Buildings Guide

Natural Ventilation  »  Mixed-mode ventilation


During extreme weather and climate conditions, natural ventilation system only may not be suitable. Mixed mode ventilation with the combination of natural and mechanical ventilation is required. Such as in the absence of required wind flow in the room during hot summer days, the installation of exhaust fans in the path along with operable windows increases natural airflow and brings ambient indoor environment. In mixed mode ventilation, the control strategies such as opening the windows can be both automated or individually controlled by the occupants (Kleiven, 2003). The number of exhaust fans and their size depends on the required level of ventilation rate (WHO, 2009). In general, mixed mode ventilation is quite effective in achieving good indoor air quality, thermal comfort, energy savings and user satisfaction.


Mixed mode ventilation is one of the baseline requirements in all the building energy codes as an effective passive strategy, both for energy savings and cost reduction.

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