heated, and is it on the gas grid?
About £2,216 a year heated by oil, against £1,885 on mains gas, for a band D 3 bed semi. Ask the age of the boiler and tank and for recent fuel receipts.
| Heating | A year | A month |
|---|---|---|
| Mains gas boiler | £1,885 | £157 |
| Oil boiler | £2,216 | £185 |
| LPG boiler | £2,006 | £167 |
| Electric heating, standard rate | £3,506 | £292 |
Read the detail
A band D 3 bed semi costs about £2,216 a year heated by oil and £2,006 by LPG, against £1,885 on mains gas, at today's prices. Ask how old the boiler and tank are, and what the last year's fuel cost.
Priced at the Ofgem price cap for October to December 2026, paying by direct debit: gas 7.97p and electricity 26.32p per kWh, with standing charges of £108.33 for gas and £200.13 for electricity a year. Heating oil is 11.3p per kWh, the BoilerJuice UK average on 25 September 2026, and LPG 9.5p, our assumption for a typical bulk contract. Oil prices move from month to month, so ask the seller for recent delivery receipts.
The heating is part of the material information an estate agent should give you (see question 6). Off the gas grid, the long term alternative is usually a heat pump: the Boiler Upgrade Scheme gives £9,000 towards one where it replaces oil or LPG, against £7,500 otherwise. Our heat pump calculator and heat pumps in old houses guide cover what that would cost.
2. Are the walls solid or cavity, and insulated?
79% of pre-1919 homes have uninsulated solid walls. Insulating them costs about £12,000 inside or £15,000 outside.
| Feature | Built before 1919 | All homes |
|---|---|---|
| Solid walls, not insulated | 79% | 24% |
| Double glazing throughout | 69% | 89% |
| Heated by oil | 7% | 3% |
| EPC band E, F or G | 24% | 9% |
Read the detail
79% of homes in England built before 1919 have solid walls with no insulation, against 24% of all homes. Insulating solid walls costs about £12,000 inside or £15,000 outside, and cuts gas use by a measured 17%.
English Housing Survey 2024 live tables, MHCLG, England.
The EPC records the wall type, and so should the listing: the property's construction is part of the material information. Solid walls are typical of homes built before about the 1930s; cavity walls of homes built after. An unfilled cavity is the cheap fix, about £2,200 for a semi. A solid wall is the dear one, which is why many older homes sit in band D or E. See solid wall insulation cost and EPC ratings for Victorian houses.
3. Is it single glazed?
Replacing single glazing costs about £4,800 for a semi and saves about £85 a year, so judge windows on comfort and condition.
Read the detail
69% of homes built before 1919 have double glazing throughout, against 89% of all homes. Replacing single glazing costs about £4,800 for a semi and saves about £85 a year, according to the Energy Saving Trust.
That payback is long, so judge windows on comfort and condition: rotten sashes need work whatever the bill. Secondary glazing keeps the original windows, which matters in a conservation area or on a listed building, where replacement windows can need approval. Draught-proofing is the cheap first step; our draught-proofing guide covers it.
4. Is it listed or in a conservation area?
Listed homes need consent for work that affects their character, which can include insulation, windows and a heat pump.
Read the detail
A listed building needs listed building consent for any work that would affect its character, under the Planning (Listed Buildings and Conservation Areas) Act 1990, and that can include insulation, new windows and a heat pump. Carrying out such work without consent is a criminal offence.
In England, permitted development for an air source heat pump does not apply to a listed building or anything within its grounds, so it needs planning permission. In a conservation area permitted development still applies, but the unit cannot go on a wall or roof that fronts a road. External wall insulation in a conservation area may need planning permission too, which is why internal insulation is often the option chosen there.
Ask the agent and check the council's records before you offer: listed status and conservation areas are among the restrictions an agent should disclose (question 6). Our heat pump planning permission guide has the full rules for each nation.
5. What does the EPC say, and how old is it?
Read the whole certificate, free on the government register. It rates each part of the home and lists recommendations, and it lasts ten years.
Read the detail
Read the full certificate, not just the band. It lists the walls, roof, windows, heating and lighting, each with its own rating, and a set of recommendations with indicative costs.
Every EPC lodged in England and Wales is free to read on the government register, searchable by postcode. A certificate lasts ten years, so an old one may not show work done since, and the seller must have commissioned one before the home was marketed. Put the band into our home buyer energy check for the bill now and the cost to reach band C, and see what the recommendations cost.
6. What does the listing's material information say?
Agents must not leave out material information, which includes the heating and utilities. The duty sits in the Digital Markets, Competition and Consumers Act 2024.
