Effects of buildings’ refurbishment on indoor air quality. Results of a wide survey on radon concentrations before and after energy retrofit interventions

Energy regulation, policy and targets enhance energy retrofit in buildings with a wide distribution in Europe and Switzerland. These actions are mainly aimed at reducing heat dispersion through the envelope. The interventions affect the permeability of the envelope influencing indoor air quality. Focusing on radon concentration, this study reports the results of a survey on 154 buildings measuring the radon concentrations before and after energy remediation. The buildings were located in the southern part of Switzerland (Canton Ticino), a region with measurements of radon concentration in more than half of the buildings (over 55,000 building in 2018), within a population of approximately 355,000. These figures make this region an area with an exceptionally high number of radon measurements, performed in 2005–10 upon mandate of the local public health authorities. The survey reveals the increasing of radon concentrations, in particular where windows were replaced with more performant ones. Results underline the need of considering energy saving and indoor air quality at the same time, in the frameworks of orienting public and private investment towards improving long-term public health. Adequate techniques for improving ventilation could be very helpful to that end.