EPC reforms will be sensitive to individual properties claims government

There are going to be even less properties in the PRS by 2029 so whatever the ‘contribution’ the sector was assessed to originally have, will have dropped. It is very questionable as to just how much Co2 ‘savings’ will be saved by continuing to push the NZ agenda in this sector, especially as the majority are D as it is, and many will still be exempt anyway.

All totally pointless.

EPC articles always talk about houses, never flats, where one’s options are limited.
My biggest bugbears about EPCs are
1 the utter lack of transparency over what building works generate what points, so I can’t tell whether the work I might be about to spend thousands of pounds on is going to have the desired effect on the EPC
2 the way points are allocated on “assumed” features, not actual heat loss data. In a flat, for example, one may be unable to either access the data or dig around in the fabric of the building.

Reply to the comment left by Jenby at 21:31
Jenby, I think this is perhaps misunderstanding what an EPC is actually designed to do, particularly when it comes to RdSAP and the use of assumptions.
RdSAP is a standardised methodology, not a survey of the actual thermal performance of a building. It has to be capable of producing a consistent assessment across millions of existing dwellings, many of which have construction details that simply cannot be established without opening up walls, floors, roofs etc.
That’s why the methodology has an established hierarchy of evidence and, where the necessary evidence isn’t available, default/assumed values are deliberately used. This isn’t the assessor guessing, nor is it an attempt to suggest that an assumed feature is necessarily what is physically present. It is a fundamental part of making an EPC assessment achievable at a reasonable cost and without destructive investigation. The assumption is the thermal performance minimums of building regulations at the time of construction.
The same issue applies to flats. If you’re assessing a flat in a block and you can’t establish what is inside a particular wall, floor or ceiling, it would obviously be unreasonable to expect the assessor to start drilling holes or removing finishes. The methodology provides a standardised way of dealing with that uncertainty.
I’d also question the idea that EPCs allocate “points” to individual building works. That’s not really how the calculation works. The rating is the outcome of the calculation for the dwelling as a whole. The effect of an improvement depends on the particular dwelling and its existing construction, geometry, heating system and other characteristics. Consequently, there isn’t a universal answer to “how many EPC points will I get for spending £X on insulation?”
If someone is considering spending thousands of pounds specifically to improve an EPC rating, the sensible approach is therefore to have the property properly assessed and discuss the recommendations with an assessor who understands the methodology, rather than expecting the EPC to operate as a simple points-based system.
There is certainly a legitimate debate to be had about whether the EPC methodology is the best way of representing building performance. But criticising RdSAP because it uses assumptions rather misses the point: the assumptions are there precisely because it would otherwise be impractical and prohibitively expensive to establish every construction detail in an existing dwelling.
For flats, there are also legitimate practical limitations around what an individual leaseholder or landlord can actually alter, but that’s a different issue from whether the EPC methodology is working as intended. In fact with flats they are in a great position if the leaseholder can get a letter from the freeholder denying permission for floor/wall insulation/new windows/roof insulation because the Consent exemption can then be used for those improvement measures.

Reply to the comment left by Jenby at 16/09/2026 – 21:31
Jenby, I think this is perhaps misunderstanding what an EPC is actually designed to do, particularly when it comes to RdSAP and the use of assumptions.

RdSAP is a standardised methodology, not a survey of the actual thermal performance of a building. It has to be capable of producing a consistent assessment across millions of existing dwellings, many of which have construction details that simply cannot be established without opening up walls, floors, roofs etc.

That’s why the methodology has an established hierarchy of evidence and, where the necessary evidence isn’t available, standardised assumptions are deliberately used. This isn’t the assessor guessing, nor is it suggesting that an assumed feature is necessarily what is physically present.

In fact, the assumptions are generally based on the minimum thermal performance that would have been required under the Building Regulations applicable at the time of construction. So if you have an older property where you can’t prove what is inside a wall, RdSAP doesn’t just pluck a U-value out of thin air. It uses the prescribed methodology and conventions for that age and construction.

This is fundamental to the whole point of RdSAP. It was introduced as a reduced-data, lower-cost method of assessing existing dwellings. The alternative would be requiring vastly more information — and potentially destructive investigation — in order to establish exactly what is inside every wall, floor and roof. Government’s own description of RdSAP specifically explains that it uses assumptions about existing buildings to reduce the amount of information that has to be collected.

The same applies to flats. If you’re assessing a flat in a block and you can’t establish what is inside a particular wall, floor or ceiling, it would obviously be unreasonable to expect the assessor to start drilling holes or removing finishes. The methodology provides a standardised way of dealing with that uncertainty.

I’d also question the idea that EPCs allocate “points” to individual building works. That’s not really how the calculation works. The rating is the outcome of the calculation for the dwelling as a whole. The effect of an improvement depends on the particular dwelling and its existing construction, geometry, heating system and other characteristics. There therefore isn’t a universal answer to “how many EPC points will I get for spending £X on insulation?”

If someone is considering spending thousands of pounds specifically to improve an EPC rating, the sensible approach is to have the property properly assessed and discuss the recommendations with an assessor who understands the methodology, rather than expecting the EPC to operate as a simple points-based system.