Read the detail
Estate agents must not leave out information a buyer needs to make a decision. Since 6 April 2025 that duty sits in the Digital Markets, Competition and Consumers Act 2024, enforced by the Competition and Markets Authority.
National Trading Standards' guidance, published on 30 November 2023, split material information into three parts. Part B covered what should be given for every property: the property type and construction, the number and types of rooms, and the utilities, including electricity, water, sewerage, heating, broadband and mobile signal, plus parking. Part C covered what applies to some homes, including restrictions such as conservation areas and listed status, flood risk, coastal erosion and whether the home is in a coalfield or mining area.
Propertymark reported on 9 May 2025 that the guidance had been withdrawn from official channels as the new Act took over, but that the duty to provide material information remains. If a listing does not say how the home is heated, ask before you view.
7. Is it at risk of flooding?
Check the address on the GOV.UK long term flood risk service, which covers England. It shows the risk for an area, not a single house.
Read the detail
Check the address on the government's long term flood risk service. It covers England, and shows the long term risk from rivers and the sea, surface water, reservoirs and, where data is available, groundwater.
It gives the risk for an area, not for a single house, and does not cover blocked drains or burst pipes. Wales, Scotland and Northern Ireland have their own services, which the GOV.UK page links to. Flood risk is also part of the material information an agent should disclose (question 6), and it matters for insulation: our cavity wall insulation guide explains why some homes at risk of flooding are not suitable for it.
8. Is it in a former coal mining area?
Search free on GOV.UK. If the home is in a former coal mining area, a mining report starts at £27 plus VAT.
Read the detail
Search the address free on GOV.UK's coal mining check, run by the Mining Remediation Authority. If the home is in a former coal mining area, the search tells you whether you need a mining report, which starts at £27 plus VAT.
A report covers mine entries within 20 metres of the property's boundaries, gas emissions from coal mines, other coal mining hazards reported in the area and plans for future coal mining. It usually arrives by email within 24 to 48 hours. Your conveyancer will often order one as part of the searches, so ask before paying twice.
9. Which survey: Level 2 or Level 3?
Level 3 for a large, older, run-down or altered home, or where you plan major works. RICS surveys do not include an energy assessment.
Read the detail
RICS describes its Level 3 survey, previously called a Building Survey, as the one for a large, older or run-down property, a building that is unusual or altered, or where you plan major works. Level 2 suits conventional homes in reasonable condition.
An older home that needs insulating or a new heating system is usually a Level 3 case, because the surveyor's advice on damp, ventilation and the condition of walls and roof decides what insulation is safe to fit. RICS notes that its home surveys do not include an energy assessment, so read the survey alongside the EPC, not instead of it. In Scotland the seller's Home Report includes an energy report and an EPC.
Frequently asked questions
What should I ask before buying a house with oil heating?
How old the boiler and tank are, what the last year of deliveries cost, and whether the tank meets current rules. A band D 3 bed semi costs about £2,216 a year heated by oil against £1,885 on gas, and oil prices move.
Is it harder to insulate an older house?
Often, because most homes built before 1919 have solid walls with no cavity to fill. Solid wall insulation costs about £12,000 inside or £15,000 outside, against about £2,200 to fill a cavity in a semi.
Does an estate agent have to tell me how a house is heated?
The heating is part of the material information agents are expected to give, and leaving out material information is an unfair commercial practice under the Digital Markets, Competition and Consumers Act 2024. If a listing does not say, ask.
Do I need a Level 3 survey for an old house?
RICS recommends Level 3 for large, older or run-down properties, unusual or altered buildings, or where you plan major works. Its surveys do not include an energy assessment, so read the EPC as well.
How do I check flood risk before buying?
Use the long term flood risk service on GOV.UK for an address in England. It shows the risk from rivers and the sea, surface water, reservoirs and, where data exists, groundwater. Wales, Scotland and Northern Ireland have their own services.
Data sources
GOV.UK, RICS, National Trading Standards and Propertymark for the checks and rules; our bill model for the running costs.
Show every source
- GOV.UK, check the long term flood risk for an area in England.
- GOV.UK and the Mining Remediation Authority, find out if a property is affected by coal mining.
- RICS, house surveys: the costs, types and benefits of an RICS Home Survey.
- National Trading Standards, full material information guidance published, 30 November 2023; Propertymark, material information guidance withdrawn as the Digital Markets, Competition and Consumers Act takes over, 9 May 2025.
- Planning (Listed Buildings and Conservation Areas) Act 1990; permitted development rules as set out in our heat pump planning guide.
- Ministry of Housing, Communities and Local Government, English Housing Survey 2024 live tables on energy performance.
- DESNZ National Energy Efficiency Data-Framework 2026 and the Ofgem price cap for October to December 2026, through our bill model; Energy Saving Trust insulation and glazing costs.