This feature was commissioned by the monthly journal of the Royal Institute of British Architects (RIBA). It provided an authoritative statement of some of the latest research on air quality in homes, with a particular focus on the high standards achieved in Certified Passive House (Passivhaus) homes in the UK.

Bere:architect's Larch House in Wales was used as a case study. Humidity from indoor clothes drying during winter months was found to be quickly eliminated by heat recovery ventilation and optimal conditions were found at all other times too.

In bere:architect's Camden Passive House, a particulates test was carried out to compare the Passive House with an ordinary house in the same street. It was found on the day of testing that far fewer harmful PM2.5 particulates were found in the Passive House than in the ordinary house. It is thought that this may be due to the fine F7 / F8 grade filters fitted on the intake of the ventilation unit of the Passive House and the air-tight seals of the windows and doors that do not allow the toxic particles to penetrate the house. By contrast, the window frames of the ordinary house allow the infiltration of particulates which build up to form a black, sooty film around the inside of the windows unless they are regularly wiped clean.