By Chris Dunham
The answer in my case is that my 1977 house would pass current Building Regulations for new homes built in 2020. That you might think is a surprising credit to the quality of UK 1970’s housebuilding. But as my air tightness tester said “It’s not that your house is good, it’s that Building Regulations are s**t.”
So what’s involved in finding out how leaky your home is? An air tightness test will cost you about £500. For that you get your front door temporarily displaced by a giant fan surrounded by plastic and someone wondering round your home taking photos in glorious infrared of your leaky areas.
Finally you get a report detailing of this with recommendations as to what you should do to fix all the problems identified.
My rationale for having this done was that, as part of a whole house retrofit, we are having a mechanical ventilation with heat recovery (MVHR) system fitted. This system extracts stale air from the house and introduces fresh air from outside. But rather than just bringing in fresh air at whatever temperature it is outside, the air is preheated via a heat exchanger by the outgoing stale air – heat recovery is in the name – thus reducing our heating demand.
For this system to work effectively you want all of your ventilation to done via this system. If your house is already adequately ventilated by gaps and holes in the house then you’re introducing unnecessary additional ventilation by adding the MVHR. What would be the point?
So what did I discover about my house? Perhaps the most revealing finding was just how much heat loss was being cause by gaps (shown below) around one pipe as it enters the loft. This pipe runs through the whole house and out through the roof. I have no chimney but effectively this was acting just like one sucking air from the living room, bedrooms and bathroom via a serious of interconnected ducts.
Ultimately the benefit was that it gave me a real clear list of exactly what I needed to fix before installing the MVHR.
If you’d like your leakiness exposed, you can contact doorfanman@hotmail.com.
