Air tightness is a very important part of an efficient, low carbon home. You can have the best insulation in the world, but if the warm air is blowing out through cracks and gaps in the fabric of the building, you’re not going to see those benefits.
Equally, ventilation is a very important part of a fresh, comfortable home. Good ventilation allows stale air from in the home to be exchanged with fresh, clean air from the outside. It allows odours and gases such as carbon monoxide and volatile organic compounds to escape into the atmosphere and it removes moisture from the air. Moisture is created through normal household activities such as cooking, washing and drying and it is critical that it is removed from the home so as to avoid condensation and damp.
The trick is to achieve the correct amount of controlled, desirable ventilation that allows the air in the home to be exchanged with fresh air from outside, while reducing the uncontrolled and undesirable draughts.
You can measure the rate at which air leaks from a home by conducting an air permeability test. This involves blocking all of the vents up, closing windows and doors and generally sealing off all of the controlled ventilation routes. A screen fitted with a powerful fan is then placed over the door and the air pressure within the home is increased. By measuring how much power is required to maintain this pressure, you can calculate the air leakage rate.
Knowing the rate at which the air escapes through gaps and cracks is all well and good, but really you want to know where it’s escaping so that you can do something about it. Often you can tell that there’s a draught in a room but it’s not possible to work out where. During the pressure test someone walks around the home with a smoke generator, checking likely areas to see if there is a draught – the smoke will follow the air through any crack and out of the home.
Draughts can occur all over the home – gaps between suspended timber floorboards, around skirting boards and electrical fittings, at the join between walls and the join between floors and walls, around pipework penetrating the fabric, around loft hatches, up chimney, through letter boxes and keyholes and of course around doors and windows.
The next post on draught proofing will cover the quick and easy measures you can take to start improving the air tightness of your home – it’s cheap, easy, DIY and well worth doing.
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I was wondering some time ago what has happened to the contacts and equipment from the ‘Green Homes Concierge’ project that I think is now defunct.
The local traders and stockists info would be very useful as a basis for other local directories etc.
Also wondering if the local councils could do a subsidy deal with hire shops like HSS to hire out air tightness things discussed above, cheaply to householders or local community groups.
The website is still up but I’ve not heard from them in a while (I used to offer bits and bobs of support to them from time to time).
By air tightness things do you mean the pressure testing kit? I like the idea of HSS getting involved although it does take some specialist training to do it right.
There is a great old book called ‘keeping warm for half the cost’ by John Colesby and Phil Townsend that has really simple line drawings that cover different things like draughtproofing, secondary glazing, cold bridges etc. Delightfully simple and an easy read. Can be got on ebay for about 3 of 4 quid or via http://www.thebookdepository.co.uk in their second hand section similar price.
Best thing I have seen to identify different draughtproofing methods/materials.
Have just noticed on http://www.projectdirt.com that Sue Sheehan (london leader, started Hyde Farm Energy Action Network and the London Low Carbon Communities Network) has put some docs up on running ‘Draughtbusting Saturday’ (these have been going a couple of years south of the river).
Here is the link: http://www.projectdirt.com/group/LondonLCCN/forum/topics/how-to-organise-a
N.B AJ Mconville has added a note there saying he is interested, he is Transition Highbury so just across the park from Stokey.
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