The roof isn’t the only part of the building exterior where reflective and emissive materials can help cut energy demand, according to an article from Building Operating Management on the FacilitiesNet website.
The logic behind increased use of cool walls is best understood when considering multi-story buildings particularly found in urban locations.
“In multi-floor buildings, a cool roof affects the HVAC energy use of only the top floor while cool walls influence the HVAC energy use of every above-grade floor," according to Ronnen Levinson, staff scientist and leader of the Heat Island Group at Lawrence Berkeley National Laboratory.
"Thus all else being equal, we expect cooling savings and heating penalties from cool walls to be greater than those from a cool roof when the building has a low ratio of roof area to net wall area.”
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