Poor air quality threatens health in energy efficient homes, say researchers

Research monitoring the performance of 20 new-build housing association homes built to Code for Sustainable Homes levels 3 and 4 has found that 19 experienced inadequate ventilation leading to poor indoor air quality.

The research, by Cartwright Pickard Architects and the Mackintosh Environmental Architectural Research Unit (MEARU) at Glasgow School of Art, found that the affordable homes "built by London’s biggest contractors for well-known housing associations" had been designed with high levels of airtightness and were therefore reliant on poorly commissioned or inadequate ventilation systems.

The research project was funded by Innovate UK, and the results were published in The Architects’ Journal. A full report is due to be published later this year. 

Researchers monitored the 20 properties in Poplar, Colindale, Acton and Aldershot for three, two-week periods – in summer, winter and mid-season – to determine how well each house was performing in different conditions.

The study concentrated on health and wellbeing, rather than energy efficiency.

Internal CO2 levels were recorded at levels above 1,000ppm (parts per million) – the maximum allowable level for a “good fresh air supply” according to the research – at 19 of the 20 properties.

Although CO2 concentrations would need to be above 4,000ppm to be directly harmful to humans, anything above 1,000pm is seen as an indicator of poor air quality and ventilation.

The highest levels of CO2 were recorded in the winter, when concentrations above the recommended level of 1,000ppm were recorded during 54% of the housing’s occupied hours, with sustained levels over 2,000ppm and peaks of 3,250ppm recorded.

The research identified “badly installed and incorrectly commissioned” ventilation systems, with particular concerns raised by mechanical ventilation heat recovery (MVHR) units. The majority of the MVHR systems tested failed to meet the Building Regulations’ advisory airflow rates.

The units were often found with air filters that had not been changed or cleaned, contributing to high levels of CO2. Trickle vents above windows were also found to be either non-existent, closed or covered by curtains or blinds, further reducing the flow of fresh air.

In summer, excessive solar gain from unprotected full-height windows, along with underperforming ventilation systems and MVHR systems with non-functioning summer bypass functions, contributed to overheating.

The authors urge a reinvestigation of MVHR systems because of installation and maintenance issues, along with their cost, complexity, and the fact that users were not being able to correctly operate their systems.

“There are simpler and more practical alternative mechanical ventilation systems on the market, which do not require filters and that can respond to occupational density and varying conditions within each room or dwelling,” the report states.

According to the research team, a trend to “mandated complication” is leading to complicated design and specificaton “even though building performance feedback suggests that it is difficult to to get even the simple things right”.

The report continued: “This has set the industry on a path to unintended health consequences, with problems caused by, for example inadequate ventilation, evaoprtation of volatile chemicals into the air, and reduced standards of space and light. 

“The resulting health risks are both physiological (respiratory disease, diminished immune system, diabetes, obesity) and pyschological (seasonal affective disorder, depression).”

It also suggested a possible link between poor air-quality levels in UK properties and rising levels of asthma in the country. 

Cartwright Pickard will be presenting the detailed findings of the research during a half-day seminar with the theme “Health and Wellbeing in New Homes” at the British Library on 19 November.