Preparing for your EPC assessment

Quotes, ratings and older EPCs

The full answers to the questions we’re asked most.

Your quote and property complexity

We price from the details you send before the visit. If the home turns out to be materially different, for example a bigger floor area, a different property type, or an extension or loft conversion that wasn’t mentioned, we’ll tell you before we start. We then agree a revised price with you or reschedule, and you’re free to cancel at no charge at that point. We never change an agreed price without speaking to you first, so there’s no surprise on the invoice afterwards.

How your EPC rating is calculated

Your assessor surveys the home, records how it’s built and heated, checks the evidence and enters it. Approved software then calculates the rating using the government’s method. No assessor can raise or lower a score to order. If they could, the certificate would be worth nothing to the buyer, tenant or lender relying on it.

That includes us. We can’t change your rating, before or after the visit, and we can’t lodge a different one because it was expected or needed for a sale, a let or a mortgage.

What we can do is make sure everything that’s really there gets recorded and backed by evidence. Have your paperwork out on the day, or send it to us before the visit: the documents section shows what helps.

What counts towards your rating

Many homeowners renovate and then find the rating hasn’t moved as far as they hoped. Two things are worth knowing:

• Not every change counts towards an EPC rating. The EPC measures a fixed set of things, so work that makes a home nicer, or even saves energy, may not move the score.
• The higher bands are much harder to reach. Going from C to B takes far more than moving between the lower bands, and it usually needs solar panels.

Some examples of what does and doesn’t count:

• Loft insulation at both the floor of the loft (the joists) and the roof slope (the rafters): only the joist insulation is counted, so the rafter insulation adds nothing to the rating.
• Underfloor heating run from the same boiler as your radiators: both are recorded, each with the same boiler, but the rating follows the boiler far more than how the heat is delivered, so the underfloor only moves it a little. With a heat pump, if radiators heat half the floor area or more, only the radiators are counted.
• Hidden insulation only counts with paperwork that shows the thickness.
• The loft: if there’s no loft hatch or other way in, it’s recorded as no access and the method uses the default for the age of the home. So if your loft has no insulation at all, the rating may be better with no access to the loft, where the default for its age is used, than with access, where none is recorded. If you can get into the loft, your assessor measures the insulation that’s actually there. A hatch that’s there but can’t be opened on the day is recorded as access with the insulation unknown, not as no access.

These rules are set by the government’s method, not by us, and we can’t change them, so we can’t promise a particular rating before the visit. If you want to know where you stand first, an EPC Pre-Assessment gives you the rating without lodging it, and the EPC Improvement Plan puts the upgrades in order for your home.

Why your EPC may differ

Ratings are specific to each home. Two homes that look the same from the street can score differently, for good reasons:

• Position in the terrace: a mid-terrace home has fewer outside walls than an end-terrace or a semi
• Floor area, layout, extensions and loft conversions
• How the walls, roof and floor are built and insulated
• Loft insulation depth, and whether the loft can be inspected
• The age and type of the windows
• The boiler, heating controls and hot water cylinder
• Heat pumps, solar panels and batteries
• Lighting
• Paperwork: one home had evidence of its insulation or windows, the other didn’t
• When it was assessed: before RdSAP 10 in June 2025, or before a later update to the method’s rules
• The method used, and what was recorded at the last assessment
• Occasionally, a mistake on one of the certificates

Comparing EPCs? Compare the property details on each certificate, not just the letter. Why EPC ratings differ between similar homes

The method changed in June 2025: RdSAP 10

Existing homes have been assessed under the updated RdSAP 10 method since 15 June 2025, replacing the approach used for older EPCs. RdSAP is a reduced-data version of the full SAP calculation. It’s used for existing homes because the complete construction data a new-build assessment relies on is rarely available for a home that’s already standing.

Older and newer EPCs may differ because the method, the data it needs, the evidence for the home and the technologies it considers have all changed. That’s a change in how a home is assessed and recorded. It isn’t a judgement that older homes or older building standards are now “bad”, and it isn’t a requirement to modernise anything.

