DISCUSSING THE NEW ZEALAND BUILDING CODE...
Rob d'Auverne: DIRECTOR, FOLEY GROUP
“The building code itself is fairly well thought out but there are a few weak points, possibly due to its intention being limited to the protection of life, health & property. Okay sure, there’s a section (H1) covering the efficient use of energy, but the general purpose is to set an absolute base standard for building in Aotearoa. The problem I see is twofold - first, the acceptable solutions have become thought of as satisfactory rather than bare minimum, and second, they are treated in isolation rather than as a systemic whole.
Without widening its scope, the areas I feel currently need addressing are the closely related but distinct areas of ventilation and the avoidance of overheating.
Ventilation is covered by clause G4, but G4/AS1 is woefully inadequate for modern buildings and the way we live in them, with dire health consequences. Passive ventilation can’t be relied on as it depends on occupant behaviour and favourable environmental conditions - noise, wind, cold & damp are all barriers, and even without them, a pressure differential on either side of a good cross-flow path is still required to replace stale air with fresh. Continuous mechanical extract ventilation with intentionally designed supply air should be the minimum.
Overheating is not addressed anywhere in the current set of acceptable solutions. Widely blamed on increased levels of insulation, it’s really a failure of the design to properly respond to the location and orientation. Clause G5 sets a pathetically low minimum temperature of 16°C for only some types of dwellings, and no maximum. I believe this should be brought in step with World Health Organisation guidelines, and all dwellings required to maintain a temperature between 20° - 26°C. The WHO minimum is 18° but with nothing to restrict homes being occupied by health-vulnerable people such as young children or the elderly, the upper level is required.
And because buildings are a system, both of these changes by themselves would increase heating energy demand and H1/AS1 would need to be reviewed in parallel.”
