Indoor air quality in the news and blogosphere - what's the answer?
The Guardian and Sustainable Homes blog have both recently published pieces about indoor air quality and energy efficiency. Both articles highlight that increased energy efficiency is linked with poorer indoor air quality which is associated with health problems, particularly asthma. The issue arises as more energy efficient buildings are designed and constructed with higher levels of air tightness. This means that air cannot leak through cracks and gaps in the building fabric to refresh the internal air with air from outside.
However, the air we breathe and the fresh air which flushes out contaminants from your house are not supposed to be replaced by flow through gaps in the fabric, the fresh air is supposed to be drawin in through background ventilators, usually trickle vents in windows, by extract fans in kitchens and bathrooms. The problem is that the trickle vents are often not sufficiently large and the extract fans are set on low speeds to avoid noise. With increasing airtightness the gaps in the building are not there to provide a safety net. There is also a problem when the fans are off, when wet rooms are not in use.
One answer is to use continuous fans which run quietly and continuously at a background speed and then increase the speed to purge ventilate when bathrooms and kitchens are in use. This can provide sufficient ventilation, but it also purges heat from the builidng.
The best solution - well designed, high quality, silent, heat recovery ventilation (HRV) - such as this unit at Toronto Road, Bristol. Come and see it on Saturday 26 September when it is open for Bristol Green Doors.
Ventive is an innovative alternative which can be installed in chimneys as part of a refurbishment, with less disruption than full HRV.



