In the European heat wave of 2003, 14,802 excess fatalities were recorded in France alone as temperatures rose above 37 degrees Celsius for seven consecutive days.
Fatalities occurred disproportionately amongst the elderly or chronically ill.
Whilst tragic, such events highlight the dangers associated with extreme temperatures, especially among the frail and elderly. They also highlight concerns associated with the growing number of elderly and/or vulnerable people who live in multi-storey apartments from which they may not be able to use the stairs to escape the building if and when extreme heat overwhelms the power grid and lifts and air-conditioners do not operate.
These dangers are increasing because of three factors.
First, the number of days where extreme temperatures will be recorded will increase as global temperatures rise.
Second, the number of people at risk is growing. In 2012, ABS data indicates that Australia had 3.2 million people who were aged 65 years or older. According to the agency’s projections, these numbers will rise to between 5.7 million and 5.8 million by 2031 and to between 9 million and 11.1 million by 2061.
Finally, the number of people living in multi-storey dwellings is rising. In calendar 1997, around 2.3 detached houses were approved for construction for every multi-unit dwelling. By 2017 – admittedly an abnormal year – there were nearly as many non-detached (mostly multi-storey) dwellings approved as there were detached houses given the go-ahead. Much of the often vulnerable social housing population is catered for in multi-storey units. As land costs rise, aged care residents may increasingly be housed be in multi-storey dwellings.
This underscores the need for apartment design strategies which minimise overheating risk. It also highlights the need for measures such as back up power generation and contingency plans for heatwaves and other extreme weather events.
Sadly, evidence suggests that efforts thus far are lacking.
In aged care facilities, research conducted by University of Sydney health science researcher and senior lecturer Dr Leigh Wilson found that only five per cent had back-up generation. Many residents of multi-storey apartments, meanwhile, are unaware as to whether or not their building has back-up power to maintain cooling and lift access during blackouts, Leigh says.
These problems are exacerbated by inherent challenges which make high-rise apartments reliant upon mechanical air-conditioning and thus susceptible to overheating if the electricity fails.
In a Melbourne-based study released last year, University of Melbourne lecturer and architectural science researcher (sustainable design) Chris Jensen modelled six common apartment designs and how these could cope with extreme temperatures such as those experienced in January and February of 2009. All six designs failed to keep internal temperatures below limits set in France, the United Kingdom, Germany and the US (currently, there are no standards to protect against heat stress in the National Construction Code in Australia, though there is a Proposal for change to incorporate separate heating and cooling loads into NCC 2019).
According to Wilson, multi-storey apartments are challenging for elderly residents.
“If you’ve got an older person in a high-rise apartment, many are not able to use the stairs in an extremely hot day,” she said.
“If the power grid overloads and they are relying on electricity to run the lift or put the air-conditioning on, we set up a situation where people are virtually isolated within their own home (and are unable to escape the heat inside the apartment).”
Furthermore, Jensen says several factors mean apartments are dependent upon mechanical air-conditioning.
First, there is orientation. Unlike many single-storey houses, apartments typically have a fixed orientation which cannot be altered to reduce extreme heat. This is problematic for apartments facing west. It is also troublesome in the case of smaller apartments or studio apartments where residents are afforded little in the way of opportunity to seek refuge in cooler rooms facing south or east.
Next, with ceilings and walls being shared with adjoining dwellings, apartments often provide few opportunities for cross ventilation.
Combine this with facades that are heavily glazed and the growing popularity of curtain wall systems (often chosen for reasons such as wind pressure) which do not have openable windows, and many modern apartments deliver little opportunity for heat loss.
On that note, Jensen says a number of tall buildings have similar facades on each side. This becomes problematic as a heavily glazed façades may exacerbate overheating west facing units notwithstanding their ability to deliver attractive views and adequate heating performance on the cooler south side.
Finally, use of external shading to block heat from hitting windows is difficult with apartments.
Jensen commends the building sector for improving the overall energy efficiency of new residential dwellings. But he says good energy performance overall does not necessarily translate into comfortable buildings in heatwaves. Indeed, his research uncovered overheating challenges not just in old buildings but also in newer buildings and dwellings whose overall energy consumption was low.
He says Australia needs to follow international examples and adopt a comfort standard. In the United Kingdom and France, for example, buildings are required to be assessed as not being expected to heat up to above 28 degrees for a certain number of hours per year. One Proposal for Change in NCC 2019 would see separate load limits for cooling as well as heating.
Whilst he acknowledges challenges and the need to balance heat-resistance with other design related considerations (openable windows create wind load and child safety considerations, for example), Jensen says anything which can be done in shading and ventilation will help.
He rejects suggestions that ventilation will not be effective because people will not open their windows when the air outside is extremely hot. Ventilation, he says, enables heat to escape once the temperature outside cools. This reduces the amount of time during which rooms stay hot.
Wilson hopes her research will promote discussion about how elderly and vulnerable residents can be catered for in a heatwave. She says this involves looking any strategies which enable people to access airflow, building access measures which can assist vulnerable residents to exit the building and consideration of backup power or other measures.
She adds that growing use of vegetation on multi-storey buildings is a positive step. So too is increased use of courtyards and social meeting spaces which help to foster social interaction and reduce the likelihood of people being alone in an emergency.
She says Australia must act now.
“We know that each year is getting hotter and hotter and that periods of heat are lasting longer,” Wilson said. “We really need to do something now rather than have a situation like France and say, ‘we should have done something differently.’
“If you think about the way buildings were built 100 years ago, they were built for the climates with louvres and breezeways through the house. Now, we are changing our buildings and our climate is getting worse.
“We do need to think about it.”