If you select the color of the roof in your house, you can influence your electricity bills and comfort as well as the planet as a whole.
From above in heaven and downwards, the roofs are a large part of the 2 to 3 percent of the earth's surface covered by urban areas.
And the way the large -built surface absorbs and reflects light and solar radiation from the sun can not only influence the ambient temperatures in our suburbs, but also global warming.
Black roofs hardly reflect light and absorb a lot of solar radiation, which means that they catch a lot of heat during the day – what makes your house and your neighborhood hotter.
This heat is emitted at night when the ambient temperature cools down and gets stuck in the earth's atmosphere.
The expansion of the suburb into the west of Sydney, like Marsden Park, saw houses with mainly dark roofs. ((Google Earth: Aerometrex/Maxar Technologies/CNES/Airbus)))
Lighter colors, on the other hand, can reflect about 80 percent sunlight during the day and absorb less radiation.
In commercial development there is an even higher class from “super cool” materials used on roofs, from synthetic polymers to colors.
These products have over 95 percent reflection assets, and a group of US scientists even made a color so white that it reflects about 98 percent of the sunlight.
At this speed, so much solar radiation is broadcast back into space, behind the atmosphere, it actually has a cooling effect and makes the treated surface several degrees cooler than the surrounding air temperature.
This is known as a passive day of the day (PDRC) and can lead to a surface under the ambient temperature is 7 to 8 degrees Celsius.
The passive day of the day is a method of using surfaces that can be heated both light and again in space and used to cool down buildings. ((Wikimydia: Niaxolotl, PDRC, PDRC, CC BY-SA 4.0)))
There are many research results in PDRC materials because it offers a way to cool our buildings and planets without using energy for things like air conditioning systems, which can lead to a warmer climate.
If you could only cover one Percent of the global interface in these reflective materials was theorized that it would compensate for many of the people caused by humans.
Why don't we do that exactly?
Cool in summer, warm in winter
So far, PDRC materials have mainly been used in high-rise buildings, but there are disadvantages in the introduction of houses with low buildings.
Costs and scalability are a problem. Another is the fact that PDRC materials are white or silver and can dazzle their high reflection.
The main problem, however, is that PDRC materials are so effective when cooling that your house can become colder in winter, which means that you then use heaters.
The architectural engineer Hassan Khan and his colleagues at Unsw have worked on a different approach to the problem by adding a fluorescent colored film about PDRC materials.
These materials are referred to as “passive colored radiation coolers”.
The researchers tested the surface temperatures of passive radiation coolers. ((Delivery: Hassan Khan)))
In a recently carried out study under the direction of Dr. Khan was found that several color configurations (using orange, red and green) have similar cooling effects such as white PDRC materials under hot and dry conditions and at the same time maintain some warmth in winter.
The results of the study were published in the Journal solar energy materials and solar cells examined by experts.
It was found that one of the orange cooler tests in Alice Springs is the same with a PDRC reference sample.
In the meantime, the tests in Sydney in winter led orange, green and red configurations to temperatures of up to 3.8 ° C, 3.6 ° C and 5.5 ° C hotter than a PDRC.
Dr. Khan said fluorescent dyes were added to the study for a synthetic film, but that researchers were able to develop other forms of the “super cool” material.
“Now we'll bring with us [coloured super-coolers] In a paint shape and these colors can be applied to any surface, “he said.
Since the study was carried out, the selection of super cooling colors has expanded by purple and different red tones.
Dr. Khan said it was the team too Work on a potential black option.
“These black surfaces will not absorb the radiation as conventional black surfaces absorb. They will deliver much better results,” he said.
The use of fluorescence dyes was Also cheap, added Dr. Khan added, which made the technology more scalable.
The researchers are now working on improving durability and extending the lifespan of the fluorescent materials from about five years to over 15 years.
But beyond the technical hurdles, cool roofs are another challenge.
No Australian standard for a “cool roof”
While Europe and the USA have cool roof councilors who certify the stressed performance of commercial products, there is currently no standard for a cool roof in Australia.
Mat SantaMouris, professor of high -performance architecture at unsw, said that he tried to push for an Australian version without success.
“We need certified products. It's very easy,” said Professor Santamouris.
“Everything is certified with stars, why not the color? Why not the other materials?
“As soon as the materials are certified, customers have guaranteed results.”
In Australia there is no standard for roof products in Australia, but this does not necessarily mean that roof materials are not taken into account in new buildings.
Most of Australia has now taken over updated national building code, in which the houses have an energy rating with 7-star stars.
And some states such as South Australia and Victoria consider wider bans on dark roofs.
So what should you do if you want a cooler roof?
Elham Monavari, a sustainability expert at Green Building Council Australia, said that if you want to choose a normal cold roof, the color is still a simple starting point.
Tiles and steel are the most common roof materials for home buildings in Australia. Ms. Monavari said that there was usually information about the solar reflection assets for steel products.
“The higher this value, the better the roof is to reflect on the heat,” she said.
Ms. Monavari ultimately said that a cool roof was “low -hanging fruits” from a perspective of sustainability at home.
“When I say low -hanging fruits, there are usually no additional costs for the materials,” she said.
“It will be a bit of a child's game. Why shouldn't you do something that makes you more comfortable inside [your home]? “