An independent air quality report, funded by the UK Technology Strategy Board, currently in draft format but soon to be published on the bere:architects research pages, has produced some striking evidence for the ability of properly designed, properly installed and properly commissioned heat recovery ventilation to significantly improve indoor air quality, particularly in urban locations.

The report comprehensively examines air quality in our London Passive House at 4 Ranulf Road, and compares this with the air quality in a conventional London house, also in Ranulf Road. It also measures air quality in our two Welsh Passive Houses at Ebbw Vale.

I’ve had a first skim through the draft air quality report and one thing that jumped out at me from the reported data was the PM10 and PM2.5 particulate data. These particulates come mostly from vehicles and there is growing evidence that they are a cause of lung cancer, heart attacks, strokes and asthma.

As reported by Clean Air London: “The Mayor published a study in 2010 estimating 4,267 premature deaths in London in 2008 attributable to long term exposure to fine particles (PM2.5).  These occur mostly as heart attacks and strokes.  The Department of Health estimates 6.3% to 9.0% of all deaths in London in 2010 were attributable to long-term exposure to man-made PM2.5 alone.”

  1. The data contained in the report enabled me to compare the Certified Passive House in London with a conventional house a hundred metres along the same road. The level of particulates inside the Passive House is up to four times better than the conventional house! That is when comparing master bedrooms. Or three times better when comparing living rooms.
  2. Indeed the average particulates count inside the London Passive House was equal to, or sometimes significantly lower in particulates (by up to a third) than the average outdoor air in a relatively rural location in the Welsh hills (although as someone has pointed out, there may be residue from the area's industrial past). However, the average outdoor level of PM10 & PM2.5 particles in London, was measured to be over twice as bad as Ebbw Vale in Wales (with just one day between the measurements, and unchanged, cold, March weather conditions in both locations, 4°C in London and 3°C in the Welsh hills of Ebbw Vale).
  3. It is also worth noting that the Passive House at 4 Ranulf Road was found to have an average particulates count indoors more than three times better than  the average count of the external air.


This is yet further solid evidence of the health-enhancing benefits of a Passive House, and firm evidence of the health-enhancing potential of properly designed and installed heat recovery ventilation systems (in the UK sometimes referred to by the ugly description of MVHR).

Thanks to Alan Clarke and Andrew Farr for their very professional design, installation inspections and commissioning of the heat recovery ventilation system at the 4 Ranulf Road, 'Camden Passivhaus'.