DISCUSSING THE NEW ZEALAND BUILDING CODE...
Victoria Mitchell: STATEMENT HOMES
Fresh Air, Healthy Homes:
Why Ventilation Must Be in the Building Code
In my view, New Zealand has overlooked one of the simplest, most powerful changes we could make to improve the quality of our homes. We often talk about insulation and double glazing as the keys to warm, dry, healthy living, but there’s a missing piece that makes just as much difference – ventilation.
At present, the Building Code still assumes ventilation is achieved by opening windows equal to five percent of the floor area. On paper, that seems reasonable. In reality, it doesn’t work. We shut our windows in winter to keep warm, we avoid opening them near busy roads because of noise and pollution, and many people simply don’t open them often enough. The result is predictable: moisture and stale air build up inside, condensation runs down walls and windows, mould grows in bedrooms and bathrooms, bugs and dust mites thrive, and families get sick more often with asthma, colds, and respiratory illness. This is not just about comfort, it’s about the health of our people and the durability of our homes.
I know this first-hand. As someone with asthma, I’ve experienced how much harder it is to stay well in a damp, stuffy house. The difference after moving into a home with a proper ventilation system was life-changing. Fewer flare-ups, easier breathing, and a healthier environment overall.
The frustrating part is that the fix is obvious. Ventilation is the low-hanging fruit of housing reform. All we need is to require effective mechanical systems that quietly bring in fresh air and automatically extract damp, stale air from every room to the outside. Ideally, these systems also recover heat so fresh air doesn’t mean cold air. The benefits are immediate: healthier families, healthier buildings, and lower long-term costs.
That’s why I believe the Code must change. All homes should include balanced ventilation systems. And ventilation systems should be tested at sign-off so we know they actually perform as designed. In addition, the code should require kitchen rangehoods and bathroom fans to be on automatic timers linked to either the light or a humidity sensor.
The key takeaway is obvious: good insulation and glazing will not perform as well if the air inside is damp and unhealthy. Ventilation is simple, proven, and affordable, and while most countries already require it in new homes, New Zealand is one of the few still relying on the outdated idea that people will “just open a window.” If we are serious about warm, dry, energy-efficient homes, making ventilation standard is the next sensible step.
