Yesterday I came across two energy efficiency rating barcharts for two different garden room designs. Great idea, I thought, what progressive thinking. These ratings charts are the same as given to new electrical goods and to houses, as part of the HIP pack when for sale. So, they are a familiar system of gauging energy efficiency.
I contacted a qualified energy assessor to discuss having our designs assessed on their specification. He related the difficulties and legalities in using these charts to sell garden rooms. Although he was happy to rate our buildings, the rating would NOT be indicative of the building when delivered to site and he advised against using it as an indicator of energy efficiency, with reference to trading standards.
Rating a garden room on energy efficiency depends on a variety of factors: insulation type and construction type, insulation placement, frame and glass types and the location of the building. The latter factor is the crucial one:
“Each individual garden room will have a different energy rating because of where it is to be located”.
I now know that wind, average local temperature and rainfall play a significant part in such calculations. A particular garden room placed on Shetland will have an entirely different energy rating from the same building, placed in Wimbledon. Don’t be fooled into accepting an energy efficiency rating as an indicator of the standard of performance of a garden room.