What is taken into account in producing an Energy Performance Certificate?

Love them or loath them, Energy Performance Certificates (EPCs) are now a fact of life for home-owners, landlords, tenants and buyers. Whilst many people are now used to looking at the EPC certificate chart, which resembles those little stickers you find on modern electrical goods, few actually understand what goes into arriving at that score and what can, and can’t be done, to improve it.

 Whilst it is true that the software that calculates the score uses a wide variety of disparate information captured during the Energy Assessment together with a sophisticated computer model to calculate the score, the thinking that underpins it all is quite straightforward.
 
In order to arrive at a score, the software looks at three main characteristics:
  • The physical nature of the property, its size, shape, construction and age
  • How the property is heated and how hot water is produced
  • How the property retains heat
Some of these factors can be changed, the heating system for example, whilst others can’t, such as the fact that the property is detached. So when thinking about getting your property ready for market it’s helpful to know what can be changed and what will deliver the biggest bang for the buck. What follows doesn’t aim to be an exhaustive list of the elements used but is given with the aim of giving the layman, i.e. the person paying for the Energy Performance Certificate, a general understanding of their score and how it was calculated.
 
With regards to the property itself there is very little that you can do to improve matters. These characteristics are at the heart of the calculations. Essentially, the efficiency of any home will depend on the sheer volume of air that needs to be heated – the more air, the less efficient the house is. That’s why large houses with high ceilings are lovely to look at but expensive to heat. 
 
The single biggest factor at the heart of the EPC certificate calculation is how the property is heated. The calculation takes into account the fuel used, how it is consumed, how heat is regulated and how it is distributed. The choice of fuel can have a huge impact. The system favours gas and central heating which generally yields the best score. If you are off the mains, use electricity, oil or LPG your property’s score could be reduced by more than 20 points, a huge difference and one that might raise a red flag with a buyer or tenant.  So congratulations to everyone with gas central heating. 
 
The program will also reward owners and landlords who have installed modern condensing boilers, as this type of boiler is more efficient in the way it uses its fuel (and that goes for LPG and oil users as well). Likewise, anyone who has a programmer (the device that tells the boiler when to switch on and off along with temperature settings), room thermostat and thermostatic radiator valves (TRVs) can also expect extra brownie points. So if you want to improve your score significantly its worth looking here, although some changes could be expensive.
 
Last but not least, the calculation looks at how the property will retain heat and hot water once it has been generated. This is why shape and age of house is so important. If your house is detached every single wall just sits there radiating heat into the night air. If it’s a mid –terrace its party walls are nice and snug and being warmed by the neighbours. 
 
With so many incentives being given to homeowners to insulate their properties with cavity wall insulation, loft insulation and hot water cylinder lagging it will be no surprise to find out that these factors are also taken into consideration and can have a very significant impact on a properties score. In fact, insulating walls, loft and cylinder can literally double a property’s score taking it from being an energy black–hole to a shining star.
 
It goes without saying that there are a number of factors that aren’t taken into account including number of occupants, location, orientation and surrounding geography. However, before bemoaning this fact its important to remember that whilst we can compare £200 fridges we have never been able to compare the most important and expensive purchase of our lives and Energy Performance Certificates have provided a huge step forward.
 
So there you have it. At first it may look like your property’s score has been produced by magic with no rhyme or reason. The truth is that there is very little rocket science involved and the calculation uses common-sense principles that your grandparents would have known and understood. 
 
For more information about the EPC certificate you can visit the Communities and Local Government website