Do dark roofs heat up the hood?
A self-confessed "angry grandma" is fighting to cool down Perth's hottest suburbs
PT0M45S 620 349A self-confessed "angry grandma" is fighting to cool down Perth's hottest suburbs, urging the state government to outlaw black roofs when it finalises a planning policy review.
The kinds of suburbs a recent study measured as Perth's hottest were same ones featuring new developments with seas of black roofs, Hocking resident Joan Day said.
New homes in Perth suburbs are being built with black, heat-absorbing roofs and have no shade around them to compensate. Photo: Emma Young
Mrs Day is now campaigning to have light-coloured roofs mandated and is outlining her research in a submission to the state government's Liveable Neighbourhoods planning policy review, now open for public comment.
"Look at Banksia Grove, Hocking, Tapping, Annie's Landing and Landsdale on Google Earth to see all the black roofs," she said.
"Right now to my utter disgust, hundreds of new houses are being built in Annie's Landing with dark roofs and the primary school also has a dark roof – there are acres of black roofs.
Another example of a new home in Perth with a black roof and little shade. Photo: Emma Young
"Dark roof spaces reach 80 degrees on 40-degree days. Houses can be 10-20 degrees hotter even with insulation," she said.
"The school opens next year and my grandson will attend.
"I am one angry grandma."
The science on the "urban heat island effect" - a phenomenon in which air temperatures are higher in urban areas – back her claims.
The author of 'Perth's hottest suburbs' study, environmental consultant Paul Barber, has pointed to dark roofing on developments as a major culprit in the urban heat island effect, as has Curtin University School of Public Health director Helen Brown, who runs workshops.
The state government's Environmental Protection Authority recently predicted heat-wave related deaths in Perth would more than double by 2050.
Ms Day pointed out that houses in many of these developments were almost fence-to-fence and in many cases had no easements, small or nonexistent eaves, poor orientation and inadequate insulation.
They were also in areas with hot winds in summer and poor sea breeze penetration.
She said a public education program regarding black roofing was required.
"It is a basic human right to have a shelter which protects us from the elements: rain, hail, storm, heat and cold," she said.
"In this modern day a house should also provide a level of comfort which reduces the need for engineered heating and cooling."
Some Perth developers, including Landcorp have banned dark, heat-absorbing roof colours in many of their new developments.
Steven Chu, the US Secretary of Energy and a Nobel prize-winning scientist, made headlines in 2009 when he gave a speech in London to say painting roofs white en masse would help reduce global warming by both conserving energy and reflecting sunlight back into space.
Dr Chu, the US government's longest-serving Secretary of Energy and the office's first and only Nobel Prize winner, was speaking before a global climate change summit when he said this simple "geo-engineering" measure could have a dramatic impact on the amount of energy used to keep buildings comfortable, as well as directly offsetting global warming by increasing the reflectivity of the Earth.
"Now you smile, but if you look at all the buildings and make all the roofs white, and if you make the pavement a more concrete-type of colour than a black-type of colour, and you do this uniformly... It's the equivalent of reducing the carbon emissions due to all the cars in the world by 11 years," British publication The Independent quoted.
Chu's comments were based on 2009 research from the government's national Berkeley Lab, which itself has won 13 Nobel prizes.
It has further completed a 2014 study finding that of black, white and "green" (vegetated) roofs, white roofs were the most cost-effective over a 50-year time span.
The idea is gaining momentum in Australia, with Melbourne University completing the 2011 Cool Roofs report in 2011 for the City of Melbourne to educate consumers on the use of more reflective roof paints.
Griffiths University, the University of Newcastle and Curtin University are also conducting research.
Submissions to the state government's Liveable Neighbourhoods review close on November 13.
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