Problems associated with inadequate Ventilation

Over time, stale air, dampness and condensation all contribute to the deterioration of buildings, causing unpleasant, uncomfortable and unhealthy living conditions.

Stale air is caused by inadequate ventilation and often made worse by humidity, steam, smoking, cooking and, of course, odours remaining in toilets and bathrooms. The result is a room that feels dank and uninviting. Condensation occurs when moist warm air comes into contact with a cooler surface such as walls, ceilings and windows. This often leads to mould growth, peeling wallpaper, damage to painted surfaces or even more serious structural damage such as timber decay. These problems are a result of poor ventilation but can be resolved through the correct selection and installation of a high quality fan.

NCC Regulations for Bathroom & Toilet Ventilation

Clause F6D6 of the National Construction Code:
A habitable room, office, shop, factory, workroom, sanitary compartment, bathroom, shower room, laundry and any other room occupied by a person for any purpose must have—
(a) natural ventilation complying with F6D7; or
(b) a mechanical ventilation or air-conditioning system complying with AS 1668.2 and AS/NZS 3666.1.

Clause F6D7 of the National Construction Code:
Natural ventilation provided in accordance with F6D6(a) must consist of openings, windows, doors or other devices which can be opened—
(a) with a ventilating area not less than 5% of the floor area of the room required to be ventilated; and
(b) open to—
(i) a suitably sized court, or space open to the sky; or
(ii) an open verandah, carport, or the like; or
(iii) an adjoining room in accordance with F6D8.

Clause F8D4 of the National Construction Code (NCC):
(1) An Exhaust System installed in a kitchen, bathroom, sanitary compartment or laundry must have a minimum flow rate of –
(a) 25 L/s for a bathroom or sanitary compartment; and
(b) 40 L/s for a kitchen or laundry
(2) Exhaust from a kitchen, kitchen range hood, bathroom, sanitary compartment or laundry must discharge directly or via a shaft or duct to outdoor air.
(5) An exhaust system that is not run continuously and is serving a bathroom or sanitary compartment that is not ventilated in accordance with F6D7 must—
(a) be interlocked with the room’s light switch; and
(b) include a run-on timer so that the exhaust system continues to operate for 10 minutes after the light switch is turned off.

RECOMMENDED SYSTEM DESIGN

Exhaust

To effectively exhaust water vapour (steam) from a shower, air flows of 270 to 360m³/hr (75-100L/s) are required, depending on climatic conditions and room size.

Make-Up Air

What goes out, must come back in. Adequate make up air should be allowed to enter the room to replace the air exhausted by the fan. This can come in the form of an open window, a door undercut, or a vent to an adjoining room. Without adequate make-up air, any installed fan will not be able to perform as designed.