Dark roofs, masonry, lack of shading elements, reliance on artificial cooling, and insufficient greenbelts are some of the urban design mistakes responsible for the urban heat island effect in cities, says Professor Chris Knapp, chair of architecture at Western Sydney University.
Rapid urban development, increasing city populations and rising summer temperatures are drawing focus to the issue of urban heat islands, which cause grey infrastructure such as roads, carparks, footpaths, roofs and buildings to continue to radiate heat long after sunset, causing discomfort to communities.
Calling for new constructions in Western Sydney to take heed, Knapp says local councils must be proactive in supporting and developing sustainable design.
“If not for buildings and infrastructure, we would not have an urban heat island effect, but it is a consequence of how our societies are formed today,” he says.
Pointing out how popular design trends are the very cause of urban heat increases, Knapp explains that dark roofs and unshaded heavyweight materials such as brick and concrete blocks absorb more heat than light coloured surfaces. Additionally, high-density materials such as masonry retain heat very well, and expel and re-radiate heat long after the sun goes down, while homes that don’t feature shading devices or screens fail to protect inhabitants from the sun.
Relying on air-conditioning for cooling instead of effective insulation and ventilation in the building design as well as insufficient greenbelts and parks between property developments causing slow dissipation of heat are the other reasons listed out by Knapp for the rising urban heat island effect.
Smarter buildings and public spaces need to be designed to mitigate this issue, says Knapp, adding that extreme urban heat has significant impact on public health, energy consumption, animal behaviour and global warming.
Dr Sebastian Pfautsch, senior researcher in Urban Ecosystem Science, works with local governments in western Sydney to document baseline conditions of urban heat and develop strategies to mitigate its impact.
“Although today even pre-school kids learn about sustainability, the new suburbs built across western Sydney are far removed from this concept. No outdoor shade, no cool-roof or cool-street technology, no smart stormwater management, long commutes to work, high degrees of isolation,” says Pfautsch.
He calls on councils, developers and researchers to join forces and develop demonstration sites “where the public can experience firsthand what sustainable urban design looks and feels like. We must start collecting the evidence that is necessary to drive change in standards, codes – and importantly public perception and demand.”
Dr Abby Mellick Lopes, Senior Lecturer in Design and lead of the Institute for Culture and Society’s Cooling the Commons project, says building and public space design is a crucial element in preparing cities for extreme heat events.
Infrastructures such as shaded outdoor seating and drinking fountains that made public spaces more liveable in the past have declined, with many western Sydney residents now having little access to shade, outdoor shelter or public drinking water.
Lopes recommends involving people in the design of the material and social environments in which they live.
“Cheap construction that relies on air-conditioning to the detriment of quality public space is untenable. Cooling is also a community issue,” she says. “We need social strategies for living well in a climate-changed future, such as promoting greater use of riverside parks and public spaces in the evening, as practiced in other hot environments in Asia and the Middle East.”