Building drier, healthier homes

Good ventilation is key to ensuring the home you build for your clients is one they can be happy and healthy in.

On average, New Zealanders spend 75% or more of their time at home – yet surveys of New Zealand homes show they are cold and damp, the perfect conditions for mould, which thrives in humidity greater than 70%. 

A dry home is all about ventilation, stopping moisture getting in and removing the sources of moisture.

Much of a home’s ventilation depends on its design – how it is oriented and the number and placement of windows.

If you’re the owner’s first point of contact,ensure they’re aware of the importance of ventilation; if the design doesn’t call for it, ask the designer why it’s missing.

Considerable moisture is generated by simple household activities. A shower, for example, can produce 1.5 litres each time it’s used. This moisture evaporates into the air and, if not removed, can contribute to condensation and mould.

The most significant sources of moisture in a home come from the kitchen, bathroom and laundry. All these rooms should have mechanical extract ventilation (extractor fans or range hoods) to remove moisture.

Ensure you vent to the outside and not into the roof space, as that will allow moisture to accumulate and damage the insulation and internal roof structures.

Range hoods should extract to the outside, rather than recycling air, as recycling simply removes food smells but not the moisture from cooking.

Extract ventilation is so straightforward that it’s often not top of mind when thinking of home performance.

A dry home is all about ventilation, stopping moisture getting in and removing the sources of moisture

However, providing your clients with effective means to extract moist air from their home is a simple way you can contribute to their health and enjoyment in years to come. 

Tips for effective extractor fans and range hoods:

• Choose the right-sized fan for the job. A fan that’s too small won’t remove enough moist air to keep the home dry. A fan that’s too large can create draughts. Minimum requirements for extractor fan performance are set down under the Building Code.
• Install models with automatic controls, such as a timer, which runs for ten minutes after it is turned off.
• Combined light/extract units are often not very effective ventilators, as the light unit usually reduces the extract rate – select separate units.
• Locate the extract inlet as close as possible to the moisture source – for example, close to the shower if it’s in a bathroom.
• Locate the outlet vent away from windows – otherwise the moist air will just blow back in if the window is open.
• Pay attention to the ducting – straight ducting is much more effective than ducting which has kinks or goes around a corner
• Ensure the weather grill shuts properly, so that there isn’t too much heat loss when the fan’s not in use.
• With range hoods, it’s important that the hood covers the whole stove – and isn’t too far away from the elements. If it’s a smaller size than the stove, or very high above the elements, then it won’t work.

About Beacon Pathway

Beacon Pathway is a group committed to transforming New Zealand’s homes and neighbourhoods through research and demonstration projects that show how to make homes more resource efficient, healthier to live in, adaptable, resilient and affordable. For further information about
Beacon Pathway visit www.beaconpathway.co.nz