The updated NCC 2022 10.8.2 regulations cover exhaust fans and range hoods. They for part of the Condensation Management provisions that are designed to reduce the problem of excess moisture from buildings.
The regulations specify minimum flow rates for indoor spaces with high moisture levels. The minimum flow rates for these spaces are as follows:
• Bathrooms & Sanitary Compartments: 90 m³/hr (25 L/s)
• Kitchens & Laundries: 144 m³/hr (40 L/s)
If a bathroom or sanitary compartment lacks natural ventilation, the exhaust fan must be interlocked with the room’s light switch and feature a ten-minute run-on timer that runs after the light switch is turned off. This can be completed with a fan with a built-in run on timer – or a run on timer can be wired into a non-timer fan by a licensed electrician. It is generally simpler to use a fan with a built-in run-on timer.
Quoted flow rates of all fans are always based on laboratory conditions and will all perform at a lower flow rate when ducted in a house. Therefore we recommend selecting a fan that has a flow rate well over the prescribed minimum. We have developed models both with and without run-on timers. Alpine Ventilation exhaust fans have powerful Japanese bearing motors that achieve significantly higher flowrates than the minimums required under NCC guidelines. Check out Alpine Ventilation exhaust fan range on our site.
Previously many builders vented fans into the roof cavity and just used several non-ducted rotary roof vents to ventilate the roof cavity. This is no longer allowable.
The new NCC regulations specify that range hoods and exhaust fans must vent directly to outdoor air via ducted vents. This requires that ducted roof, fascia, eave or fascia vents must be used often in combination. Alpine has a series of options for all of these types of vents. Insulated ducting is not required. Builders have the option of using either non-insulated semi rigid ducting or flexible foil ducting. Semi rigid ducting is more efficient however flexible ducting is more robust and easier to install.