Performance assessment of residential demand controlled exhaust ventilation strategies

Contemporary building practise is searching for concepts and technological innovations that will allow to maintain or improve the comfort level that is currently reached while reducing the energy consumption that is related to it. Ventilation is ambiguously related with this energy saving rationale. Since it makes up for about half of the energy consumption in well insulated building, it is an attractive target for energy saving measures. However, simply reducing ventilation rates has unwanted repercussions on the indoor air quality. This paper focuses on the energy saving potential of demand controlled mechanical exhaust ventilation in residences and on the influence such systems may have on the indoor air quality. 4 approaches to demand based control are tested with multi-zone airflow simulations of a statistically representative detached dwelling. Both energy demand and exposures are reported in comparison with a building code compliant continuous flow rate system. Within the paper exposure to carbon dioxide and to humidity are used as indoor air quality indicators. The robustness of the systems is tested using Monte-Carlo techniques. Under the applied conditions, the demand control systems rendered ventilation heat loss reductions of 25 to 60%, depending on the control strategy that is implemented