Stephen McNeil: Building Research Association Senior Building Physicist on the overheating problem in new-builds, review pushed back to 2031
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Why are overheating fixes for New Zealand homes delayed until 2031?
Hard to believe in twenty twenty six we're still dealing with chonky building issues, but the latest one is not only a problem, its so called solution has been delayed. So MB is working on the overheating issues, right? But any changes are not going to be part of the twenty eight building code review. In fact, overheating won't be dealt with until twenty thirty one. Uh Stephen McNeil is a senior building physicist at the Building Research Association and is with us. Stephen, morning to you. Good morning, Mike. How's it going? I'm very well indeed. Do excuse my ignorance. I just find it hard to believe we're building these sort of buildings and yeah, forget the rules. Why are we building houses that overheat in twenty twenty six?
Why do building standards focus on keeping homes warm instead of preventing summer overheating?
Well, fundamentally we don't actually look for overheating risk um during a building code uh s sort sort of during building compliance or any s building code assessments. So it's it's really that we've been focused so much on Trying to keep heat in for for winter obviously. Um and then trying to build more dense. That that's one of the big things we're doing. But what do you
counterfactual to that if you're a designer, an architect or a builder go, if we seal a house really nice and tight so we keep the heat in, someone's gonna go, But yeah, what about in summer? It might get a bit warm?
Yeah, and and the main thing there is you actually have to treat a building as a as a whole system and I think that's that's where things have have slipped up. Yeah. So we're we're treating it and and treating it.
Because it just strikes me as idiocy.
Well, I think it comes down to to training of the industry in general.
How do building industry training and construction pressures contribute to overheating?
Um it's there there's a there's a really fast moving um branch of science in this area and and a whole pile of different areas that that that they have to try and keep up with. But from the rules and planning perspective, Yeah, it sounds like a really simple thing, but when when time is money and they're trying to get houses cranked out quickly, yeah. They're just following the rules and just doing what they can to to make a living.
And when you say cranked out quickly, are we we stuck here mainly on town houses or can it happen to anything?
It can happen anything. So like our heat two data from where we've done a a big survey of homes around New Zealand, um, we found about seventy percent of people complained that their houses were too hot than than what they would like in summer. Um for some of the time. Twenty percent of them were saying that for all of the time. So it's uh that's That's pretty bad, but it's really the the dense typology.
Why are townhouses and multi-unit homes especially prone to overheating?
So like your your townhouses, your multi units that have lots of floor to ceiling glass, maybe only one side of the building. opens up so you can't actually cross ventilate properly. And the the big problem is once once the sun hits the glass it's all over. If if you're not actually shading that glass or putting some some solar treatments on that glass. And you're basically treating that that house like a greenhouse.
Okay. So d do we need MB to do something with the rules that will solve the problem, or can we solve the problem ourselves with some common sense and some brain power?
I think I think the it's a combination of the two. So I think early on we can like right now we can tell people, Hey, you should start be using
How can building modelling identify overheating risks before construction?
you know, modelling to to understand how a house is going to perform before or after any kind of changes. And it's cheap to do when it's at the design stage. Yeah. If you do it once it's already built, that's that's not that's not really affordable. But at the design stage You can you can use them online. In saying that, modelling isn't doesn't have a huge uptake. Um, so we do need some simple rules that we can put in for everyone else. So you're disappointed in not doing it to
twenty thirty one?
Yeah, yeah.
What simple building code rules and shading measures can reduce overheating?
So the the simple rules thing we we could do something now. And there are bits, say, in the commercial part of the H one um part of the building code. where there's a thing called a solar aperture, where you basically have a simple calculation
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Chapters
6 chapters
1
Why are overheating fixes for New Zealand homes delayed until 2031?
0:00–0:33
2
Why do building standards focus on keeping homes warm instead of preventing summer overheating?
0:33–1:24
3
How do building industry training and construction pressures contribute to overheating?
1:24–2:11
4
Why are townhouses and multi-unit homes especially prone to overheating?
2:11–2:53
5
How can building modelling identify overheating risks before construction?
2:53–3:19
6
What simple building code rules and shading measures can reduce overheating?
3:19–4:09
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