Open or Closed? Use of Windows and Doors at Home: Ventilation Rates in Occupied Dwellings

Ventilation in dwellings is likely to be impacted by configurations of windows and internal doors, but there is little empirical research investigating this in occupied homes. Closure of internal doors will affect noise, light, heat flow and how air moves into and through a building, as well as the volume of air in which pollutants are diluted. However, most ventilation measurements in homes have either conducted long-term averages in which the effect of use of windows and doors is not addressed, or small numbers of ‘snap-shot’ measurements in which the distribution of ventilation rates in particular configurations is not known; this reduces our understanding of environmental quality at home.
This paper reports the detailed investigation of window and internal door use and their link to ventilation measurements in two occupied flats in the same building over six months. Doors and windows were monitored using event-logging contact sensors and CO2 was measured in all rooms. An algorithm for determining occupied periods was used and ventilation rates were estimated using the CO2 decay technique during unoccupied times. In one of the flats almost 70% of the ventilation measurements were less than 0.5 ach in the configuration in which the occupant spends 55% of their time while at home; in the other flat windows were open for 80% of the occupied time and 90% of the ventilation rates measured with windows open were above 0.5 ach. The dwellings were physically similar, equipped with the same ventilation equipment and subject to the same weather. These results highlight the importance of considering the extent to which conditions during measurement periods (or modelled conditions) reflect the conditions that occupants experience.
Further research employing methods able to characterize ventilation in homes and distinguish between occupied and unoccupied times, contextualized by measuring configurations of doors and windows, will support greater understanding of ventilation in dwellings. This could provide insights into the real conditions in homes, supporting effecive modelling and design. Such detailed research would support developments in practice and policymaking, by helping to disentangle the related issues of ventilation rates, indoor pollution, personal exposure to pollutants and the effects of these on health outcomes.