Why focus on mould, ventilation and health when thermally upgrading a house? Here are two of many reasons:
· Our population has the fourth highest incidence of asthma in the world and allergies are rising fast. Alarmingly things may be getting worse: recently the World Health Organisation has found that as many as third of Irish children now have asthma.
· Studies in other countries have found a close correlation between these diseases and the environments we spend so much of our time in: homes, offices and schools. In one study of 328 homes in southeast France, selected because residents had been admitted to hospital sick, Dr. André Charpin  and his colleagues found mould infestation in 44%, mite contamination in 32% and volatile organic compound (VOC) exposure in 9% of the homes.
The issue of houses contributing to the ill-health of their occupants is not to do with ‘airtight’ houses as some lobbies would say. We still probably have less than a hundred living units in the country where air infiltration has been reduced to 3 m³/m²h. The issue is hundreds of thousands of semi-leakyhouses with no managed ventilation system, and little focus on moisture movement and the chemical constituents of building materials and furnishings. Ironically the houses of our great-grandparents which had gales blowing through them, roaring fires (giving good radiant heat) and a small range of natural building materials were healthier places than those we’ve been building for the last thirty years.
In contrast a well-insulated house with very low air infiltration (i.e. air leakage), good orientation and natural light, a well-design managed ventilation system, perhaps a radiant source of heat and a well-thought out palette of natural materials must be a healthy, healing place to live… as well as very energy efficient.
 Charpin-Kadouch, C., Charpin, D.A., et al (2006) ‘Housing and health counselling: Preliminary results of a new medical referral system in France’, Environmental Research