@af1 Despite the drawings for our extension showing that insulation was to be placed between flat roof and the ceiling, because the EPC assessor could / would not investigate if there was indeed the stated insulation in the cavity, he just marked it as ‘N/A’ and ‘Poor’. Maybe the fee paid to the assessor is not felt to be adequate but they seem unwilling to spend any time on such investigative work to ascertain the truth. Regards, Toodles.

Afaik different Assessors tske a different level of interest and attitude to use of evidence.

I believe they are obliged to accept:

• Building Control Certs
• Fensa Certs (windows/doors)
• MCS Certs (pv solar, ashp)

Evidence based on photos, material receipts, installer receipts etc is highly variable. Best clarify before appointment of assessor?

The problem will only get worse as property changes hands or comes up for recertification. How will a second or third owner prove previous works? If proven once should that be stored against the property for future?

Somehow the regs & guidance are going to need to take a common line - almost certainly involving a higher cost

@tim441 In my own case, I knew the insulation filled the roof void as I had had a new plasterboard ceiling fitted a while before - the drawings were from the pack handed to me by the previous house owners. My word nor the drawings were accepted as ‘proof’ though. Regards, Toodles.

Having carried out extensive work to further insulate the property with triple glazing replacing the old double, fitting solar panels and energy storage plus a solar power supplied DHW and an ASHP, I have almost been tempted to have a new assessment carried out - chances are though that the ‘score’ might have dropped! 😉 Regards, Toodles.

The guidance I was given suggested a regime that I consider fitting solar heated DHW and some solar panels; I have more than ‘leveraged’ my setup as I have added far more (8.1 kWp. of solar panels plus battery storage too as well as a Sunamp Thermino for the DHW) Then there is the heat pump - oh wait a minute … that probably means I have knocked the figure back and my ‘C’ has become a ‘D’ rather than a ‘B’!😉 Regards, Toodles. (Extract of improvement advice attached)

@toodles indeed.

the question of proof will only get harder and more inconsistent.

It will need addressing. Later owners will have less knowledge - let alone evidence.

As mentioned much earlier it's a reason I'm focused on getting an updated EPC even though existing has not expired. Working with an assessor who is open to going through it all and agreeing evidence.  

It's conceivable a future regime is an improvement. But amost certainly will then be increased cost.

What does the SAP/EPC scoring method have to say about the orientation of the solar panels?

Does it still count as 2kW if the developer has placed the six panels on a section of the roof facing north-east? 🤔 

@transparent Nothing on the south west side??? Toodles.

And further more, why so few panels fitted as there is obviously space for far more? If one has gone to the effort to fit a system, I would nave thought making the most of the space would be advisable. Rewards, Toodles.

The house is T-shaped @toodles.

The SW side has another part of the roof at right-angles to what's visible in the photo.

I would've put PV on that section facing SE, because it's still plenty large enough to have the six panels fitted to it.
But let's not get carried away and suggest that a national housing developer could use common sense!

@transparent Along with the right workers, they can’t buy any common sense.☹️ Toodles.

Finally, good news on my EPC assessment.

Having got (as was predicted) nowhere with Elmhurst Energy (accreditation scheme for my previous EPC) I have just commissioned a new EPC.

The original one, following completion of a major refurb in 2016,  was D 60 with potential to go to C 69. Having spent almost £300k on the renovation I was surprised and disappointed.

Since then the only change to the property is that we now have a "Smart" meter. And of course the assessment is under the latest RdSAP introduced in June 2025

I'd had enough of Elmhurst Energy and found a new local assessor with Quidos accreditation. Cost £100.

Result!!    Rating is now  C 72 with potential (with solar PV) to go to C 79.

My main gripe with the old EPC was that the ASHP was described as Poor. It is now rated as Good. 

It looks like the latest RdSAP model takes a more favourable view of air source heat pumps than in the past. Strangely the double glazing has gone the other way and is now only Average, rather than Good.

I'm not complaining and am pleased that the rating is a comfortable, not just marginal C. I think it is as good as I can get with a 150 year old detached stone cottage.

I won't be installing solar PV any time soon. The cost would be around £10k, for a projected saving of under £500 p.a. and still an overall C rating.

Having got the rating to where it should be I can go back to fretting about the lousy efficiency of the ASHP in sub zero temperatures such as experienced in the opening days of 2026. 

Mike