People living in New Zealand’s newer townhouses and apartments will likely have to wait until 2031 before the Building Code says anything about how hot their homes are allowed to get, after officials confirmed overheating rules will not be part of the next code review in 2028.
The Ministry of Business, Innovation and Employment told RNZ on 28 September that it was working on the problem but would consider it in the following review cycle rather than the one due in two years. The Building Code currently has no controls on overheating and sets no maximum indoor temperature for a home.
The delay has dismayed the groups that have spent the past few years pushing for change. “We’re really shocked to hear that we’re facing a significant delay in dealing with this,” Green Building Council chief executive Andrew Eagles told RNZ. “That’s hugely alarming when you talk to these families and they’re in sweltering conditions.”
Residents of the many townhouses and apartments built in recent years have repeatedly raised concerns about dangerous summer heat, which advocates put down to common design flaws such as large windows, small rooms, little ventilation and no eaves or external shading.
Auckland homeowner Jared Laidlaw described his family’s experience to RNZ. They moved into a two-storey townhouse at the end of 2021 and found almost immediately that the upper floor overheated. The house faces west, has a floor-to-ceiling window in the main bedroom and no eaves. “You just have five or six hours straight of sun smashing that side of the house,” he said.
Upstairs temperatures typically reached 35 degrees during the day and were still in the high 20s late in the evening, he said. The aluminium front door got so hot in the afternoon sun that it radiated heat back into the house. “You can’t touch the door – it burns your hand.”
When their sons were born, Laidlaw and his wife kept thermometers around the house to check the babies were safe. They tried ceiling fans and a portable air conditioner before paying $2500 for ducted air-conditioning. He and a neighbour also bought a roll of foil-covered bubble wrap online and fixed it inside the window frames with Velcro. “That has made the biggest difference, aside from the AC,” he said.
Eagles said that combination of features was typical of many new builds. “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.”
The Green Building Council and the Building Research Association of New Zealand, known as BRANZ, both support an interim fix. They want designers to run a home through overheating modelling software at the design stage and adjust the plans until it passes a maximum-temperature test. Eagles said the software was already used by hundreds of firms around the country, and that the fixes it prompted would often be cheap ones. “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 the problem would only get worse as average temperatures climbed, and that the rules could be brought in in stages rather than all at once. “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,” he said.
The ministry’s case for waiting is that overheating is more complicated than it looks. In a written response to RNZ, MBIE manager for building performance and engineering Dave Gittings said officials were working through how overheating requirements could fit into the Building Code. “We need to make sure any changes work together as a package and don’t create unintended consequences elsewhere in the building system,” he said. “That includes considering an approach where designers would need to demonstrate through modelling that their designs will not exceed a maximum indoor temperature.”
Gittings said heat build-up depended on a long list of linked factors, including sun, shading, the materials used, ventilation, airtightness and which way a building faces. Bringing in a modelling requirement would involve more than simply setting a temperature limit, he said. The industry would need enough people capable of doing the modelling, and council building consent officers would need clear guidance on what evidence to ask for and what to check. The ministry would provide informal guidance to designers and homeowners in the meantime.
The 2031 date follows from the way the code is now maintained. MBIE’s Building Code programme of work, last updated in February, says the code is reviewed every three years with the next update due in 2028. Under the heading of internal environment, the same page lists the development of a methodology for assessing overheating risk in buildings as one of the topics officials are working on. Missing the 2028 round pushes any binding rule to the review after that.
The timing matters because of what is being built in the meantime. Laidlaw told RNZ that 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.”
Eagles was blunter. “Perfect is the enemy of good,” he said. “We should just get the bloody hell on with it.”
The issue sits awkwardly alongside the progress New Zealand has made at the other end of the thermometer. A BRANZ study published in June found that homes are now much warmer in winter than they were two decades ago, with heat pumps now heating more than 60 percent of homes. Keeping homes cool in summer has had nothing like the same attention from regulators.
For households already living in a hot new build, the fixes fall on them. Eagles said his organisation was already hearing from people horrified at spending tens of thousands of dollars, with children sleeping in rooms that were far too hot.
With summer only a couple of months away, many families in new townhouses will be reaching for fans and foil again long before any rule change arrives.
Is your home too hot in summer, or have you found a fix that works? Tell us about it in the comments below.
This article was written by AI, briefed to report the facts, hopefully without some of the bias people bring to the job 🙂
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