(Editor's note: This interview originally aired June 2019)
Las Vegas is the fastest-warming city in the country because of a changing climate and a heat island that grows with the community.
The city’s temperature has risen by 5.76 degrees since 1970, according to the environmental group Climate Central. A chief culprit is a growing heat island, the asphalt and other building materials that capture heat rather than reflect it.
Steffen Lehmann, head of the architecture school at UNLV, is an advocate for sustainable development. He says architects can fight back against the heat island with commonsense design elements.
One example: Landscaping.
“We need to be smarter about the planting of trees and the lack of shade,” he told State of Nevada. “I always say we need street planting programs where we plant trees along entire boulevards, urban greenery, vegetation not only green roofs the most effective is urban forest."
Lehmann said choosing drought-tolerant desert plants would mitigate the impact on Southern Nevada’s limited water supply.
He also said modern building materials absorb less energy and contribute less to heat islands.
“If you have brick, and concrete, and asphalt it stores terminal heat during the day and releases at night but if you have other materials that keep the city cool, it is much better," he said.
The materials need to address what is known as the Albedo Effect, which is the reflective value of objects either through color or material.
Lehmann gave the example of white buildings in the Bahamas. They reflect the heat, instead of absorbing it, which keeps the islands cooler.
While it makes sense to try to find materials that reflect solar radiation, Lehmann said the building industry has so far been behind on the topic.
“We have to challenge the building industry more and say, ‘hey, we need better materials and better products,’ they’re still sleepwalking. They’re not noticing the seriousness of this challenge,” he said.
Lehmann recommends rewriting of building codes with an emphasis on mandating more sustainable design elements. For instance, in California, buildings can no longer have black roofs and in Toronto, new buildings must have vegetative roofs.
“Heat waves are becoming the new normal,” he said and better design must be used to combat it.
Steffen Lehmann, director, UNLV School of Architecture
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