JamesPa Posted October 14, 2023 Share Posted October 14, 2023 What's a realistic value for air changes per hour in an older house (1930, solid wall) which has been fully double glazed (without tricks vents), has solid floor downstairs and carpet on floorboards up, and has extensive retrofitted iwi and no operational chimney. The 'standard' assumptions (for ashp sizing) say anything between 1 and 3 depending on room, but the only way I can make my calculated heat loss equal actual measured consumption is to assume 0.5 throughout, ie the figure that the standard assumptions give for a post 2006 house. To be honest, without mechanical ventilation (which my house does not have), I am struggling to imagine how the ventilation rate could be as high as the assumptions claim it is, but presumably they are based on something! Has anyone any idea whether 0.5ACH (or even anything sub 1) is realistic for a house like the one I describe, and if so do the standard assumptions in practice overestimate natural ventilation by a substantial amount in many cases? Any facts or other evidence that anyone has would be welcome. Link to comment Share on other sites More sharing options...
JamesPa Posted October 14, 2023 Author Share Posted October 14, 2023 Sorry for posting this here due to it issues/finger trouble. I have reposted in the correct (ie ventilation) topic! Link to comment Share on other sites More sharing options...
nod Posted October 14, 2023 Share Posted October 14, 2023 Get a quote and let them take the guess work out of it we had three quotes All seem to use the same software 1 Link to comment Share on other sites More sharing options...
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