Reading Leo Hicks’ article on Tomas O’Leary’s passive house in Wicklow, The Guardian Weekend, May 10 2008, it was refreshing to find that the weary list of eco tips which always includes “turn your thermostat down a degree” had a useful addition.
Alright, well the no. 1 tip of “get some cavity wall and/or loft insulation” was still there, but rightly so too. You can’t argue with that one, since 60% of your heat is going to escape through walls and roof.
The rest of heat we generate, either through our inefficient bodies, or some form of centrally heating, is likely to escape in an unplanned fashion, through windows and doors, and via all the holes in the fabric of the building.
The interesting fresh piece of advice then, was to bring in some people to do a pressure test. In the article, it states that pressure tests start at about £70. These are usually carried out on new-build properties, to check whether houses comply with building regs for air-tightness.
Basically it works by having air pumped into the house, to see what, if any resistance there is.. ie is everything that is meant to be keeping the house airtight, actually doing its job?
We’ve got a 1930s purpose built flat, with big single glazed sash windows at the front, and a two fairly ill-fitting exterior doors, and a handful of vents from before the cavity was insulated. I’d be surprised if we can get enough pressure up to actually measure the leaks.
But how airtight are you trying to get a place? If you do too well, you are going to end up with a stuffy, stale, low-quality air. If it’s too tight, then you’re going to need mechanical ventilation. If too draughty, you’re going to lose too much heat. The solution lies in between the two.
More on this anon. In the meantime check out Ventilation of Houses for a more indepth look at this issue.
http://irc.nrc-cnrc.gc.ca/pubs/bsi/83-4_e.html
