Coping with heatwaves through better design

This has been a particularly hot summer in Australia. This means that people turn to air conditioning to improve comfort and reduce heat-related stress. With the impact of changes in climate, the problem is going to get worse, not only in Australia but in many other regions of the globe. Lydia Hales writes in The Guardian about the need to focus on building design as we move towards a low-carbon society.

 

Hot apartments: ‘If we need air conditioning, we’ve designed it wrong’

It was one of the most extreme heatwaves in south-eastern Australian history. During late January and early February 2009, temperature records were toppled across Victoria, South Australia and Tasmania.

Then, on 7 February, 24 of Victoria’s 35 long-term stations recorded record high temperatures: Melbourne reached 46.4C while Hopetoun broke a state record with 48.8C.

These extreme temperatures were said to have caused an estimated 374 deaths in Victoria.

And it could happen again. Research from the University of Melbourne shows that many Melbourne apartments aren’t designed to withstand heatwave conditions and could become dangerously hot for residents.

As temperatures continue to soar each summer, the researchers are calling for an upgrade to the Australian building code to include measures of apartment overheating during design, and for retrofit improvements to vulnerable apartments – and to bring the guidelines in line with international practice in a warming climate.

Using data from the 2009 January-February heatwave, the researchers modelled the performance of six apartment designs typical to Melbourne. The apartments were run without artificial cooling, to see “what happens from a health and safety perspective if the air conditioner breaks or the grid power goes out”, according to the lead researcher, Chris Jensen.

All apartments failed the international “summer comfort” standards from the UK, France, Germany and the United States.

Housing comfort isn’t simply a matter of being a little hot and bothered: heat stress claims more Australian lives than all other natural hazards. But the building code of Australia contains no standards to guard against this. Standards now focus on reducing energy requirements for cooling rather than directly addressing measures of heat stress.

After the deaths of 14,800 people from heat stress in France in 2003, the French building code now requires that buildings can maintain a “comfortable” indoor temperature without the need for active cooling systems. It stipulates that room temperatures do not exceed 28C for more than 260 hours throughout a year.

Jensen says modelling the effects of retrofit strategies, such as changing thermal mass, insulation, light-coloured walls and natural ventilation, resulted in even the worst-performing apartment improving enough to meet two of the four international standards.

“There is one fairly glaringly obvious outcome: that proper use of natural ventilation by the occupants was reported both in the literature and in the study to be highly effective and very under-used,” he says.

Jensen says the study could be expanded to analyse apartments across the country, although other areas have different heatwave profiles. “The further north you are in Australia, the less temperature variation there is – further inland also has higher variations, so one would expect Mildura to be pretty severe (but there are basically no apartments).”

He says it would be worthwhile considering other states: “I would expect Perth, Adelaide and Melbourne to be the worst, possibly Canberra as well, but … it is subject to there being apartments, and a weather pattern with severe heatwaves.”

The research confirms the thinking behind measures taken by a growing number of progressive Australian architects. Maintaining a comfortable temperature without using air conditioning was a priority when designing the Brunswick apartment building the Commons for Jeremy McLeod, an architect and founding director of Breathe Architecture.

“It’s really important to have well-performing windows,” McLeod says. “We paid more for that and it helped us increase our star rating. It also helped our thermal modelling, which told us we could then take out the air conditioning.”

He says the key message from the study is that cooling strategies should be applied together, adding that thermal mass and natural ventilation have worked well at the Commons.

“We have incredibly stable temperatures through winter and summer and to be able to get through the [January 2014] heatwave with no air conditioning, I think was incredible.”

As a result, they’re putting more thermal mass into their new Nightingale housing model.

“Everyone has been naive, so people have been ignoring climate change – they thought they could deal with it with bigger and bigger air conditioners,” McLeod says. “Until what happened in South Australia last year, no one had pondered the possibility that our grid would fail, and of course you need to allow for that possibility.”

He’s investigating the idea of heat refuges in co-housing – for example, a basement communal room with a high-efficiency air conditioner that can run on solar in emergencies.

Andrew Maynard, co-director of Austin Maynard Architects, isn’t surprised by the results of the study. “We know the health risks from some of the studies coming out about suburban living, but then to see that these things just turn into ovens and cook people, that’s alarming,” he says. The recommendations are encouraging, he adds. “There’s a way out.”

Maynard says the liveability of apartments in Australia suffers because they’re seen as commodities rather than homes.

“We need to remember that what’s legislated will be the norm. Why would they put expensive external shading on a western facade when they can just throw in a cheap air conditioner? We absolutely need to legislate this stuff because it’s the only reason developers would do any of it.”

He says their designs consider building orientation, maximise passive sunlight in winter and minimise it during summer, and optimise through-breezes. They know that if they need to introduce air conditioning “we’ve somehow designed it wrong”.

Another priority is helping residents understand how to passively manage the buildings’ temperature themselves. This understanding is important when people are looking at apartments, to drive demand for sustainable design, Maynard says.

Dimitri Kapetas, a co-director and designer at Fremantle-based architecture group EHDO, says their projects draw inspiration from designs in similar climates. An example is the Persian wind-catcher, which can be combined with an underground canal, using air pressure differences to draw air down over the water and reduce the temperature.

“You can almost get it down to iced temperatures; I’ve been to a couple in North India and it was freezing down there on a 40C day,” Kapetas says.

Diluted versions of these ideas can easily be applied to new buildings, he says.

“If you put a water source and/or vegetation in front of a large opening in a building on the south-western side – where the cool breeze comes from in Fremantle – and a small, high opening at the other end of the house, the breeze drops around 1-2C,” Kapetas says.

For Western Australia’s first Nightingale project, they plan to make the warmer winds from the north-east travel over water and vegetation to cool before they hit the building.

The design will also involve a six- to seven-metre-wide “green street” that channels wind through deciduous trees, with little wind-catchers to funnel the air into the apartments on either side. All apartments will have two north-to-south windows.

“I don’t want to be preachy,” says Kapetas, “but those [suggestions in the report] are things that should almost just be standard design … there are really simple things that can be done for not much more cost.”

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