Ministry delays rules on too-hot homes

By Kate Newton of RNZ

Advocates for people living in overheating new builds are dismayed that officials will not consider comprehensive changes to fix the issue until 2031.

Residents of the glut of townhouses and apartments built in the last few years have repeatedly raised concerns about dangerous heat in their homes during summer, because of common design flaws.

The Building Research Association and Green Building Council are among organisations advocating for changes to the Building Code, which currently does not include any controls on overheating or maximum internal temperatures.

However, Ministry for Business, Innovation and Employment officials have confirmed the issue would not be part of a regular code review in 2028, and instead would be considered during the subsequent review in 2031.

“We’re really shocked to hear that we’re facing a significant delay in dealing with this,” Green Building Council chief executive Andrew Eagles said.

“That’s hugely alarming when you talk to these families and they’re in sweltering conditions.”

Jared Laidlaw and his family moved into their two-storey Auckland townhouse at the end of 2021 and discovered almost immediately that the upstairs overheated.

The house was west-facing, with a floor-to-ceiling window in the master bedroom, minimal ventilation, no eaves and no external window shading.

“You just have five or six hours straight of sun smashing that side of the house,” he said.

Temperatures upstairs typically got to 35C during the day and were still in the high 20s late in the evening, he said.

Some parts of the house were not just uncomfortable but dangerous – like the aluminium front door, which reached 60 or 70 degrees on a summer day and radiated heat back into the house.

“You can’t touch the door – it burns your hand.”

When his young sons were born, he and his wife were hyper-vigilant about monitoring the temperature.

“We used to have thermometers and stuff because ... it’s not safe for babies.”

In the time they had lived in the house, they had tried ceiling fans and a noisy portable air-conditioning unit, and finally paid $2500 for ducted air-conditioning.

He and his next-door neighbour ordered a roll of foil-covered bubble wrap from Temu, which they used to make huge shades that could be attached by Velcro to the internal window frames.

“That has made the biggest difference, aside from the AC,” he said.

“This will stay up weeks or months at a time ... We can’t enjoy the view because it’s 35C in here during the day.”

The features that contributed to overheating at Laidlaw’s house were typical of many new-build townhouses and apartments, Andrew Eagles said.

“You’ve often got windows going floor to ceiling ... you’ve got no eaves and no shading allowance,” he said.

“You’re then getting the full effect of the sun during the day and smaller rooms, so the combination of all of that is you just get this massive heat build-up.”

His organisation and the Building Research Association both supported an interim fix to a schedule in the Building Code that would require modelling at the design stage to check if a dwelling would overheat.

The software capable of doing that modelling was already used by hundreds of firms around the country, he said.

“I [would] need to put into a calculator the size of the home, the orientation, the size of the windows, and then it comes back and says, oh look – you are going to overheat this proportion of that time.”

The design would then have to be tweaked until it was under the modelling limits, Eagles said.

“The steps people are likely going to take is reduce the amount of glazing – that will save them money – or put some shading on or put some eaves on or slightly change the orientation, those sorts of things.”

Branz senior building physicist Stephen McNeil said without regulation, people in Laidlaw’s predicament would suffer even more as average temperatures increased.

“It’s also those extremes ... and we have other concerns with the increasing humidity in the air as well.”

In a written response, MBIE manager for building performance and engineering Dave Gittings said overheating was a complex issue without a single fix.

“We need to make sure any changes work together as a package and don’t create unintended consequences elsewhere in the building system. That includes considering an approach where designers would need to demonstrate through modelling that their designs will not exceed a maximum indoor temperature.”

The 2031 review was appropriate timing because of the considerable technical and policy work involved, he said.

“Overheating is influenced by a broad range of interconnected factors, including solar gain, shading, the heat absorption of building materials, ventilation, airtightness and building orientation. It takes time to consider any consequences, develop options for change and thoroughly consult on any changes to ensure we’ve considered every angle before implementing them.”

The ministry would provide informal guidance to designers and home owners in the meantime.

Introducing a requirement such as the one proposed by the Green Building Council would involve “more than simply setting a temperature limit”, Gittings said.

There would also need to be appropriate capability among those doing the modelling, which would require industry acceptance with any changes, with clear expectations for building consent authorities about the evidence they should receive, what they needed to check and when specialist review may be required.

But Stephen McNeil said changes could be staged.

“Rather than one big hit where you deliver this perfect regulatory thing that solves every problem, you’ve got to take the industry on a journey and give them time to build into it,” he said.

“Simple measures now will save us a lot of pain down the track because we could capture the riskiest buildings quite early in the piece.”

Andrew Eagles said in this case, “perfect is the enemy of good”.

“We should just get the bloody hell on with it.

“We’ve already got people writing to us horrified that they’re spending tens of thousands of dollars and that their kids are in rooms that are far, far too hot.”

Jared Laidlaw agreed five years was too long to wait.

“I’d anticipate a lot of houses in between now and then are going to be townhouses, so you’re going to only exacerbate the situation,” he said.

“It’d be a great time to be an HVAC business.”

 This story was first published on rnz.co.nz