Associating occupants' interaction with windows with air change rate --One case study

Air change rate (ACR) significantly influences the indoor thermal environment and indoor air quality. Moreover, as a matter of fact, ACR varies with time during natural ventilation. However, to date only a few studies have accounted for the dynamic ACR for the actual in-use buildings. To address this issue, a field measurement of outdoor/indoor environments and the window state was conducted in a dormitory in Beijing in spring, summer, and autumn. Transient Mass Balance Equation (TMBE) method associated with the extended Kalman filter (Hereinafter referred to as Kalman filter method) was adopted to obtain the dynamic results of the ACR. Then the correlations of outdoor/indoor environments with the ACR and the probability of window opening were investigated. The results confirm the validity of Kalman filter method for tracking the dynamic nature of natural ventilation in residential units, and further demonstrate that occupants' interaction with windows does not simply refer to opening/closing windows, but also refer to adjusting the extent of the window being open in response to occupants' ventilation needs. Therefore, in addition to the probability of window opening, ventilation needs, i.e., the dynamic ACR, as the underlying trigger for window opening behavior, should be used as an indispensable part of describing occupants' interaction with windows. This study provides a complete framework to describe occupants’ interactions with windows by combining the dynamic ACR and the probability of window opening.