Every number here traces back to a source
The evidence about British homes is already public. It is just scattered across registers that were never designed to answer a homeowner's question. This is what we use, how we handle it, and what we do when it runs out.
Public sources only
Registers and official statistics anyone can go and read for themselves.
Dated, not undated
Every figure will carry the date we last checked it against its source.
Labelled when uncertain
An estimate says it is an estimate, in the place you read it.
Open about the gaps
Where the data does not reach, we say so instead of filling it in.
Sources
What the site is built on
Six sets of public data, each answering a different part of the same question: what is this house, what would work on it, who can do it and what should it cost.
- Open Government Licence
EPC registers
Published separately by each UK nation
Energy certificates address by address: rating and score, floor area, wall and roof construction, glazing, heating type and the measures a surveyor recommended. This is the backbone — it is how a postcode becomes a property rather than a guess.
- Open Government Licence
Census and ONS statistics
ONS, National Records of Scotland, NISRA
How the homes in an area were built, when, who owns them and what heats them. It fills in the picture where a certificate is missing, and it is what lets us say what is normal for a street rather than for the country.
- Open Government Licence
Scheme rules
Ofgem, GOV.UK and the devolved governments
Grant amounts, qualifying criteria, opening and closing dates for every scheme on the grants page. These change often, so each one is stored with the date it was read rather than treated as permanent.
- Open Government Licence
Planning and heritage records
Local authorities and the national heritage bodies
Conservation areas and listed buildings, which change what you are allowed to fit and what it costs. A rule that bans external wall insulation matters more than any price we could quote.
- Published research
Monitored performance
UK field trials and demonstration projects
Measured efficiency from real homes over real winters, rather than the figure on the box. It is the difference between what a heat pump can do in a lab and what one did in a Yorkshire semi.
Handling
How a public file becomes an answer
Four steps, and the first one matters most: we keep the source exactly as it was published, so any figure can be traced back to the file it came from.
Land it raw
Each release is loaded exactly as published into a staging area and left alone. Nothing is edited on the way in, so we can always go back to what the source actually said.
Clean it
Addresses matched, duplicate certificates resolved to the most recent, units normalised, obvious errors flagged rather than quietly corrected.
Join it to a question
Property to area, area to scheme, scheme to installer. The joins are where the answers come from, and where the mistakes would come from too.
Publish with a date
Every figure that reaches a page carries its source and the date it was last checked, so you can tell a current number from an old one.
Loaded today
The data behind the figures you can read now
22 datasets are published to the site. Each figure drawn from one says so where it appears; anything else is labelled illustrative.
| Dataset | Publisher | Covers | Data as at |
|---|---|---|---|
| UK geography codesWhere an authority was split, its history follows the successor with the same name, which is right for minor boundary changes and approximate otherwise. | ONS Open Geography Portal | UK | 1 June 2026 |
| Council boundariesUltra-generalised boundaries (BUC): right for which council a place is in, not for anything drawn at street level. | ONS Open Geography Portal | UK | 1 May 2026 |
| ONS Postcode DirectoryContains OS data © Crown copyright and database right, Royal Mail data © Royal Mail copyright and database right, and National Statistics data © Crown copyright and database right. | Office for National Statistics | UK | 31 August 2026 |
| Renewable electricity by local authorityCounts every site, from home roofs to solar farms; there's no split for homes. | Department for Energy Security and Net Zero | UK | 31 December 2024 |
| Solar photovoltaics deploymentRegional figures only; there's no local authority breakdown in this table. | Department for Energy Security and Net Zero | UK | 31 July 2026 |
| Energy efficiency of housingOnly dwellings with an EPC are counted, and a home gets one when it's built, sold or let, so shares describe certified homes rather than all homes. | Office for National Statistics, via Nomis | England, Wales | 31 December 2024 |
