We’ve been making a lot of effort insulating and sealing up our house in order to save money on our bills and reduce our CO2 emissions….so there is no point punching lots of holes in it in the bathrooms and kitchen….equally we don’t want a damp and (smelly) house. One option would be to install a whole-house mechanical ventilation with heat recovery (MVHR) system and another is to install individual room heat recovery units in the key areas.
Both work on similar principals – exchanging heat from moist smelly internal air to the fresh outside air as the first is expelled and the second is introduced into the house. They do this by passing them through heat exchangers.
I’ve estimated that the running costs of the four fans will be around £48 a year if we didn’t have a PV system. With the contribution from the PV system and the fact that the boost Wattage will not be on at night I estimate it will cost us around £27 a year in electricity.In terms of heat energy, they will of course lead to greater heat losses than a totally sealed bathroom/kitchen but the realistic would be a 0% heat recovery normal extractor fan which would lose a lot more heat. I’ll calculate the heat savings over a normal extractor fan in a follow up posting when I install them.