Dusk is just as important as dawn. Those nighttime hours in the dark help provide a much-needed cooling effect that leverages our daytime highs, and minimizes the intensity of potentially lethal heatwaves in our cities.
The problem is that the cooling part of the equation is not happening as much anymore. It’s a phenomenon known as the ‘Urban Heat Island,’ and we built it ourselves.
Heat is absorbed, stored, and otherwise captured within concrete, black rooftops, tiles, and asphalt – the trappings of any city, really. A heat island is an area within a city, such as an airport, parking lot, or the Strip, that is significantly warmer than the surrounding suburbs.
Steffen Lehmann, a professor in the UNLV School of Architecture and director of the Urban Futures Lab, is focused on rethinking city architecture in the age of global warming. He actively researches this topic, which is slowly permeating the public consciousness globally.
“Las Vegas is the fastest-warming city in the nation,” said Lehmann. “It has already warmed more than three degrees Fahrenheit in the last 20 years, while the future is likely going to have heat waves that are hotter, more intense, and last longer.”
This affects much of the Southwest, including cities within Nevada, Arizona, Southern California, New Mexico, and Texas. But even cities in cooler climates to the north are not exempt from the heat island effect.
“By building with materials that absorb and store solar radiation, we’ve unwittingly turned many of our cities into baking ovens,” he said. “There’s a serious problem with the way that Las Vegas has been built.”
Because the heat is soaked into our very foundation, places such as Las Vegas do not have a fresh cooling period. It remains hot through the night and the solar radiation picks up momentum again at sunrise. And the increased temperatures can also contribute to dehydration and sickness, with increased health risks.
“Air pollution comes hand-in-hand with excessive heat,” said Lehmann. “A lot of people have asthma and breathing problems and they wonder why it’s happening to an increasing number of people. The trapped heat also traps pollution in the air from vehicles and other damaging emissions.”
Researchers have known about the absorption of solar radiation for about a century, though changing weather patterns and growing cities have made this a problem that cannot be ignored as architectural mistakes from the past catch up with us.
Fortunately, there are solutions: rooftop plants to keep the interior underneath cooler, integrating more vegetation or greenery into our parking lots to create continuous forms of shade, avoiding black asphalt and black tiles, and using brighter, light-reflecting rooftops.
“I am collaborating on a research study on parking lots right now, and we’re hoping to change the building code and the way parking lots are built,” said Lehmann. “We weren’t ready 25 years ago, but now we have all the technology for coating new heat-resistant roof products and materials – incorporating solar panels into facades and roofs. The science is out there, we have the knowledge, and it’s time to act. ”
These technologies have the potential to help make Las Vegas self-sustainable. Lehmann says the resort of tomorrow will ideally use daylight to its advantage by using the upcoming heat resilience tech to produce more energy than it consumes. Though this all counts on corporations and politicians putting pen to paper for urban sustainability.
“A lot of action plans, but very little action has happened so far. I think the timing is now, that we have to move forward, and looking 20 years down the road, I think we will have resolved many of the problems that we see today.”