Enviropass, which carries out air quality assessments for planning applications across London and the UK, is raising concerns about where low carbon homes get their fresh air from.
New low carbon homes are built to be well insulated and airtight. That keeps the heat in and carbon emissions down, but it also means fresh air no longer finds its way in through gaps in the building. Residents rely instead on mechanical ventilation, which pulls outside air in through an intake. If that intake is on the side of the building facing a busy road, the air going into people’s homes could be problematic.
Enviropass is clear that this is not an argument against net zero. Replacing gas boilers with heat pumps takes a significant source of pollution off London’s streets. In the City of London, gas boilers heating commercial buildings are the largest single source of nitrogen oxide emissions. The concern is the air these sealed buildings take in.
“It’s a bit like a snorkel,” said Matthew, a Director at Enviropass. “An airtight building breathes through its ventilation intake. Net zero and clean air should work together, but that only happens if someone asks where the air is coming from before the building is designed.”
Enviropass says its air quality assessments regularly show big differences in pollution levels across a single site, with a facade on a main road often facing much poorer air than one overlooking a courtyard or a quieter street.
The company recognises that many mechanical ventilation with heat recovery systems include filters, but stresses that where the intake goes still matters and needs thinking about from the start.
There is also a clash with overheating policy. London planners increasingly want buildings to stay cool through passive measures such as natural ventilation. On a busy road, though, opening the windows to cool a flat can let the pollution in. Enviropass says carbon, overheating and air quality are often looked at separately, by different people at different stages, even though each one affects the others.
An air quality assessment for planning is a technical report submitted with a planning application. It assess whether a development will make local air quality worse, and whether the people who will live or work there will be exposed to unacceptable pollution. In London, the London Plan expects all new development to be at least Air Quality Neutral, and councils typically require an air quality assessment for sites in an Air Quality Management Area, which covers much of the capital. Assessments follow guidance from the Institute of Air Quality Management (IAQM).
“By the time a scheme reaches us, the building is designed and the intake is fixed,” the spokesperson added. “The positions of the air intakes are the responsibility of the architect and developer at the design stage. They need to consider this from the very beginning.”
With hundreds of thousands of new homes planned for London over the coming years, many of them built to airtight, low carbon standards, Enviropass expects the problem to grow. It is urging developers and architects to look at local air quality early in the design process, well before a planning application goes in.
ENDS
Distributed by Pressat
Additional Contact(s):
Matthew Colley
