Hi Everyone,

I have now received a reply from the Department for Energy Security and Net Zero via my MP, a copy of which I have attached.

If my interpretation of their reply is correct, to quote from the reply, "EPCs produce an energy efficiency rating (EER) based
on the estimated running costs of the property", which would indicate to me that running costs is of primary concern rather than energy efficiency. Maybe it should be renamed a Cost Performance Certificate (CPC) rather than an EPC.

So it would appear that in the department's present opinion, it is more cost effective to have a gas boiler than a heat pump. 🙄 

In fairness the reply does go on to state that the Government is currently working on proposals for improving EPC metrics. I hope that you don't mind if I don't hold my breath.

Hi Everyone,

I have now sent this followup message and look forward to their reply.

Posted by: @prjohn

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The heat pump improves your energy efficiency, but does not show in your energy costs. 

I have not read any study about improvement in energy efficiency after heat pump upgrades under RHI scheme, but my cousin who lives in Australia experienced significant reduction in the energy costs. He got his electric resistance water heater upgraded to heat pump water heater under the state government scheme. I think the local climate and performance of the ASHP play a major role in this case.

@jamespipe 

I went from storage heaters to ASHP.  My energy costs are one third of what they were.  My EPC still has storage heaters listed as the main heat source and is rated average. Under the current system I don't think my ASHP will improve the rating but I don't know for sure. 

@kev-m When our EPC survey was carried out ahead of Octopus Energy conducting a feasibility survey for an ASHP installation, OE provided a link to a reliable agent and the fee was £50, this was in Jan./Feb. of last year; the rating turned out to be a C and the guidelines for improvements listed the gains to be made by installing PV DHW heating and also for installing an ASHP, we did both of these and a few other measures as well so I now use the ‘B’ (83) rating that should have resulted from these two improvements. I know not whether the addition of more solar PV capacity and battery storage would have affected these figures further but am disinclined to fork out another fee to get the uprated figure on a sustificate! Regards, Toodles.

I really should check my facts before writing;-) I stated that the EPC rating could be improved but it was not by replacing the (then) gas boiler with a heat pump but that I could install 2.4 kWp of PV. What I actually did was have 8.1 kWp of PV installed and the ASHP came after that so I think I’m a good ‘B’ now.;-) The assessor did make mention in the end notes about considering employing a heat pump but no other recommendations or details. Regards, Toodles.

Interesting comparative article from Passivehaus Trust on this subject EPCs as Efficiency Targets. A few years old, but I believe broadly relevant still.

As I understand it, EPCs lean towards running costs. I’ve not looked one recently, but the article implies that tucked away at the back is an environmental and fabric energy use value.

To add confusion, SAP reports seem to highlight the estimated notional Fabric Energy Efficiency, which appears to be an estimate of the annual energy use, the CO2 Emission Rate and the Primary Energy factor, which I believe is an attempt to define the total embodied annual energy use including generation, distribution, etc., all of these per m2 of the residence. As I understand it, it is referenced to a standardised notional house located in the East Pennines. The Primary Energy factor is the Fabric Energy Efficiency divided by the efficiency of the heating system and then multiplied by a factor related to the fuel type. There are standard tables of factors, I’ve lost the link I found, but if I remember correctly, gas is something like 1.13 kWh/kWh, while electricity is 1.5 kWh/kWh (although I’ve seen higher values). This would imply that using a heat pump would be better, as the efficiency might be regarded as the average annual COP. I expect that the electricity factor would improve as more renewables are added in the mix.

We have just had to have an insanely expensive differential SAP calculation performed due to getting carried away with glazing on a planned extension/refurbishment and falling over Building Control at step one with a bit more than the 25% glazing allowed by part L. This works on showing that the CO2 Emission Rate for the as proposed design does not exceed the rate for a design that just meets the Part L minimum requirements. We had allowed for this by making the refurbished walls considerably better insulated, so we passed, despite failing as it were (the results are compared to target values of a brand new house built to current part L standards). The report was conducted from the plans, with no site visit and no questions asked about the existing structure, the assessor just took notional values from SAP for the building type and age. The whole thing seemed like a fiddle to me, as the comparison was based on whole house figures (I.e. including the 60% of the house that we are not yet touching), so the final values will probably be watered down by the old stone building attached. On speaking to the assessor, I got the impression that the aim was to achieve a pass if possible. I was quite disappointed with the output (well not the pass), I was expecting a glossy fully detailed SAP report bound in velum, but just got a couple of top level PDFs with the pass result but not the detailed values used to determine these.

@rusty Ah! In that case, you should print them out (on velum of course) with full colour augmentations as per standard monk writing style, with a comprehensive set of footnotes (in at least three other languages of course). This should be accompanied by extensive indices and third party authenticity guaranteed endorsements and of course the full blessing of the MCS. The whole caboodle should then be hand bound in a hand tooled leather covering, adorned with ribbons and placed in a vault with duplicates in at least six other countries - err… will that do? Sorry, got carried away a little ther ;-))) Regards, Toodles.

@toodles you forgot the gold plated lettering. Yes, I was probably being unfair and a bit facetious, apologies for that, the assessor obviously put in the work, I was just frustrated with the detail of the output and the process. They said that they only provide what is required to convince building control, which is reasonable. I would have liked to have had the detail and some idea where improvements can be made, but I guess you only get that if you fail.

Link to some Primary Energy parameters: PE factors

@rusty Thinking some more about the whole business of EPC’s and the reasons for their existence, as the finished document is ‘published’ in electronic form, would it and should it not be made to be more helpful and informative to the occupier of the property were there further suggestions and links to guidelines on further improvements that might be considered / made? I am not thinking of anything too laboursome for the inspector / assessor; more a case of just references to a set of crib sheets detailing links for things like improving insulation, draught proofing measures, LED lighting and so forth. Mention of such measures as employing renewable energy for heating but just in a generic way without fear of endorsing particular products or installers; mention of further reading and links to MCS and other ‘authorities’ for guidance. We may not exactly be in love with such organisations but whilst they still exist, we must acknowledge this I suppose.

Those who are keen enough to follow any such links and guidance might feel they are getting better value for their buck and it might result in some further improvements being carried out. EPC’s may not be the full solution, but, might this help to make them more useful? Regards, Toodles.

The recommendations for improving a rating are often laughable.

A friend has a farmhouse  (277m2 floor area) with plenty of surrounding land. The building is a mixture of solid and cavity wall construction. It has no gas supply so heating runs on oil.

Several years ago he installed a ground source heat pump (with slinky coils buried under the lawn) to reduce his oil bills.

The house is still rated E with the potential to reach C. Insulation (except of the solid walls) is rated Good. The double glazing is rated Average, as are the heating and hot water (running as they do on the heat pump). This is better than the Poor rating of my ASHP, but not as good as the Good rating of a gas boiler.

The recommended improvements to get a better rating  (in order), were:

Wall insulation

Insulation of solid floor

low energy lighting

Heating zone controls

Solar PV panels

Wind Turbine!    This last item was at an estimated cost of £15k - £25k to save a very precise and projected £633 p.a.  (certificate date was Feb 2020, so before recent price hikes).

Estimated annual energy use for heating and water is 43,000kWh!

Mike