And actually, flats can have another advantage that is sometimes overlooked when we’re talking about MEES. If an improvement requires the consent of a freeholder, superior landlord or another third party, and that consent cannot be obtained despite reasonable efforts, there is a specific third-party consent exemption under the MEES regulations. This is particularly relevant to flats where, for example, external wall insulation, changes to communal elements or other works to the building fabric may require freeholder consent. It isn’t an automatic exemption simply because the property is a flat, but it is a recognised route where the necessary consent genuinely cannot be obtained.

So I don’t think the existence of assumptions is really a criticism of EPCs. They’re a necessary and deliberate part of a methodology designed to assess existing buildings without turning every EPC into a building survey.

There is certainly a debate to be had about whether the methodology is the best possible way of representing energy performance. But if someone doesn’t understand why assumptions are used, I think the answer is to explain how the methodology works rather than conclude that the assumptions themselves are a problem.

I have 2 ex-council 3xbed flats in Islington London with EPC = D, but cannot get any answers from the council regarding the advice on the EPC to upgrade to ” Internal or external wall insulation £4,000 – £14,000″ Unsure what to do – I guess their bill if external or my bill the internal?

Reply to the comment left by LIZZY7 at 19/09/2026 – 08:22

Lizzy7, I wouldn’t assume that you necessarily have to install the insulation.

The new England & Wales MEES proposals specifically introduce a Solid Wall Insulation exemption. If, under the new HEM assessment, solid wall insulation is the only remaining measure needed to bring the property up to the required fabric standard, the landlord can choose not to install it and register the exemption.

That’s particularly relevant to flats where the external walls are part of the wider building and the landlord may not even have control over what can be done to them.

I’d consider waiting for the properties to be assessed under the new HEM methodology rather than spending £4k–£14k simply because the current RdSAP EPC recommends wall insulation. You may find that other measures get you to the required fabric standard, or that SWI is the only remaining measure and you can use the exemption. You’ll then, of course, need to satisfy one of the secondary metrics as well (Heating System / Smart Readiness).

The new methodology is currently expected to be available for calculation in late 2027, running alongside the current methodology until October 2029. So from late 2027 you’ll be able to make much more informed choices about what, if anything, actually needs doing.

Reply to the comment left by Reluctant Landlord at 15/09/2026 – 14:22
Hopefully we will have got this clown government out by then. I have a Victorian property which would be very expensive and difficult to get up to category C no way I’m going to bother for what I get out of it I’ll sell up

Reply to the comment left by Bilivino at 19/09/2026 – 10:28
very good advice. It’s quite possible that all this will be watered down in any case due to cost

Reply to the comment left by Bilivino at 18/09/2026 – 20:35
I understand what you mean, but my point is that there should be an accepted alternative to measuring energy performance where the current EPC methodology causes an artificially low score. If EPCs were simply for guidance, it wouldn’t matter so much, but poor EPCs are a death knell to many rented properties because of PRS legislation. This isn’t helping anyone.
The guidance on EPCs is poor and unrealistic. If it says to do wall insulation, for example, what thickness, what materials, all walls or some… Just as an example.

Reply to the comment left by Jenby at 23/09/2026 – 10:45
I think you still present a couple of misconceptions here.

Firstly, the suggestion that an “assumed” element will result in an artificially low EPC rating isn’t really how RdSAP works. For that to be the case, the actual thermal performance of the building would need to be significantly better than the performance assumed by the methodology for that particular construction and age. In practice, that would generally mean the building has been constructed to a standard substantially better than the minimum requirements applicable under building regulations when it was built.

That can certainly happen — a good example would be something like a Passivhaus or another unusually well-insulated property — but RdSAP makes provision for this. Where there is appropriate documentary evidence of the actual construction/U-value, the assessor can enter the actual U-value rather than simply using the RdSAP default.

So the issue isn’t that RdSAP is deliberately giving properties an artificially poor score. It’s that if you can’t demonstrate that a building performs better than the standardised assumption, the methodology has to use its prescribed assumption. That’s a methodology convention, not an assessor’s guess. This is really more an education issue about how RdSAP works.

On the point about the EPC recommendations being “poor and unrealistic”, I’d suggest looking at the actual RdSAP 10 Specification document, which is publicly available on the Building Research Establishment (BRE) website. Section 20, Table 33 sets out the basis on which the improvement recommendations are generated. For example, for both internal and external solid wall insulation, the specification doesn’t simply say “put some insulation on the wall” — it specifies improvement to a wall U-value of 0.30 W/m²K.

And there’s another important point here: the EPC recommendation isn’t a Building Regulations specification or a substitute for one. If a landlord actually decides to carry out internal or external wall insulation, the work itself is subject to the relevant Building Regulations requirements, including the applicable thermal performance requirements and Building Control notification/approval arrangements. The best part of that is the BC completion certificate then provides an excellent starting point for your documentary evidence to give to your energy assessor next time round.

So the EPC can identify a potential improvement and model its effect, while Building Regulations govern how the actual building work is carried out. Those are two different things.

I completely agree that landlords need better information if they’re contemplating spending thousands of pounds. But the answer isn’t necessarily to abandon the standardised methodology and measure actual heat loss for every property. There is a considerable amount of publicly available technical information behind RdSAP; the more useful question is whether people have been shown where to find it and how to interpret it.