An EPC estimates a home's annual heating, hot water and lighting costs — but at the energy prices of the year it was produced, so an older one can be badly out. Read the kWh per m² per year figure, re-price it at today's rates, and treat the result as a comparison rather than a bill.
Every EPC carries an estimate of what the home costs to run — heating, hot water and lighting, quoted per year. It is the one running-cost estimate you can read before you own the house — though twelve months of the seller's own bills, if they will share them, beat any model — and it comes with a catch: those costs are modelled at the energy prices of the certificate's own year, and a certificate stays valid for ten years from lodgement (position as of August 2026).
Be clear about what this guide is. It is an article, not a bill calculator, and it cannot tell you what a particular house will cost you. It can show you how to read the figures the certificate already holds, how to re-price them, and what to do with the answer. If you want a number for a specific property rather than the method, the free EPC checker re-prices that certificate's own estimates at rates stated as of early 2026 — modelled figures, not a prediction of your bills.
This guide covers domestic certificates in England & Wales; Scotland and Northern Ireland are outside its scope.
What the certificate actually estimates
An EPC's running-cost figures cover three uses only: space heating, hot water and lighting. They are modelled from the building — floor area, walls, roof, glazing, heating system and fuel — under a standard set of assumptions, not measured from anyone's meter.
That leaves a lot out. Cooking, appliances and anything you plug in are absent, as are standing charges. Your bill will run higher than the certificate's total, and that gap is not evidence the certificate is wrong.
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Why the pounds are the least reliable figure on the page
A certificate lodged nine years ago quotes running costs at the prices of nine years ago, and nothing on the register updates them. Prices have since moved sharply in both directions, so an old certificate can understate today's cost badly — and one lodged at a peak can overstate it.
The building ages slowly. The pounds age fast.
So find the lodgement date before you take any £ figure off a certificate — how long an EPC lasts covers where that date sits. Recent costs are worth reading directly; older ones need re-pricing first.
Read the intensity, not the pounds
One figure does not have this problem: the energy use per square metre per year, in kWh/m². The intensity is a fact about the property. The £ total is that fact multiplied by prices somebody chose years ago.
It is the fair way to compare homes of different sizes — a large efficient house can post a bigger annual total than a small leaky one and still be the better building — and it survives price changes, so a rough figure at today's rates starts there.
One thing to know before you multiply: the headline intensity is a primary energy figure, which weights fuels rather than counting the units a meter records, so this method runs high — most of all for an electrically heated home. Treat what comes out as an upper bound and a comparison, not a bill.
- Take the floor area and the energy use per m² per year, both on the certificate.
- Multiply them for an annual kWh figure for the whole home.
- Apply the unit rates from a recent bill of your own — separately for gas and electricity, which are priced very differently — and add standing charges.
For something closer, the certificate's own heating, hot water and lighting cost lines can be re-priced individually, which is what happens when you look up a property's EPC.
The model assumes a household that is not yours
The estimate runs on a standard occupancy: standard heating hours, temperatures and patterns of use. Someone working from home all week, a household of five, and a couple who heat two rooms all diverge from it, in different directions.
That is the point rather than a flaw: one set of assumptions applied to every property is what makes certificates comparable. It does mean the number answers "how much energy does this building need", not "what will I pay". And where an assessor could not inspect something, the certificate records it as assumed — if a home's costs hinge on an assumed element, ask the seller before you model it.
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What this means for your offer
Running costs are a recurring cost of ownership, like council tax or a service charge. A home that costs materially more to run every year is worth less to you at the same asking price, and that is a legitimate input to what you are willing to pay.
The certificate gives you two figures to set side by side:
- The annual running cost, re-priced at today's rates — what the gap between this home and a more efficient one is worth per year.
- The certificate's own indicative cost range for the measures that would close that gap, and the score they would reach.
Those installation costs were priced in the certificate's year too, so they age the same way the running costs do: treat the range as a starting point and get a written quote for the largest item before you put a figure on the work.
The second figure comes from a document the seller commissioned, which is what makes it hard to argue with — you are reading their own paperwork back. The first is your own arithmetic on their certificate's energy use, so say so when you use it: a number you can show the working for is stronger than one presented as theirs. What the measures involve is covered in how to improve an EPC rating.
Be honest about what that gets you. An EPC does not entitle anyone to a discount and does not set a price. It gives you a case worth arguing — a documented, unaggressive way to put a number in the room. Whether it lands is a negotiation.
One caution on bands. Band D is the most common band in England & Wales, so "it's a D" tells you little on its own — what each EPC band means covers the score behind the letter. The money question is the annual gap between this home and an efficient equivalent, and the cost of closing it.
Where the rules stand (position as of August 2026)
Running costs are not regulated, but the certificate they come from is.
- Privately rented homes in England & Wales must meet band E, a minimum in force since April 2020.
- The rental minimum rises to band C on 1 October 2030, or its equivalent under the new metrics. This is confirmed, with one genuine caveat: what counts as equivalent under the new metrics is still completing its Parliamentary passage.
- The certificate itself is changing. New-style certificates using four Home Energy Model metrics, replacing today's single score, are announced for H2 2027, so how running costs are presented may change with them. Announced is weaker than confirmed; timing and detail can still move.
- There is no confirmed minimum band for selling a home. If you have read that sellers will need a C by 2035, that was a 2021 consultation ambition which never became policy — not a rule, and not something to price a purchase around.
General information, not financial or legal advice. Broc's scores and recommended ranges are informational guidance generated from data; outcomes vary and no result is guaranteed.
Frequently asked questions
How can I find out a house's energy bills before I buy it?
Start with its EPC, which estimates annual heating, hot water and lighting costs, then re-price those figures at today's rates — the certificate quotes them at the prices of its own year. Add what it excludes, including appliances and standing charges. Broc's free EPC checker will look up the certificate for any address in England and Wales without an account, and the seller's own twelve months of bills, if they will share them, are closer still.
Are EPC estimated energy costs accurate?
They are modelled, not measured, and assume a standard household rather than yours. As a comparison between properties they are reasonable; as a forecast of your bill they will be out, and the older the certificate, the further out the pounds in particular will be.
What does kWh per m² per year mean on an EPC?
It is the home's estimated energy use for each square metre of floor area over a year. Because it is a property fact rather than a price assumption, it stays useful as prices move, and it compares homes of different sizes fairly.
Do high running costs justify a lower offer?
They are a legitimate input to what a home is worth to you, and the certificate puts the annual figure and the indicative cost of the work in one place. That supports a case worth arguing. It does not entitle you to a reduction, and no certificate sets a price.
Broc
Broc is the badger behind trybroc.io — "broc" is Old English for badger. Where the estate agent speaks in superlatives, Broc speaks in evidence — sold comparables, days on the market, seller-pressure signals — and turns them into a number you can defend.
