Avoiding condensation from fixing draughts

I mentioned recently I have been running some new workshops on promoting energy saving projects in buildings. This is interesting work because different issues come up every time - one which was of concern recently is condensation in our increasingly air tight houses. Though it is hard to get that air tight in an old house, it is possible if you do enough draught fixing. Even sleeping we breath out moisture though the main sources of moisture indoors are cooking, bathing and laundry.

There are a range of options for managing this moisture without losing unnecessary heat: including opening the windows, fitting trickle vents and extractor fans, humidity controlled vents or, if your budget allows, whole house ducted ventilation with heat recovery. The latter also helps people with allergy problems since the incoming air is filtered.


I touched on this subject recently after a trip to Ecobuild in 'How much ventilation do you need?' but this was mainly about ducted ventilation systems. I have put together a more comprehensive advice page on the Transition Cambridge website which discusses all aspects of the problem - fixing the draughts, understanding condensation problems areas and the various different ways to manage ventilation Do take a look at it and tell me if you find it helpful.

By the way it is also possible to get extractor fans with heat recovery that fit in a wall and ventilate a single room. However, a whole house ventilation and heat recovery system should be able to recover at least 85% of the heat in the air going out and the product description will indicate clearly what you can expect. A single room heat recovery fan is likely to be less effective simply because there is less space for the heat exchanger and if you can't find any specific claim for the efficiency of a product I should assume the worst. I have found products from KAIR and Nuaire that claim up to 86% efficiency. However, they cost upwards of £300, which is approaching the price of the heat exchanger bit of a whole house unit (not including ducting and fitting).