Jessica Leigh Hester is a former senior associate editor at CityLab, covering environment and culture. Her work also appears in the New Yorker, The Atlantic, New York Times, Modern Farmer, Village Voice, Slate, BBC, NPR, and other outlets.
Just in time for summer: three smart ways cities, and the people who live in them, deflect the sun’s rays.
On really hot afternoons in crowded cities, the pavement seems to sweat and sizzle. As the sun beats down on tarry roads, the asphalt sometimes feels like it’s singeing your shoes and licking at your ankles.
Chalk that up, in part, to the urban heat island effect. Dense cities, packed with steel, cement, and glass, retain more heat than rural areas. The Environmental Protection Agency estimates that cities with more than 1 million residents can have an annual mean air temperature nearly six degrees warmer than surrounding areas. On a given evening, that difference can be as much as 22 degrees.
Here are three smart ways that cities—and the people who live in them—can deflect the rays.
Permanent or pop-up shelters offer a break from the sun. Each year, Figment NYC and a handful of other architectural organizations issue a challenge to design a temporary structure on Governors Island, a former military base between Manhattan and Brooklyn in New York Harbor. The island’s expansive grassy knolls are hard hit by the sun, and the pavilions double as event spaces and cool-off spots.
One of the summer 2015 pavilions, designed by Izaskun Chinchilla Architects, makes use of busted umbrellas, warped bicycle wheels, and battered stools. Portions of the shelter can be transformed into smaller shields from the elements once the installation is dismantled in September, reports Architectural Digest.
This season’s other pavilion, designed by architects at BanG Studio, is part of a project to boost the oyster population in New York’s waterways. This structure, made from marine line and cinder blocks, will eventually be plunged into the salty water, where activists from the Billion Oyster Project hope it will become a home for the mollusks. (Their goal: Distribute one billion live oysters across 100 acres of reefs by 2030.) In the meantime, non-bivalves can enjoy the shade under the cages.
Leafy canopies offer respite from rays. The EPA reports that shaded surfaces, for example, may be 20 to 45 degrees cooler than the hottest unshaded areas. According to the EPA, trees and vines are especially useful heat busters when they obscure west-facing windows or portions of a building’s roof. And by keeping people cool, urban forests decrease the blasting of ice-cold air conditioning, reducing energy use.
The Age, a newspaper in Victoria, Australia, reports that Melbourne’s city council plans to strategically increase the proportion of the city shaded by trees, reaching 40 percent coverage by 2040. One councilman estimated that this could lower local temperatures by as much as five degrees.
Melbourne’s already pretty shady. The map below plots the portions of the city that are covered by 70,000 municipal trees, measured by a series of aerial photos. The dark areas correspond to places with the most shade. Unsurprisingly, these concentrations are within the boundaries of city parks.
Though planting trees is a fairly substantive investment, a study in the Journal of Forestry found that it pays off handsomely. Researchers compared the costs and returns of planting and maintaining trees in five cities in the American Southwest: Fort Collins, Colorado; Cheyenne, Wyoming; Bismarck, North Dakota; Berkeley, California; and Glendale, Arizona. The authors concluded that “benefits returned for every dollar invested in [tree] management ranged from $1.37 to $3.09.”
So your city isn’t leafy or full of pavilions? Pull on a hat. Cotton versions from Coolibar deliver a double whammy. The wide four-inch brim keeps rays out of your eyes, delivering portable shade. Plus, the whole thing is made with UPF 50+ fabric, which blocks 98 percent of UVA/UVB rays. (The Skin Cancer Foundation recommends hats with a brim of at least 3 inches.) In contrast to photoprotective clothing, the average t-shirt delivers a UPF of 10.