Radon as an indoor pollutant can be overlooked – it is colourless and odourless, and you cannot tell if a building is at risk of high radon levels just by looking at it.
Yet radon is a carcinogen, and is responsible for more lung cancer than anything else except tobacco smoke.
Because Passivhaus sets such meticulous store by airtightness and good ventilation, it is perhaps not surprising to learn that Passivhaus buildings tend to have much lower radon levels than non-Passivhaus buildings in the same location.
While building a Passivhaus definitely doesn’t substitute for the specific radon protection measures appropriate to your location, the research shows building or retrofitting to the Passivhaus/Enerphit standard can markedly supplement these protections. Findings from Ireland and elsewhere in Europe have demonstrated this clearly, as I discuss in this article for Passive House Plus magazine.