‘Cool walls’ energy efficiency pilot credit scheme launches in US

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The US Green Building Council (USGBC) is investigating the integration of sunlight reflecting ‘cool walls’ in its building ratings.

Sunlight reflecting ‘cool walls’ are known to improve building energy efficiency – and lower energy costs – by lowering the heat gain in buildings. In turn they have the potential to play a key role in ‘cooling’ the heat islands prevalent with high rise buildings in cities.

With a view to the inclusion of reflective walls in its Leadership in Energy and Environmental Design (LEED) ‘green’ ratings for buildings, the USGBC has initiated a pilot credit scheme for the installation of such walls in new homes, schools and commercial buildings.

Under the scheme, buildings that satisfy specific cool wall requirements will earn an innovation point in LEED. After a trial period, USGBC will decide whether to add the pilot credit to its permanent library.

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“LEED has long recognised the heat island reduction benefits of cool roofs and pavements. This pilot credit also acknowledges the urban cooling that can be delivered by reflective walls,” says Ronnen Levinson, leader of Berkeley Lab’s Heat Island Group, which wrote the pilot credit scheme.

“Choosing cool wall materials for new construction or routine repainting is an easy and affordable way to make our cities cooler and safer while lowering your energy bill.”

The scheme requires at least 75% of the building’s gross exterior wall area to be surfaced with a cool wall material, which is opaque to sunlight and reflects at least 60% of the sunlight among other specifications.

Such materials include solar-reflective paint or cladding. Vegetated walls also may qualify as cool walls for the purposes of pilot credit compliance.

According to researchers at Berkeley Lab, cool walls are also gaining acceptance as a way to reduce energy costs and greenhouse gas emissions in buildings. In warm cities across the US from Miami, Florida, to Albuquerque, New Mexico and all across California, cool walls could provide energy savings and emissions reductions in homes, offices and stores comparable to those from cool roofs.