Short-term mechanical ventilation of air-conditioned residential buildings: A general design framework and guidelines

Ventilation is needed in air-conditioned residential buildings, particularly the bedrooms in nighttime sleeping periods, to maintain an acceptable indoor air quality. Our previous on-site measurements evaluating various ventilation strategies suggest that short-term mechanical ventilation is overall the most appropriate ventilation strategy for air-conditioned residential buildings. However, there is still no a general design framework of short-term mechanical ventilation strategy, which can determine appropriate design parameters, including ventilation period, ventilation frequency, and start concentration of ventilation, based on various combinations of indoor CO 2 generation rate, net room volume, infiltration rate, and mechanical ventilation rate. This study for the first time develops such a design framework and then provides the detailed design guidelines. A whole sleeping period of 8 h is divided into many repeated single V -shape ventilation periods; each single ventilation period is comprised of a short-term mechanical ventilation period and a follow-up CO 2 build-up period. The single V -shape ventilation process is particularly investigated based on a criterion that the average indoor CO 2 concentration is less than but close to 1000 ppm. A high efficient ventilation strategy, namely requiring a minimum total mechanical ventilation period, is a short single ventilation period and a high ventilation frequency. The outcomes of this study are presented in the form of figures and tables, with most parameters normalized, which are useful to assist a rapid ventilation design.