‘It reached 38 degrees’: rental properties across Australia routinely exceeding safe temperatures, study reveals

Karen Thorne's rental home heats up as soon as the morning sun hits her east-facing bedroom in the Sydney suburb of Rosemeadow.

"I could wake up at 8am to 28-degree heat in there," Thorne said. "The heat is what actually wakes me up."

Thorne's bedroom is at the front of the home, but it's the back bedrooms, which receive the full glare of the afternoon sun, that get the hottest. Thorne's 19-year-old son took to sleeping on the kitchen tiles over summer because the heat in his room was unbearable.

"I've recorded on my own thermometer before - it actually reached up to 38 degrees in there one day, and it didn't cool down until 2am in the morning. That's why [son] Connor likes to perch on the floor in the lounge room, or in the kitchen. I am just grateful I have an en suite so I don't trip over him in the night," Thorne said.

Thorne's story is one of 49 captured in Hot Homes, a new report by tenants advocacy organisation Better Renting, illustrating renters' experiences of heat and heat management in their homes over the past summer.

The organisation recruited 49 renters around Australia to install temperature monitors in their houses from 1 December to 22 February, which measured minute-by-minute changes.

Even in this relatively mild summer characterised by La Nina conditions, including increased rainfall and cooler daytime temperatures, the researchers found causes for concern.

Homes were routinely exceeding the recommended safe maximum temperature of 25C, with household temperatures across the country between 25C and 30C for 38% of the time. Temperatures above 30C were recorded 4% of the time on average.

The houses also retained heat for a long time overnight, with temperatures hot enough to impair sleep 45% of the time.

In the Northern Territory, Western Australia and Queensland, the temperature inside the renters' homes was between 25C and 30C more than 50% of the time. In the Northern Territory, the tracked homes only dipped below 25C for 4% of the time.

The report follows calls in February for mandatory minimum building and rental standards that allow tenants to keep their homes sufficiently cool.

No jurisdictions in Australia have explicit requirements for cooling devices in rental properties. Recent changes to rental laws in Victoria, for example, include a requirement for landlords to provide a fixed heater in "good working order". But there is no comparable requirement for cooling.

Extreme heat is the leading cause of natural hazard fatalities in Australia, killing more people than all other natural disasters put together. According the Australian Bureau of Meteorology, the number of days of extreme heat has increased five-fold in the past 30 years.

Some of the renters who monitored their household temperatures for Hot Homes reported experiencing extreme heat indoors, even when the outdoor temperatures were relatively mild.

Kate Fox, who rents with and cares for her elderly parents in an apartment in Chermside, Brisbane, recorded a maximum indoor temperature of 37.5C over the summer, despite the apartment having only been built in 2017, having an air conditioner installed, and fans placed throughout.

Fox said the cooling mechanisms were offset by the box-like balconies that trapped sun glare, and open windows being in close proximity to other apartments' air conditioners expelling hot air.

"After it gets to a certain heat, up to about 28 degrees, you actually can't cool it down. There's no air flow through the windows. We had two fans in every room and it just wasn't enough. We'd have cold showers. We couldn't eat. We were just in this bubble of hot air," Fox said.

She was concerned about the effect the relentless heat was having on her elderly parents.

"It's hot like this for months at a time which, when people are very old and disabled, is very concerning," she said. "Particularly for my father, he'll spend weeks at a time just in a daze."

The Hot Homes report found this was a common problem among those who lived in new dwellings, leading researchers to suggest the standards set by the National Construction Code - which is currently under review - were inadequate, made assumptions about resident behaviour that did not bear out in practice, and didn't adequately take into account the changing climate.

Thorne's house also has an air conditioner installed, but it has required repair since 2020 - work which has not been completed. Thorne said she has not been allowed to install her own blinds or shutters, and there are no trees on the property that shade the house.

"I'm pretty disgusted in the way things are as far as renters are concerned. If you're paying money to live in a property with features that were advertised in the lease notice, you should be able to use those features," Thorne says.

Better Renting's Joel Dignam said trying to manage constantly stifling temperatures had knock-on effects in other areas of renters' lives, including their mental health and their performance at work.

"These effects come from a sense of powerlessness. People talking as if their home is their enemy and they have a need to escape from it. That's cumulative stress," Dignam said.

Renters also reported they felt powerless to speak up about the heat in their homes - even to request reasonable repairs, let alone alterations or new features be added to a property - for fear of eviction or retaliatory action such as rent increases.

Dignam said there was scope to make minimum rental standards more explicit, which may help tenants in seeking modifications to the property.

"Landlords have an existing obligation to keep their property 'habitable'" he said. "But if we can make it more concrete - there's got to be bathroom ventilation, fly screens on windows, ceiling insulation, etc. - that makes it easier for tenants to know where they stand."

The report could be seen as a warning, Dignam said.

"The summers we've experienced already demonstrate the impact of climate change, but this was a mild one. We are really concerned about what this means for future summers, which we know will be longer and hotter. We've got time to realise this is a problem and do something about it, but it's really something we need to get on to now."