EPC conventions 5.0 states that k*****n extraction rates and associated SFP's should be included within the EPC calculation to account for the increased volume of fresh air entrained into the building which will need to offset with heating/cooling energy. Now for domestic type kitchens (for example within a student residence apartment) there is a suggestion that 15ACH should be used if actual figures are unknown. This to me sounds extremely excessive for an extraction fan that may operate for between 0hrs and say 2hrs per day max. I would think that if such very infrequent usage of an extractor fan can be justified (based upon the type of k*****n being served for example and the fact that manual switching of the extractor would be required) then the necessity to include an allowance for dedicated k*****n extract can be ignored or a very low ACH applied that is averaged over a 24hr period.
This may sound obvious, though if the extractor hood operates in recirculation mode only, then I would presume that there is no requirement to include this within the EPC calculation.
Thanks in advance for any thoughts on this. Once we have reached a consensus then it would be useful to clarify whether the Part L2a 2013 methodology would follow the same approach.