The standards have moved on too. Heating, insulation and glazing have improved a lot in the last decade, and the method’s assumptions, such as fuel prices and how each system performs, are updated to match. So a home that hasn’t changed since its EPC five or six years ago can score lower today, because it is now measured against newer standards. It doesn’t always go down: it depends on the home.

So a new EPC shouldn’t be expected to reproduce an older certificate exactly, even if the home itself hasn’t changed much. An older EPC reflects the method and information available at the time; a current EPC assesses the home using today’s approved method.

That doesn’t mean an older EPC was automatically wrong, or that RdSAP 10 will always produce a higher or lower rating. The result depends on the home, the features present, the evidence available and the method used. RdSAP 10 is the approved method for existing homes in England and Wales under the current GOV.UK notice of approval.

Older EPCs can also hold different assumptions or recorded information. If an older certificate looks inconsistent with the home, compare the property details on it rather than the letter alone. Genuine errors are possible, though they shouldn’t be presumed. What changed in RdSAP 10 · GOV.UK notice of approval

When your rating comes back

The questions we’re asked most once the rating is in, answered straight.

My old EPC had a better rating. Why has it gone down?

Older EPCs were done under earlier versions of the method, some well over a decade ago. Standards and assumptions have moved on since, so some things that used to score well don’t carry the same weight now. Since June 2025, existing homes are assessed under RdSAP 10, which is more detailed. A new EPC isn’t a like-for-like comparison with an old one, even if the home hasn’t changed. The method changed in June 2025

Similar homes nearby got a B. Why didn’t mine?

Their EPCs may have been done before June 2025 under the older method, or may have expired. Homes that look alike can also differ in floor area, how many outside walls they have (an end or mid terrace), insulation, heating, and the paperwork that was available on the day. Compare the property details on each certificate, not just the letter. Why your EPC may differ

I’ve done a lot of work. Why hasn’t the rating moved more?

An EPC counts specific things: insulation, windows and doors, heating and hot water, heating controls, lighting and renewables such as solar panels. Changes like dividing a room with partitions or curtains, decorating or new flooring don’t count. Some upgrades count for less than people expect, and going from C to B usually needs solar panels. What counts towards your rating

My loft has 300 mm of insulation. Why wasn’t it counted?

Insulation can only be recorded if your assessor can see and measure it, or if you have paperwork that shows it’s for your home and states the thickness. If the loft couldn’t be reached, or the insulation was covered, the method has to use a default instead. Send us the paperwork with the thickness before your EPC is lodged and we’ll check whether it can be recorded. Documents that may help

I sent photos and documents. Why can’t they be used for my wall insulation?

Insulation inside a wall can’t be seen, so it’s recorded from evidence that clearly relates to your home, to those walls, and to the work being done, and that shows how thick the insulation is. Documents about other work, such as the loft or the windows, can’t be used for the walls, and a photo with no measurement can’t show the thickness. An extension is recorded separately from the main building, so it needs its own evidence too. What helps: a Building Control completion certificate, the installer’s guarantee or specification stating the thickness, or photos taken during the work showing the insulation with a tape measure against it. Your assessor has to be able to rely on it, so we’ll tell you if something can’t be used. Documents that may help

I have insulation at the loft floor and in the roof slope. Why does only one count?

Where a loft is insulated at both the joists (the loft floor) and the rafters (the roof slope), the method counts the joist insulation only. We can photograph and note what we see, but the rafter insulation won’t change the rating.

It’s only a point or two off the next band. Can you adjust it?

No. The rating is worked out by approved software from what was recorded and evidenced, and we can’t move it, even by a point. That stays true if the home isn’t being sold or let, or the EPC is for your own records. If you have paperwork for something we couldn’t see, send it before the EPC is lodged and we’ll check whether it can be recorded. How your EPC rating is calculated

Is a C a good rating?

Yes, it’s a strong result for an existing home. The current legal minimum for letting a home is E. The government has confirmed a C target for rented homes from 1 October 2030, but that still needs legislation.