It’s time to heatproof our cities

Eureka Street
Eureka Street

A FEW WEEKS AGO, as a cool change swept away Melbourne’s mid-January heatwave, my partner and I went for a walk around our block. The air temperature had plummeted about ten degrees in 30 minutes, but as we passed a new two-storey home with no surrounding vegetation and a mound of gravel for a front lawn, I felt a surge of residual warmth. The house’s dark-grey exterior seemed to shimmer with stored-up heat.

Hurrying on, I wondered how this house — and so many others like it — would cope with future heatwaves.

Climate change has loaded the dice towards hotter days and more frequent heat spells. Australia’s average temperature has increased 0.9 degrees since 1910, while the number of record hot days has doubled since 1960. ‘Although Australia has always had heatwaves, hot days and bushfires, climate change has increased the risk of more intense heatwaves and extreme hot days, as well as exacerbated bushfire conditions,’ explained the Climate Commission’s 2013 report ‘Off the Charts: Extreme Australian summer heat’.

Heatwaves don’t create the same dramatic news footage as bushfires, floods and cyclones, but they kill more people. From 1844 to 2010, heatwaves were responsible for at least 5332 deaths in Australia, and since 1900 they’ve killed more Australians than all other natural hazards combined. The January 2009 heatwave in Victoria, when Melbourne sweltered through three consecutive days of temperatures above 43 degrees, resulted in 374 deaths. In comparison, the Black Saturday fires took 173 lives.

While peak temperatures fell short of the 2009 heatwave, the severely hot weather across south-eastern Australia from 13 to 18 January this year lasted longer in many places. Adelaide had a record five consecutive days of 42 degrees and above, and Canberra had a record four consecutive days of 39 degrees. Sydney was spared the worst of the heatwave this time around, but last January the city registered its hottest day on record.

Meanwhile, Victoria had a record-breaking average maximum temperature of more than 41 degrees across four successive days, resulting in 139 ‘excess’ deaths in the period up to 23 January.

The elderly are more vulnerable to extreme heat, and Australia’s ageing population means we can expect the death toll to rise in the future. But the biggest impact will come from climate change. A November 2011 report from PricewaterhouseCoopers modelled the effect of future heatwaves on Melbourne and found that, by 2050, climate change could multiply annual average heat-related deaths by five. Melbourne isn’t alone — the ‘State of Australian Cities 2013’ report predicted heat-related deaths to increase dramatically in Perth and Brisbane.

Unfortunately, the majority of Australian homes are reported to be 20 or more years old, and they don’t cope well in long periods of very hot weather. A CSIRO analysis published in 2013 by the National Climate Change Adaptation Research Facility modelled the performance of 10 typical housing types during the January 2009 Melbourne heatwave and found that a safe temperature threshold was breached in every single house type, although insulation did significantly reduce the duration of the risk.

If you lived in a ‘worst case’ house — with poor orientation, a dark roof and no insulation — you’d probably be better off outdoors.

Newer houses generally have improved insulation, but a 2008 study found the energy-efficiency of residential buildings has been ‘outpaced by the rate of increase in average floor area’. Despite having higher energy ratings, our big new homes require more energy to heat and cool overall.

Not surprisingly, more Australians now own air conditioners and evaporative coolers — up from 59 per cent in 2005 to 73 per cent in 2011. This has advantages, as the quick relief of artificial cooling can save lives during a severe heatwave.

But while offering a short-term solution for individuals, air conditioners increase the long-term vulnerability of society. Firstly, their use ramps up peak energy demand, leading to power outages and ‘load shedding’ to make up for the shortfall in electricity. When electricity consumption topped 10,000 megawatts in Victoria on 15 January this year, tens of thousands of people were left without power.

Secondly, increased peak demand requires additional infrastructure, which jacks up electricity prices for everyone, but is particularly devastating for the poor elderly who are most vulnerable to heatwaves. Older Australians on pensions might be reluctant to turn on their air conditioners — or even their fans — due to prohibitively high bills.

What’s more, thermal infrared maps of Adelaide, Melbourne, Sydney and Brisbane show concentrations of low-income households in hotter areas of the city with little vegetation. The people who can least afford the cost of summer air conditioning live in locations where it’s most needed.

Several proposals have been put forward to address these issues. New ‘smart’ air conditioners are fitted with devices to allow power companies to switch off the electricity-hungry compressors for short periods during peak loads, potentially reducing power outages. The Australian Medical Association has previously called for government to subsidise the cost of air conditioners for the elderly.

But even with these changes, relying on air conditioning is a risky strategy. As an energy-intensive technology, air conditioning increases carbon emissions that contribute to climate change, fuelling hotter and more frequent heatwaves. The real solutions lie in strategies that keep us cool without simultaneously heating the planet.

The National Climate Change Adaptation Research Facility has put together a framework that recommends a more holistic approach to the spectre of future heatwaves, including retrofitting roofs with reflective surfaces and ceiling insulation. Air conditioners are still part of the solution, but should be regulated to reduce peak demand. Houses could be fitted with a ‘cool retreat’ in one room, reducing the need to chill the entire interior.

Other reports have recommended more vegetation around the city and a shift from private cooling to collective cooling by establishing public spaces where all citizens can access cool air for free.

Heatwaves are only going to get worse, and air conditioning isn’t the godsend it seems. We need to start retrofitting our cities, suburbs and homes to withstand the sweltering summers to come. Any new houses that perform poorly in the heat — like the one I saw on my walk around the block — are going to be a tremendous burden on the next generation.

First published in Eureka Street.