There isn’t a great deal of understanding as to what actually constitutes the surveying process of an EPC (outside of the surveyors themselves, of course). What can you expect the surveyor do when he gets to your house? How does the process work? In this blog and accompanying video, we are going to show you exactly what is measured and what evidence is gathered – not in enough detail for you to do it yourself, but just enough so that you understand what is going to go on during the visit!

Checking your loft insulation

The assessor will do a quick head-and-shoulders inspection of your loft, if it is accessible. The depth of the insulation will be measured, and the type of party wall between you and any neighbouring property will be checked. Access to the loft is really important if you want a good rating, because the assessor can only input what he can see and take evidence of.

Wall thickness, type and insulation

The type of walls your property has is very important. Solid walls and cavity walls differ greatly in terms of their insulating value, and will therefore impact on the energy rating. The assessor will measure the thickness of the walls, and check for any insulation that is present.

Checking the model of your heating system

If you have electric heating, a model number is not required; the assessor will just check what rooms are heated and the general type of heater you have. If you have a boiler or a heat pump, the exact model of the boiler will be useful to give a more accurate rating. The assessor will also look to see whether you have a thermostat, a programmer, thermostatic valves, and any other heating controls that may be present.

Your hot water heating

Hot water heating may come directly from your combi boiler, for instance, in which case this will not be relevant to you. If you have a hot water cylinder however, then the surveyor will check its capacity and the insulation present.

Your windows

The type of window you have – for example, single, double or triple glazing – and the age of the windows will be checked. With double glazing, the width of the gap between the window panes may also be measured. With single glazing, the draught-proofing present is checked as well.


The number of lights in the property and the number of energy efficient lights are checked.

Your bathrooms

The assessor will add up the number of rooms in the property classified as ‘habitable’, excluding rooms like utility rooms and small kitchens. They also add up the number of bathrooms present and the number of showers and baths.

Renewable technology

If you have any solar panels, solar thermal, wind turbine or any other type of renewable electricity or heat generation, then this will need to be considered as well. The size of the system is the main concern here.

Creating a floor plan

Once all this evidence has been gathered, the assessor will then create a simple floor plan of the property to work out the area of the property and the amount of heat loss and partition walls. This is much more basic than the floor plans typically carried out by an estate agent, and it is kept in a draft form only for the purpose of calculations. We often get asked if we can produce floor plans for the client as well as the EPC; this would add an additional cost, simply because it is beyond the remit of the EPC and these basic sketches.

Photographic evidence

As the surveyor goes around the property, they will need to take multiple photos to gather evidence to support why they are entering certain values into the software. This is because a percentage of the work carried out by EPC assessors is audited by our accreditation body, and it is essential the surveyor can justify why they have entered a certain value.

Documentary evidence

If there are things you have installed, like wall insulation, room-in-roof insulation, or floor insulation for example, that are not easily able to be measured on the day, the surveyor will need to see documentation showing exactly what has been installed. If this is not available, the benefits of this insulation will not be included in the final EPC, as the assessor has to be able to show it is present during an audit.

Producing your EPC

Following this visit, your EPC is created using all the measurements and evidence gathered on site. This is usually done back in the office and you will get your EPC within 48 hours in most cases. If you have any questions about how an EPC works or what is involved in the survey, just let us know! This blog covers some of the most basic parts of the survey which is usually required in every home, but there are various additional items that need to be recorded, depending on the home in question. Every home is a little different!