Study proves cool roofs will reduce energy consumption and district heating

A cost-benefit analysis of the implementation of a cool roof by the University of New South Wales (UNSW) found that the technology would reduce energy bills, lower indoor temperatures, decrease district heating and would improve the health of vulnerable populations.

The study looked at the uptake of cool roof technology in major Australian cities and was released a month after the New South Wales government abandoned an earlier policy commitment to phase out dark roofs. The policy would have reduced district heating and energy costs for new homes.

Cool roofs reflect more solar radiation than they absorb, so they stay cool in the sun.

The analyzes undertaken by the High Performance Architecture team from the School of Built Environment at UNSW Arts, Design & Architecture were part of a project funded by the Federal Ministry of Industry, Science, Energy and Resources (DISER).

The objective of the study was to assess the applicability and cost-benefit of using cool roof technology on buildings in Australia and to identify barriers to adoption.

Anita Lawrence, chair of high performance architecture at the UNSW School of Built Environment, said the study looked at the climate, social, economic and environmental impacts of implementing cold roofs in Australia.

“We used simulated climate modeling to understand conditions with and without cool roofs. The results showed that urban areas including western Sydney, Perth, Melbourne, Adelaide, Darwin and Brisbane had the most to gain from cool roofs,” Lawrence said.

“The need for cool roofs and other heat mitigation technologies should really be a priority. Otherwise, the cost of climate change in the next 10 to 15 years will be enormous.

The analyzes covered 17 building types, ranging from low-rise to high-rise, commercial to residential, and freestanding to apartment buildings.

Existing buildings with low levels of insulation have the most to gain in energy savings by installing cold roofs. Meanwhile, newer buildings with higher insulation levels have relatively less opportunity for energy savings compared to less insulated buildings, but there are still savings.

Research has shown that cold roof technology will significantly reduce cooling energy consumption. Indoor temperatures in residential homes would be reduced by up to 4 degrees Celsius with a cool roof, with hours exceeding 26 degrees Celsius reduced by 100 hours per summer compared to conventional roofs, which absorb sunlight rather than to reflect it.

If the whole of Sydney implemented cooling roofs, energy consumption for cooling residential and commercial buildings would decrease by up to 40% in total.

During the summer, a building in Western Sydney will require twice the energy to cool compared to the same building in Eastern Sydney.

In addition to energy savings for individual households, city-wide deployment of chilled roofs also provides collective cooling benefits for entire suburbs, according to the study.

With all Australian cities currently suffering from urban overheating, the implementation of cold roof and pavement technology will reduce temperatures in entire cities by up to two degrees Celsius during the summer period. This is because the heat is not transferred from the surfaces of the materials to the atmosphere.

Research also shows that using cool roofs citywide would reduce the maximum peak outdoor air temperature, which occurs at 2 p.m. each day, by an average of 1.5 to 2 degrees. Celsius during the summer.

Lower outside temperatures mean the air conditioning will work more efficiently. Along with reduced energy consumption, energy grids will experience reduced demand at peak times during the summer months, reducing emissions.

Cool roofs can reduce heat-related mortality by up to 25-30%.

Despite an established manufacturing sector producing cool roof materials nationally, a lack of legislation, policy support, accreditation standards and awareness is holding back the Australian cool roof industry, according to the research report.

If these barriers were overcome and cool roof technology was widely implemented, around 150,000 new jobs would be created in Australia, according to the study.

He discovered that the infrastructure is already there, as Australia has 10 different companies producing cool materials and exporting them around the world. Cool roof technology is widely used overseas.

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