Carrying out EPCs in central London on a daily basis means we do a lot of assessments for apartments within larger blocks. There are of course a huge range of flats, from modern buildings with new construction methods, to Victorian and older blocks that may have been converted from other uses.

We often get asked why a customers flat has a different EPC rating to another flat in a block, even though they may share many similarities, such as the size and layout. This can be a little confusing, and frustrating when you don’t achieve the rating you first expect. There are a number of reasons why this might be the case however.

Heating and Hot Water

Whilst some blocks will have a communal heating system, many have their own independent boilers or electric heating. Over the years, property owners are going to upgrade these systems as needed, so that over the years a building might have multiple different boiler types or other heating systems. This can have a sizable difference to the EPC rating, as heating is a key component.

Position of the Flat

Whilst the layout of the flat and the heating may be similar, the EPC rating takes into account the amount of heat loss area your property has. If you have a top floor flat with no insulation, this is going to score considerably lower than the flat just below you, even with everything else being equal. Top floor flats are the most likely to not meet the minimum energy efficiency standards.

When the EPC was carried out?

The way EPCs are produced have remained fairly similar over the years, but there have been small changes in the methodology and regular updates to the conventions every year. This means that an EPC done 10 years ago could be quite different to one carried out now – it is important to bear this in mind when comparing your certificate to others in your building.

I have new double glazing, why is my rating lower than my neighbour?

Double glazing, despite what the salesmen will tell you, only makes a small difference to the efficiency of a property. The EPC rating will only change by a couple of percentage points, so other factors are more likely to have the bigger influence on the rating.


If you have had any major works such as extensions, insulation work or renewable technologies, it is really important that you have the necessary documentation. If you have had any of the above completed on the property, please let us know and we will let you know what documents will be needed to give you full credit for these improvements. Without this evidence, the rating will likely not be as good as it could be.

Can you trust that the previous EPC is correct?

Whilst there is an auditing system in place to ensure the standard of EPCs are kept high, the EPC has been produced by a human, and is subject to human error. There are EPC companies that carry out assessments that we would not consider to be of a high standard, often paying their assessors a low per job rate that means standards are not always as high as they should be.

We would suggest that you should not read too much into the differences between you and your neighbour’s properties. There are so many factors that can affect the rating, that it would be nothing more than speculation as to why the ratings are different. If you are unsure as to why your rating isn’t where you think it should be, please get in touch with us and ask. We have carried out tens of thousands of EPCs in London and we will be able to give you expert feedback on what you need to do to improve your rating.