I am trying to figure out the best way of tackling ventilating bathrooms or kitchens when they form part of a new residential extension that has been given an energy efficient envelope to Carbonlite silver standard, and a MHRV system is not possible for the whole house or for the extension.
Do I have an uninterupted envelope and let the users open the window for hopefully short times?
Do I put in a single point heat recovery unit like the 'long' HR25 byVent Axia, but always have a 152mm dia heat hole in my fabric? Or am I worrying too much about the constant low heat loss through the wall? What happens if one reduces the thermal loss through the wall to 0.15W/sqmK or lower, does the inclusion of a ventilator then make an important impact?