Around 70% of New Zealanders find their homes too hot at least some of the time in summer. Those in townhouses are suffering much more than most, writes Catherine McGregor in today’s extract from The Bulletin.

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A summer of broiling indoor temperatures

As temperatures begin to feel more autumnal over the next few weeks, the sweaty, sleepless nights of summer will fade into memory – for a while at least. Before we know it, the summer temperatures will be back, and so will the complaints about uncomfortably hot homes. New research from the Building Research Association of New Zealand (Branz), based on a survey of New Zealanders in summer 2023/24, finds that 70% of people experience indoor temperatures warmer than desired for at least some time during the summer. Interestingly, more Wellingtonians than Aucklanders say their homes are too hot always or often (29% vs 24%), despite lower temperatures recorded in capital city homes, reports BusinessDesk’s Greg Hurrell (paywalled).

Townhouses a key culprit

Only 14% of Cantabrians report being too hot at home always or often, a perhaps surprising result given the type of housing that is most associated with Christchurch. The garden city is now the townhouse capital of New Zealand, reports Stuff’s Brianna McIlraith, with townhouses making up 24% of its housing market, the highest proportion in the country. Townhouses are hot property in more ways than one. In December, as the summer heat began to take hold, a Christchurch townhouse resident told 1News that temperatures in his bedroom sometimes exceeded an inhumane 50C. In Auckland, a heat pump installer said his company had changed from a “winter heating business to a summer cooling business”, with up to a half of summer installations going into high density housing.

Insulation not the issue

The high summer temperatures inside many NZ homes were among the issues under discussion in the recent consultation on reverting new-build insulation rules back to their less strict, pre-2021 settings. While building and construction minister Chris Penk says he’s focused on lowering build costs, he also cited concerns that the stricter insulation requirements were contributing to overheating and dampness risks in new housing. That’s a myth, say industry experts. “Large windows, a lack of eaves or other shade, no consideration of a property’s direction towards the sun, and poor ventilation” are the real culprits, the Green Building Council’s Matthew Cutler-Welsh tells Raphael Franks of the NZ Herald. The Branz survey found “no significant correlation between the householder reporting their home warmer than they would like in summer and the level of roof space insulation”.

Stricter rules on townhouse design needed, says industry

As the government mulls lowering insulation standards – to the dismay of many in the industry – experts are calling for tighter rules on high density design to be added to the Building Code. Writing in The Spinoff, Kasey McDonnell says the solutions are relatively simple. “It’s stuff like adding overhangs above windows to shade them, or not pointing giant windows north, or improving ventilation.” McDonnell, who lives in a north-facing Wellington apartment that gets “really hot” in summer, says high density homes are a key weapon in the fight against the climate crisis – so it’s vital we get their design right. “Apartments aren’t inherently unliveable in a warmer world,” he writes. “Badly designed housing is the problem.”