In comparison to building energy performance, assessment of the impact of energy upgrades on indoor air quality and occupant comfort has received little attention.

Concentrations of indoor air pollutants in fifteen, three bed semi-detached co-operative social dwellings were monitored before and after an energy upgrade during the winter periods of 2015 and 2016. The fifteen dwellings consisted of seven cavity wall (CW) dwellings and eight hollow block (HB) wall dwellings. Concentrations of indoor air pollutants including CO, PM2.5, CO2, TVOCs, formaldehyde, BTEX, NO2 and thermal parameters including temperature and relative humidity, were measured in the main living area and main bedroom before and after the energy upgrade.

Building air tightness decreased from pre retrofit values of 9.26–10.00m3/(h.m2) @ 50 Pato an average of 5.53 m3/(h.m2) @ 50 Pa and 8.61m3/(h.m2) @ 50 Pa post retrofit (CW group and HB group, respectively). Concentrations of CO2, TVOC, and PM2.5 significantly changed post-retrofit, increasing post retrofit in both dwelling groups (CW; p = 0.014; p = 0.009; p = 0.005) (HB; p = 0.003; p = 0.032; p = 0.008). Increases in pollutant concentrations were correlated with lower building air exchange rates post retrofit. This study suggests that the energy retrofit had a positive impact on occupant comfort and building temperature; however, concentrations of some pollutants were found to increase following the retrofit.

The study highlights the importance of characterising indoor air quality post energy retrofits within the overall building energy performance to ensure improved health outcomes for building occupants post retrofit.