| EPC register, domestic certificatesOnly homes that have been built, sold or let since certificates began have one, so this describes certified homes, not all homes. | Ministry of Housing, Communities and Local Government | England, Wales | 9 September 2026 |
| Scottish EPC Register (domestic)Address and postcode fields carry Royal Mail terms; every other field is Open Government Licence v3.0. | Scottish Government | Scotland | 31 March 2026 |
| Northern Ireland EPC registerNo bulk download exists; each refresh needs another request to the Department. | Department of Finance (Northern Ireland) | Northern Ireland | 1 April 2026 |
| Warm Homes: Local Grant statisticsMost allocations go to projects run by several councils together, so a council's figure is usually its project's, not its own. | Department for Energy Security and Net Zero | England | 31 July 2026 |
| Boiler Upgrade Scheme statisticsCounts only installations paid a Boiler Upgrade Scheme grant; heat pumps paid for without one aren't here. | Department for Energy Security and Net Zero | England, Wales | 30 June 2026 |
| Energy price cap unit rates and standing chargesNorthern Ireland isn't covered by the price cap. | Ofgem | England, Wales, Scotland | 1 October 2026 |
| Octopus Energy tariffsOne supplier: other suppliers' products on the site are still illustrative. | Octopus Energy | England, Wales, Scotland | 17 September 2026 |
| Sunshine, rain and temperature, station averagesA few dozen long-running stations, not a map: a place far from a station isn't well described by it. | Met Office | UK | 31 August 2026 |
| Sunshine hours, gridded averages (HadUK-Grid)A council's figure is the plain average of the 1 km grid squares whose centres fall in it, so uplands and coast count as much as towns. | Met Office | UK | 31 December 2020 |
| Solar generation by council (PVGIS)A modelled array: crystalline silicon, 14% system losses, a 35° pitch, no shading beyond the terrain. A real roof's pitch, shade and panels move the figure. | European Commission Joint Research Centre | UK | 31 December 2023 |
| Planning applications in EnglandPermitted development isn't counted: most domestic solar and many heat pumps never need an application, so an approval rate here describes the minority of jobs that did. | Ministry of Housing, Communities and Local Government | England | 31 March 2026 |
| Planning Data platform: conservation areasCoverage follows adoption of the data standard, so an authority reporting none has usually published none rather than having none. | Ministry of Housing, Communities and Local Government | England | 20 September 2026 |
| Development management quarterly survey (Wales)This is a performance survey: it counts what was decided and how long it took, but not how many were approved. Welsh approval rates need the StatsWales planning decisions dataset. | Welsh Government | Wales | 31 March 2026 |
| Planning applications statistics (Scotland)Permitted development isn't counted, and Scotland's rights are wider than England's, so even less work reaches an application here. | Scottish Government | Scotland | 31 March 2025 |
| Northern Ireland planning statisticsEleven councils cover the whole of Northern Ireland, so each figure hides a lot of local variation. | Department for Infrastructure (Northern Ireland) | Northern Ireland | 31 December 2025 |
| Electricity network operator areasWhich licence area a council is in comes from sampling points across it every kilometre; a council on a boundary is split by the share of its land in each. | NESO | England, Wales, Scotland | 3 May 2024 |
Honesty
What we do when we don't know
Large parts of this site are ahead of the data behind them. Rather than hold the guides back or quietly invent a figure, the placeholder numbers are labelled wherever they appear:
Illustrative. Placeholder figures to show what this page will hold. Real ranges arrive with the quote and performance data behind them.
When a label disappears, it is because the source behind that number is loaded and dated. Until then, treat it as the shape of an answer rather than the answer.
What we won't do
- Scrape review sites and present them as evidence
- Sell or share personal data to fund the site
- Publish an estimate without saying that it is one
- Give you a national average and call it your answer
Energy certificate data is already public at address level. We show what is published, and nothing we have collected about you.
Think a figure is wrong?
Tell us which page and which number. If the source disagrees with us, we change the page.
Contains public sector information licensed under the Open Government Licence v3.0. Source data remains the property of the bodies that publish it.