Nav: Home

The 'time machine' that replicates 3 years of weather in 3 days

March 22, 2017

Montreal, March 22, 2017 -- Climate change is wreaking havoc on the environment. While the main culprit is carbon emissions, urban heat islands -- exacerbated by dark roofs and pavements -- make the effect of global warming even worse on the urban dwellers.

One solution to the problem is cool roofs: surfaces made of light, reflective materials. By keeping buildings cool, these roofs lower energy use, while at the same time reflecting sunlight away from buildings and cities.

But like anything exposed to the elements, cool roofs age and become dirty over time. This natural wear and tear causes them to lose some of their reflective abilities. The question is, how much are they affected? And can this loss of performance be slowed?

An engineering team at Concordia has collaborated with researchers at the Lawrence Berkeley National Laboratory in California to simulate the weathering of cool roofs in the lab. In just a few days, they can now reproduce three years of aging for roofing products in order to test their solar reflectance.

ASTM International, a widely referenced standards body, recently approved this new method as a standard practice for the industry. It was also published in the journal Solar Energy Materials and Solar Cells.

"What we've created is essentially a cool roof time machine," says Hashem Akbari, professor in Concordia's Department of Building, Civil and Environmental Engineering.

"By reducing the product rating time to three days from three years, our new ASTM standard practice will speed the introduction of high-performance cool roofs not only in Canada and the United States, but around the world."

The laboratory practice involves putting a piece of the roof material in a commercial weathering apparatus, which exposes the material to cycles of heat, moisture and ultraviolet light for one day. This process conditions the material to behave as if it has been exposed to the elements for a much longer period of time.

Next, researchers use a soiling apparatus to spray a specially calibrated soiling mixture of dust, soot, particulate organic matter and salts onto the roof material for about 10 seconds. After it dries, the material goes back into the weathering apparatus for another day to simulate the cleaning effects of dew and rain.

This method was applied to 25 different roof products, including single-ply membranes, coatings, tiles and asphalt shingles.

The researchers also devised different soiling mixtures to mimic site-specific features of three environments: a hot and humid climate (to mimic Miami, Florida), a hot and dry climate (Phoenix, Arizona) and a polluted atmosphere in a temperate climate (Cleveland, Ohio).

A fourth soiling mixture was devised to replicate the solar reflectance averaged over all three sites.

"For every location, we found that our new process is about 400 times faster than natural exposure, costs about 80 per cent less for testing a single product, can facilitate rapid prototyping and can avoid three years of lost sales worth $4.5 million to $9 million per product," says Akbari. "It's a time-saver and a cost-saver."

The Cool Roof Time Machine was recently recognized by R&D Magazine, which awarded the project one of its R&D 100 Awards, given to the 100 most significant technologies and services introduced in the previous year, as judged by an independent panel.
Partners in research: Akbari worked with a team of of Berkeley Lab scientists and research associates, including Mohamad Sleiman, Hugo Destaillats, Sharon Chen, Thomas Kirchstetter, Haley Gilbert, Paul Berdahl and Ronnen Levinson, as well as the Cool Roof Rating Council (CRRC) and more than 40 industrial partners, to develop the protocol. Funding for this research was provided by the US Department of Energy, Energy Efficiency and Renewable Energy, Building Technologies Office.

Related links:

Department of Building, Civil and Environmental Engineering

Lawrence Berkeley National Laboratory

Hashem Akbari

Media contact:

Cléa Desjardins
Senior advisor, media relations
University Communications Services
Concordia University
Phone: 514-848-2424, ext. 5068
Twitter: @CleaDesjardins

Concordia University

Related Climate Change Articles:

A CERN for climate change
In a Perspective article appearing in this week's Proceedings of the National Academy of Sciences, Tim Palmer (Oxford University), and Bjorn Stevens (Max Planck Society), critically reflect on the present state of Earth system modelling.
Fairy-wrens change breeding habits to cope with climate change
Warmer temperatures linked to climate change are having a big impact on the breeding habits of one of Australia's most recognisable bird species, according to researchers at The Australian National University (ANU).
Believing in climate change doesn't mean you are preparing for climate change, study finds
Notre Dame researchers found that although coastal homeowners may perceive a worsening of climate change-related hazards, these attitudes are largely unrelated to a homeowner's expectations of actual home damage.
Older forests resist change -- climate change, that is
Older forests in eastern North America are less vulnerable to climate change than younger forests, particularly for carbon storage, timber production, and biodiversity, new research finds.
Could climate change cause infertility?
A number of plant and animal species could find it increasingly difficult to reproduce if climate change worsens and global temperatures become more extreme -- a stark warning highlighted by new scientific research.
Predicting climate change
Thomas Crowther, ETH Zurich identifies long-disappeared forests available for restoration across the world.
Historical climate important for soil responses to future climate change
Researchers at Lund University in Sweden, in collaboration with colleagues from the University of Amsterdam, examined how 18 years of drought affect the billions of vital bacteria that are hidden in the soil beneath our feet.
Can forests save us from climate change?
Additional climate benefits through sustainable forest management will be modest and local rather than global.
From crystals to climate: 'Gold standard' timeline links flood basalts to climate change
Princeton geologists used tiny zircon crystals found in volcanic ash to rewrite the timeline for the eruptions of the Columbia River flood basalts, a series of massive lava flows that coincided with an ancient global warming period 16 million years ago.
Think pink for a better view of climate change
A new study says pink noise may be the key to separating out natural climate variability from climate change that is influenced by human activity.
More Climate Change News and Climate Change Current Events

Top Science Podcasts

We have hand picked the top science podcasts of 2019.
Now Playing: TED Radio Hour

Accessing Better Health
Essential health care is a right, not a privilege ... or is it? This hour, TED speakers explore how we can give everyone access to a healthier way of life, despite who you are or where you live. Guests include physician Raj Panjabi, former NYC health commissioner Mary Bassett, researcher Michael Hendryx, and neuroscientist Rachel Wurzman.
Now Playing: Science for the People

#544 Prosperity Without Growth
The societies we live in are organised around growth, objects, and driving forward a constantly expanding economy as benchmarks of success and prosperity. But this growing consumption at all costs is at odds with our understanding of what our planet can support. How do we lower the environmental impact of economic activity? How do we redefine success and prosperity separate from GDP, which politicians and governments have focused on for decades? We speak with ecological economist Tim Jackson, Professor of Sustainable Development at the University of Surrey, Director of the Centre for the Understanding of Sustainable Propserity, and author of...
Now Playing: Radiolab

An Announcement from Radiolab