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What Affects an EPC?

BEST Compliance get asked many times by clients why their EPC’s come out with a poor rating, there are many factors that affect this including: Activity of building, offices always come off worse than a warehouse storage due to the high demand of electricity and heating. 

  • Age of buildings, for example older single skin solid walls have much higher heat leakage levels than a newly constructed one
  • Orientation of the building, can it maximise the natural daylight. 
  • If its got a neighbouring property, adiabatics always help the heat loss. 
  • Air permeability of the property (doors, chimneys etc) if there is a lot of air coming into the property 
  • Glazing, has the building made use of double glazing to lower its U values. 
  • Heating, Ventilation & Air Conditioning (HVAC) Systems. How’s the building heated/cooled and how is it controlled 
  • Lighting and Controls, what bulb and light fittings are used and how are they controlled. 

The list goes on but these are just a few conditions that affect the rating. 

As the person responsible what can I do to maximise the EPC rating for a low cost ?


BEST Compliance will always recommend a cheap and mostly advantageous improvement, this would be to swap all the pendant light fittings in the property to LED equivalents

It should be noted in most cases this can dramatically improve the rating by at least a whole grade, but there are some instances that improvement isn’t as great. Some of the older incandescent lights are that inefficient at producing light , 70 of the 100 Watts go on heating, the programme that produces the EPC takes this into account in the heating element of the building. So when you swap these to LED the programme instantly has to get heat from elsewhere in the building, normally an electric heater, as there both very similar efficiency no real improvement has been gained, but cost savings will show in the lighting.

HVAC (Heating, Ventilation and Air Conditioning)

EPC’s really don’t like Electric heating in poorly insulated properties (pre 1995), the programme has rules to which you must know in producing commercial EPC’s one of these many many rules states: if no heating is present in a room, except for a few exceptions the HVAC must be set to Electric heating, it states this as the default setting, or even easier to understand the worst case scenario. There are occasions when you have very little alternative but if you can remove them, for instance if you have a radiator in the room, please do so.

Building log book documents 

Its imperative these days to keep a building log book, in here you will keep all your building documents, plans, fire risks, fire alarm, Insulation, Boiler Installation certificate, Gas safety checks etc. 

When our assessors come to site we will always ask you for any documents on the property. We are mainly looking for scaled plans if there are any, so we can speed up the survey especially if its a confidential visit also if any extensions have been built, and more importantly model numbers for the HVAC, the date roof and wall insulation was installed and the U value it adheres to and if any glazing has been installed again what year it was installed. 

If these documents are not available, the assessor will use their experience and visual surveys to determine this, although were very good at finding this information out sometimes its not possible and it has to go into the programme as a default year or our best estimate. 

Any Special Installations 

If any renewable energy or underfloor heating is installed its best to ensure all documentation is present or sent via email to BEST Compliance so we can get accurate results.