Melbourne apartments are not built to cope with heatwaves, new research from the University of Melbourne has found, putting at risk the health of occupants.
The findings from the THRIVE Research Hub come as governments consider taking changes to residential performance standards off the table until 2022.
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The research modelled six apartment designs typical to Melbourne (including low and high-rise, old and new, and minimum standards and best practice) and tested them against four international standards that “represent best practice in protecting the health of apartment residents in heatwave conditions”, mostly by limiting the amount of time an apartment interior can be above a certain temperature.
These standards included Germany’s Passivhaus, France’s Norme Française Haute Qualité Environmentale, the UK’s Chartered Institution of Building Services Engineers guide, and the US’s American Society of Heating, Refrigerating and Air-conditioning Engineers standard.
Lead researcher Chris Jensen said the research was motivated by severe recent Australian heatwaves, and data from the deadly 2003 heatwave in France.
“[France’s] deadly heatwave claimed over 14,000 lives,” Mr Jensen said. “This led to French authorities legislating for all homes to be comfortable during five consecutive hot days in ‘free running mode’ – without heating or cooling.”
Performance was modelled on how apartments would cope in “free running mode” under the conditions of the 2009 Melbourne heatwave, where daytime temperatures exceeded 43°C for three days and nighttime temperatures were above 25°C.
“Heatwaves of this extreme and duration are predicted to occur more frequently and many apartment occupants are likely to suffer regardless of their age,” Mr Jensen said.
The results found that no apartment complied with any of the international standards.
Construction standards questioned
“The fact that all the Melbourne apartment types that have been modelled cannot maintain safe internal environmental conditions raises concerns about the standard of construction in Melbourne,” the research report said.
The researchers then sought to model how retrofitting the apartments would affect the results.
Standard retrofit strategies – such as increased insulation, thermal mass, light-coloured walls, natural ventilation and window shading – were employed, and caused up to an 85 per cent reduction of hours inside the heat stress zone. The strategy with the most impact was natural ventilation, with a reduction of up to 71 per cent in the number hours above the maximum temperature threshold. The researchers said this was “easily retrofitted to most apartments”.
The worst-performing apartment was able to meet two of the four international standards through standard retrofit technologies.
“Thermal mass, the capacity of building materials to absorb and store heat, shading and glazing orientation, overwhelmingly determine indoor temperature during heatwaves,” Mr Jensen said.
Building regulation change needed
The researchers said building regulations should be changed to consider thermal comfort and overheating in light of the growing frequency and intensity of heatwaves.
“Any new regulation would require additional thermal modelling that is not currently allowed for under the traditional Building and Construction Authority compliance methodologies,” Mr Jensen said.
“Our recommendation is that the Australian Building Codes Board (ABCB) who administer the [Building Code of Australia] should review opportunities to design to reduce overheating as a standard requirement, specifically for apartments,” the research report said. “This might include a requirement to assess the design in free-running mode to determine comfort levels across a period of time.”
The report also said existing buildings should seek review of strategies to pursue building thermal performance and mechanical cooling to protect occupants “as a priority”.
“This may include façade retrofit or building services upgrades.”
- Read the full report.