When it’s scorching hot in downtown Dallas, it can be several degrees cooler in the suburbs and relatively pleasant in rural areas.

Blame it on Dallas’ urban heat island effect: heat produced by densely concentrated people, vehicles and energy use.

And when the city’s hot, you can bet the roofs are on fire. That’s why “cool roofs” are among the initiatives the city of Dallas has implemented to reduce the urban heat island effect.

Cool roofs are designed to reflect, rather than absorb, the heat and can even help cool the inside of a building, according to the U.S. Green Building Council. Since 2013, the city requires all new construction in Dallas to have cool roofs as part of the Green Building Ordinance. 

These measures aren’t just green but also cost-effective.

“They have the potential to reduce emissions in one of our biggest sectors — buildings and energy — in a way that cuts energy costs to the consumer,” said James McGuire, director of the Dallas Office of Environmental Quality and Sustainability.

New buildings in Dallas must: use roofing materials that reflect solar heat on at least 75% of the roof’s surface; have a vegetated roof that covers at least 50% of the area; or use a combination of the two, according to requirements by the Green Building Council.

A 2014 study found that in metropolitan areas cool roofs could help temperatures drop by about 3 degrees.

Setting an example

As buildings comply with Dallas’ cool roof requirements, others are going beyond that by seeking certification for Leadership in Energy and Environmental Design. LEED is a rating system that certifies buildings with green features that are energy and resource efficient and good for the environment. 

The Perot Museum of Nature and Science, which has LEED gold status, boasts a “living roof” that — in addition to mitigating the urban heat island effect — is designed to catch rainwater and condensation from the building’s mechanical equipment, according to Mike Spiewak, the museum’s vice president of exhibitions.

“The mission of the Perot Museum is to inspire minds through nature and science,” Spiewak said. “The museum’s ‘living roof’ is more than just a visually interesting shelter, it also serves as an educational illustration of the diverse biomes of Texas, from the deserts of West Texas to the prairies of Central Texas.”

The museum’s roof filters water into cisterns that hold 50,000 gallons used to irrigate the grounds and to serve other nonpotable water needs such as toilet flushing, Spiewak said. 

The Trinity River Audubon Center in southeast Dallas also features several green features, including a vegetated roof on its administrative wing, water-efficient landscaping, paving to control stormwater and other efforts that gave it a LEED certification. 

Other buildings, like Victory Block G at 2370 Victory Avenue and AMLI Fountain Place at 1800 Field Street, are taking LEED-based approaches without the official certification. 

Going beyond 

While Dallas requires all new construction to have cool roofs, New York City took it a step further by providing existing buildings with cool roofs through a program called NYC CoolRoofs. 

The initiative installs cool roofs for free or at a low cost to nonprofits, community or recreational centers, schools, hospitals, museums and cultural centers, and co-op housing. Since 2009, more than 5 million square feet of rooftops have been coated throughout the city, according to New York’s office of sustainability.  

Other cities are going beyond roofs to cool things down. Los Angeles, for example, in 2017 began painting black roads white with a cool pavement treatment. The treatment can keep things 10 degrees cooler on a summer afternoon, according to the Los Angeles Department of Public Works.

The cooler roads are costly, however, with a price tag of $40,000 per mile, according to Business Insider. 

In Mexico City, hundreds of highway pillars are being turned into vertical gardens through a project called Via Verde. The project aims to help regulate temperature, reduce air pollution, lessen noise and even decrease stress for residents of the Mexican capital.