When completing a domestic energy assessment in order to provide an EPC (Energy Performance Certificate) for a home, the first thing you need to do is measure exactly how much space needs to be heated. In other words you have to measure the volume of the dwelling.
Although many domestic energy assessors will also offer a floor plan service, especially if they are working for estate agents, in truth an EPC has no need for measuring the size of individual rooms in a house.
The exact dimensions required are the macro dimensions, the overall size of the house. The plan that is drawn up by the assessor for the EPC will have rooms marked on it but the exact measurement of each individual room is unnecessary.
In detached houses and easily accessible semi-detached houses the accessor will measure the dimensions of the house on the exterior. For flats, maisonettes and terraced homes the measurements will be taken on the inside. The method used has to be selected in the software so the calculations are automatically adjusted.
Every nook and cranny has to be considered, as long as there is floor space it is measured. This is why you’ll see assessors measuring bay windows carefully, as every area has to be included, no matter how small. This is why you won’t find a domestic energy assessor who doesn’t know the formula for finding out the square root of a trapezium! It’s ½ (A+B) x h if you’re interested?
If you have a cut out for your porch, or your unheated garage is part of the main property then these will have to be removed from the calculations. Any upstairs floorspace above a garage may have to be treated as an extension as its floor make up is different to other parts of the house.
Speaking of extensions, all of these are measured separately, after all they were probably subject to different building regulations.
Finally, the easy part, measuring the ceiling height. Times them all together to get the total volume that you have to heat, then on with the rest of the EPC. Thank goodness for laser measures!