Indoor air quality in naturally ventilated dwellings in Spain

This article presents the results of the exploratory study on indoor air quality in existing dwellings with traditional ventilation systems based on natural ventilation. A preliminary study of the most representative typology of the Spanish housing stock has been conducted and, based on it, twelve dwellings located in Madrid have been monitored in different periods. Monitored indoor air quality has been compared to that required in the regulations in Spain, the Código Técnico de la Edificación (Technical Building Code). According to the results of the research, 50 % of the monitored dwellings do not comply with the CO2-based air quality quantification offset in the regulations. Such non-compliance is primarily caused by high CO2 concentrations in winter, especially in bedrooms. These high concentrations and their seasonality are attributed to the interference of the occupant’s behaviour, influenced by weather conditions, that is affecting the efficiency of the existing natural ventilation systems.