Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New “Cool Roof Time Machine” Will Accelerate Cool Roof Deployment

20.04.2015

Standards body approves Berkeley Lab’s method to mimic natural soiling of roofing materials.

Cool roofs can help keep buildings cool, thus lowering the building’s energy use, while also mitigating the urban heat island effect by reflecting sunlight away from buildings and cities. But as cool roofs age and get soiled, how much of their reflectance do they lose?


Roy Kaltschmidt/Berkeley Lab

Berkeley Lab research associate Sharon Chen sprays roofing material with soiling mixture.

A collaboration led by scientists at Lawrence Berkeley National Laboratory (Berkeley Lab) has established a method to simulate soiling and weathering processes in the lab, reproducing in only a few days the solar reflectance of roofing products naturally aged for three years. Now this protocol has been approved by ASTM International, a widely referenced standards body, as a standard practice for the industry, and published as ASTM D7897-15.

“What we’ve created is essentially a cool roof time machine,” said Ronnen Levinson of Berkeley Lab’s Heat Island Group. “By reducing 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 the United States, but around the world.”

Roof reflectance is rated when new, and after three years of outdoor exposure. Because the ASTM standard has been endorsed by the Cool Roof Rating Council (CRRC), it is in turn accepted as part of California’s building code, specifically California's Title 24 Building Energy Efficiency Standards. Research is underway to adapt the method for use in China, India, and Europe.

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 “conditions” the material before soiling. Then a soiling apparatus developed at Berkeley Lab sprays a calibrated aqueous soiling mixture of dust, soot, particulate organic matter, and salts for about 10 seconds. After it dries, it goes back in the weathering apparatus for one more 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, and reproduced—in less than three days—the CRRC’s three-year aged values of solar reflectance.

The researchers devised different soiling mixtures to mimic site-specific features of three environments: a hot and humid climate (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 aged solar reflectance averaged over all three sites, which is the aged value reported by the CRRC on rated product labels.

A team of Berkeley Lab scientists and research associates, including Mohamad Sleiman, Hugo Destaillats, Sharon Chen, Thomas Kirchstetter, Haley Gilbert, Paul Berdahl, and Levinson, worked with Hashem Akbari at Concordia University, the CRRC, and more than 40 industrial partners to develop the protocol. The process was described in a paper in the journal Solar Energy Materials and Solar Cells last year.

Berkeley Lab and the CRRC will offer one-day courses on this practice on April 21 and 22. Representatives of 10 manufacturers, four independent testing laboratories, and several research institutions in Mexico and South Africa will come to Berkeley Lab to attend these fully subscribed workshops. Additional courses will be offered this summer to train researchers from China and India.

Funding for this research was provided by the Department of Energy, Energy Efficiency and Renewable Energy, Building Technologies Office.

# # #

Lawrence Berkeley National Laboratory addresses the world’s most urgent scientific challenges by advancing sustainable energy, protecting human health, creating new materials, and revealing the origin and fate of the universe. Founded in 1931, Berkeley Lab’s scientific expertise has been recognized with 13 Nobel prizes. The University of California manages Berkeley Lab for the U.S. Department of Energy’s Office of Science. For more, visit www.lbl.gov 

DOE’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov

Contact Information
Julie Chao
Science Writer
jhchao@lbl.gov
Phone: 510-486-6491

Julie Chao | newswise

Further reports about: ASTM Building Cool roofs Department Deployment Energy Laboratory Roof asphalt shingles ultraviolet light

More articles from Architecture and Construction:

nachricht New, forward-looking report outlines research path to sustainable cities
24.01.2018 | National Science Foundation

nachricht Magnetic liquids improve energy efficiency of buildings
16.01.2018 | Friedrich-Schiller-Universität Jena

All articles from Architecture and Construction >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Attoseconds break into atomic interior

A newly developed laser technology has enabled physicists in the Laboratory for Attosecond Physics (jointly run by LMU Munich and the Max Planck Institute of Quantum Optics) to generate attosecond bursts of high-energy photons of unprecedented intensity. This has made it possible to observe the interaction of multiple photons in a single such pulse with electrons in the inner orbital shell of an atom.

In order to observe the ultrafast electron motion in the inner shells of atoms with short light pulses, the pulses must not only be ultrashort, but very...

Im Focus: Good vibrations feel the force

A group of researchers led by Andrea Cavalleri at the Max Planck Institute for Structure and Dynamics of Matter (MPSD) in Hamburg has demonstrated a new method enabling precise measurements of the interatomic forces that hold crystalline solids together. The paper Probing the Interatomic Potential of Solids by Strong-Field Nonlinear Phononics, published online in Nature, explains how a terahertz-frequency laser pulse can drive very large deformations of the crystal.

By measuring the highly unusual atomic trajectories under extreme electromagnetic transients, the MPSD group could reconstruct how rigid the atomic bonds are...

Im Focus: Developing reliable quantum computers

International research team makes important step on the path to solving certification problems

Quantum computers may one day solve algorithmic problems which even the biggest supercomputers today can’t manage. But how do you test a quantum computer to...

Im Focus: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

Basque researchers turn light upside down

23.02.2018 | Physics and Astronomy

Finnish research group discovers a new immune system regulator

23.02.2018 | Health and Medicine

Attoseconds break into atomic interior

23.02.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>