F6D7 requires that permanent openings, windows, doors or other openable means provide natural ventilation. It also deals with the size of such openings, and the locations to which such openings must open.

F6D7(1)(b)(i) requires a judgement regarding what is “suitably sized”; and F6D7(1)(b)(ii) requires a judgement regarding what is “open”.

F6D7 does not require any of the required natural ventilation to be “fixed ventilation” or “permanent openings” as against “devices which can be opened”. The building proponent can make the decision.

If the natural ventilation openings are used only for ventilation purposes, roller shutters and doors can cover the openings if they achieve the performance standard in F6D7(1). However, if the openings are also used for egress purposes, they must comply with the requirements of provisions such as D3D24 and D3D26.

Under F6D7(2), the option of using prescribed natural ventilation opening sizes for Class 8 electricity network substations is removed. The prescribed ventilation openings are not conducive to Class 8 electricity network substations as they may allow excessive dust, humidity and other weather conditions that are detrimental to the sensitive and hazardous equipment used in these buildings.