Contents lists available at ScienceDirect Sustainable Cities and Society journal homepage: www.elsevier.com/locate/scs Effects of buildings’ refurbishment on indoor air quality. Results of a wide survey on radon concentrations before and after energy retrofit interventions Luca Pampuri a , Paola Caputo b, ⁎ , Claudio Valsangiacomo a a Radon Competence Centre, University of Applied Sciences and Arts of Southern Switzerland (SUPSI), Campus Trevano, CH-6952 Canobbio, Switzerland b Architecture, Built Environment and Construction Engineering Department, Politecnico di Milano, Via Bonardi 9, 20133 Milano, Italy ARTICLE INFO Keywords: Radon protection Buildings retrofitting Radon measures Statistic analysis Ventilation systems Indoor air quality ABSTRACT 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 interven- tions 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. 1. Introduction Energy saving measures within the built environment (e.g. energy retrofit of existing buildings) represent an important institutional strategy of governments committed to the need to decrease fossil fuels utilization in the implementation of climate change national policies. Several programs and regulations at global and local level document this issue. However, since energy saving and indoor air quality (IAQ) are the two sides of the same coins, the impacts of the interventions have to be evaluated both in terms of energy performance improvement and in terms of indoor comfort preservation. Energy saving should be accomplished by proper measures in order to guarantee also healthy IAQ. When energy retrofit is improperly implemented, it can worsen IAQ, especially if energy saving measures are not accompanied by ap- propriate means of air exchanger between indoors and outdoors. Doors and windows that are not hermetically sealed can contribute to air change per hour (ACH) in a significant way. Because energy saving measures normally change the permeability of the building envelope and consequently decrease the ventilation rate, it is important to carefully evaluate this issue before energy retrofit is undertaken. Regarding IAQ, many aspects and parameters can be considered; the research here presented focus on radon concentration. Radon has an enormous impact on the health of the occupants, being the second cause of lung cancer after smoke according to the World Health Organization. The dramatic effects of exposure to radon on human health are well known and documented (World Health Organization (WHO, 2009). According to a recent study (Milner et al., 2014), the effect of energy retrofit can increase the exposure to radon and risk of lung cancer. The implications of energy retrofit in terms of possible decrease of ACH “need to be carefully evaluated to ensure that the desirable health and environmental benefits of home energy efficiency are not compromised by avoidable negative impacts on indoor air quality”. For example, in Switzerland, where the problem is more serious than in other European countries (Vienneau et al., 2017), attention is payed to radon measurements and mitigation in homes and dwelling (Federal Office of Public Health (FOPH, 2011) and three official radon competence centers have been operating since 2008 in the different linguistic areas of the country, including the Italian part (see also: Centro Competenze Radon – CCR Radon Competence Centre). The Swiss https://doi.org/10.1016/j.scs.2018.07.007 Received 20 April 2018; Received in revised form 12 July 2018; Accepted 12 July 2018 ⁎ Corresponding author. E-mail address: paola.caputo@polimi.it (P. Caputo). Sustainable Cities and Society 42 (2018) 100–106 2210-6707/ © 2018 Elsevier Ltd. All rights reserved. T