Chris Morgan, Director at John Gilbert Architects
MVHR (Mechanical Ventilation with Heat Recovery)
UK building regulations got themselves into an almighty mess when it came to airtightness and ventilation, they still are. To the point that, where the airtightness is ’too high’ they recommend putting bigger holes in the building fabric to avoid problems with moisture. I had it out with them various times and they simply couldn’t see past this issue. The reason I got into Passivhaus was initially twofold, one was the relative accuracy of PhPP compared to SAP and the other was that the only way I could see through the ridiculous airtight / ventilation nonsense was MVHR! I still believe it is more useful than most people realise.