A Longitudinal Study to Assess Indoor Environmental Quality in Airtight Energy-Efficient Naturally Ventilated Dwellings

The global demand to improve the energy performance of buildings has led to greater air tightness and uncertainty in the ability of natural ventilation to maintain adequate indoor environmental quality. A monitoring campaign was carried out to evaluate the long-term indoor environmental quality across a year-long period in energy-efficient Irish dwellings. During the winter months (December, January, February), the mean PM2.5 concentration in kitchens was 19 µg/m³, which is 38% higher compared to the summer months (June, July, August), where the mean concentration was 13 µg/m³. The mean PM2.5 increased 58% in winter (19 µg/m³) than in summer (12 µg/m³). In bedrooms, the mean CO2 concentration during winter was 1116 ppm, reflecting a 19% increase over the summer concentration of 919 ppm. In the living room, CO2 increased 29% in winter from summer. Additionally, radon levels in the dwellings were 52% higher in winter than in summer; however, they remained well below the Irish EPA threshold of 200 Bq/m³. VOC mean values in winter and summer showed similar ranges across the monitored dwellings, referring to the greater impact of occupancy activities than ventilation.