This week we have received a new EPC for our place. We had it done because the last one has expired and we are thinking of putting the property on the market. I know there are different views of the value of EPC’s but it seems that people are finally taking notice of the energy rating before purchasing a property rather than just the size of the patio or whether the carpets and the walls are the mandatory grey in colour.

It seems all our efforts to improve the insulation in the place combined with solar PV and solar thermal panels have paid off in that we are now in band B (previously D).

I have a question regarding the estimated annual figures for the space heating and hot water requirement:

The annual heating figure in the new EPC is 9168 kWh and for hot water 2195 kWh – total 11,363.
1 litre of kerosene yields 10.35 kWh of potential energy. As my boiler is obviously not 100% efficient and is actually 90%, then I assume in my case that 1 litre of kerosene potentially would produce 0.9 x 10.35 = 9.31 kWh of “useful” heat. So 11363 kWh of useful heat would require the burning of 11363/9.31 = 1220 litres of kerosene.
This is odd because we use on average 1500 litres of kerosene p.a. combined with the fact that our solar thermal system provides us with hot water for most of the summer months and the boiler is off for weeks at a time. 1500 litres is equivalent to 13965 kWh (boiler efficiency 90%), some 2602 more than the EPC prediction.

My question is why is there such a large difference between the calculated and the actual oil consumption? Is the boiler less than 90% efficient? I’d be surprised, as it is only 4 years old and regularly serviced. Or is there some other factor that I am overlooking?

I’m just concerned because a prospective buyer (if a bit geekish like me) might question this inconsistency!

Thanks for any feedback.
Jeff

AFAIK you don't have to give any prospective buyer copies of your fuel bills for the years before the sale so there wouldn't be any inconsistency to worry about??

If the EPC paints a rosier picture, and that's the official energy use statement, then just let any buyers follow that rather than muddy the waters with conflicting usage.

There could be lots of reasons for excessive usage that would need investigation, potential remedy and then collecting meaningful usage data to show that youve fixed the problem.....a years worth??. You could have excessive ventilation losses, running the house hotter than the EPC expects, faulty heating controls, wrongly set up controls...are you running the boiler at condensing temps?

Posted By: philedgeIf the EPC paints a rosier picture, and that's the official energy use statement, then just let any buyers follow that rather than muddy the waters with conflicting usage.

There could be lots of reasons for excessive usage that would need investigation, potential remedy and then collecting meaningful usage data to show that youve fixed the problem.....a years worth??. You could have excessive ventilation losses, running the house hotter than the EPC expects, faulty heating controls, wrongly set up controls...are you running the boiler at condensing temps?

Having talked to an estate agent about this too, I will just refer to the EPC rating which at Band B (88) speaks for itself I guess. Obviously better than the D rating we got 10 years ago!

Oh I have lots of data regarding our energy usage! The first year after we moved in we were using 3000 litres of kerosene p.a. 18 years later we use 1500 litres p.a. The room stat is still set to 22C (my wife likes to keep the place quite warm) as it always was.

After a few years we ditched oil and went for a wood pellet boiler thinking we were doing the right thing environmentally. This was a disasterous decision as it turned out so we got shot of it 3 years ago and reverted to oil.

Posted By: Jeff B 2025

Having talked to an estate agent about this too, I will just refer to the EPC rating which at Band B (88) speaks for itself I guess. Obviously better than the D rating we got 10 years ago!

I think most people are years behind reality with what constitutes a low energy home and would be quite happy to live in a B rated house. As you say it's way better than average and quite respectable for a lived in retrofit

Edit to add: the difference between the 1200 and 1500 litres a year of heating oil is £180 a year.

At current mortgage rates, having £180 extra cash available each year would allow someone to afford to take out an extra £2700 on their mortgage towards paying a higher purchase price.

So really these kinds of sums can't make a significant difference to what price the house sells for.


But you really can emphasise and point out all the visible improvements such as recent double glazing, new boiler, any solar panels, new kitchen or bathroom, because each of those is £10k that the buyer doesn't have to budget for their own renovation and so can afford to increase what they pay on the purchase price.

It's galling when we have put huge effort into insulating our homes and we want to boast about it, but that's not what the buyer is interested to hear about!