EPC estimate

danco

The EPC on my flat lists the estimated kWh used for heating. Is there a standard way this estimate is derived? Precisely, does th estimate rely on a specific temperature setting required for a specific number of hours on a specific number of days? If so, what are these figures? Or does each assessor make their own decisions?

The figures for my EPC seem accurate, but of course with Covid (and other reasons) I am at home and using heating much more than the estimate might have assumed.

Swipe

I wouldn't rely on an EPC for usage estimates. Everyone's usage is different depending on their energy patterns.

Verdigris

EPCs are done on a tick-box basis and where things can't be seen, without drilling holes or whatever, they are assumed (it will say assumed on the report) so they are not very reliable documents.

Reed_Richards

EPCs are done by an assessor feeding numbers into a software program.  In my experience even the assessor has no insight on how the software calculates its numbers so you will be lucky to find someone who can give you an answer.  

danco

Mine is a new build, and they have all the data about walls, glazing, etc. I understand that on older buildings the EPC can be significantly wrong, but I think it is likely to be roughly accurate for new builds. And of course energy patterns differ, which is why I want to know on what basis they estimate so that I can make a comparison of their estimated pattern with my actual energy pattern. As I mentioned in another thread it seems certain that my heating bill (communal heating, so separate from main electricity usage) is way wrong and that there must be a metering error. Comparison with the estimated usage from the EPC won't, of course, be accurate, but I am sure it will be better than a general comparison with flats of similar size and age.

Xbigman

EPC's are not worth the paper they are printed on. For one thing they don't take into account the number of occupants, it's all just generic averages. The average new build may have slightly higher specs than the average old property but it's a meaningless number for everyone except the lucky few who meet average criteria. 

Darren

matelodave

Over the years I've had five EPC's done and TBH none of them were worth the paper they were printed on.

None of the assessors really knew what they were doing, the info that they gathered was fed into a computer programme which couldn't actually take into account some factors and it then squirted out an estimate together with totally unrealistic costs and recommendations on how to improve the rating. Just my opinion you understand.

Verdigris

It's an opinion with which I concur.

It can sometimes be of advantage. If a property is for sale, with a poor EPC, if you know your building physics you can pick up a bargain.

danco

Can anyone actually answer my question instead of giving their opinions of the value of an EPC.

If I knew their criteria I could adjust to get my own estimate. And at least I can hope that the assessor took into account the unusual method of heating in estimating the kWh used.

If there is a better calculator I could use to make my own estimates of kWh used it would be helpful to know it. But I doubt if such a calculation would cover VRF communal heating.

Verdigris

You can look up the U-values of different types of wall/floor/ceiling/roof/window construction. Measure the areas of each and calculate the heat loss from that.

However, you'll need to be sure of the construction details of each element of your house to get an accurate result. This is why EPC calcs fall short. The assessors aren't trained surveyors and they can investigate further than what they see on the surface.

QrizB

danco said:

If there is a better calculator I could use to make my own estimates of kWh used it would be helpful to know it.

The best i know of is the MCS Heat Pump Calculator. While intended as an aid to sizong heat pumps, the spreadsheet will calculate your annual heating demand.

https://mcscertified.com/mcs-launch-new-improved-heat-pump-calculator/

danco said:

 But I doubt if such a calculation would cover VRF communal heating.

The method by which heat (energy) is supplied does not generally affect the amount of heat (energy) you need.