Keeping cities cool from the top down

By Emma Peterson. 

How CertainTeed’s CoolStar line is helping combat rising urban temperatures.  

Rising temperatures around the world are causing issues for both individuals’ health and our communities as a whole. According the to the Bureau of Labor Statistics, between 2011 and 2023, 423 people had died due to workplace heat exposure and “an average of 2,700 cases involving heat illnesses lead to days lost at work.” Beyond the tragedy of loss of life and injury, it is estimated by that the U.S. loses $100 billion annually due to “heat-induced declines in labor productivity.” 

So, what can we do about that? One solution is to design cooler cities. 

Building a cooler city 

 A key to creating a more thermally resistant built environment is incorporating cool roofing. “Cool roofs” are roofing systems that reflect solar energy that comes from the sun and emit any remaining heat that is absorbed, leading to more energy efficient buildings and significantly cooler interiors. The Cool Roof Rating Council (CRRC) explains, “Cool roofs literally stay cooler and reduce the amount of heat conducted into the building below. If a building does not have air conditioning, this keeps the building cooler and a more constant temperature. If a building has air conditioning, the equipment does not have to work as hard.” 

How does one design a roof that reflects solar energy? To answer that question, we sat down with John Schultz, the commercial roofing district sales manager for CertainTeed.  

Designing a cool roof 

In his role at CertainTeed, John has worked a lot on the launch of a product line called CoolStar. He explained, “We’re building a family of products. Our first product is the Flintlastic® GTA CoolStar® and now we have our CoolStar® Ultra, both of which are torch-down products.” 

These products have existed in the CertainTeed portfolio for decades and have become contractor favorites. When released as a part of the CoolStar line, the products were improved to boost performance. John explained, “It's the exact same technology. We just changed the granules. So, if you’re a contractor using it, it is the same product you know and love. Your crews already know where to have their torch and how to apply it.”  

So, what changed with the granules? The CertainTeed team designed the CoolStar family of products with “Naturally occurring aggregate processed to bright white granules that are 100% opaque to UV radiation, protecting the asphaltic membrane from UV degradation while maintaining granule adhesion with superior solar reflectance.” 

By the numbers 

The results of this engineering and design feat are powerful coatings that not only deliver durable performance but also sustainability. When looking at cool roofing products, the CRRC highlights two characteristics that determine the roof’s sustainability – solar reflectance and thermal emittance. Solar reflectance is how much sunlight is reflected away from the roof, and thermal emittance is how much heat a roof can release. These properties are measured on a “scale from 0 to 1, where 1 is 100% reflective or emissive.” 

On this scale, CertainTeed’s CoolStar products perform very well. Their CoolStar Ultra is considered highly reflective with a score of 0.73 when installed (maintaining it to 0.68 over three years of on the roof aging) and highly emissive with a score above 0.90.  

The big picture 

Ultimately, CertainTeed’s CoolStar family of products is a huge step towards a more sustainable and healthier built environment. By building upon their existing quality products, they have created an efficient and sustainable way to reduce urban heat without sacrificing durability. The drive to do this all comes back to CertainTeed and their parent company Saint Gobain’s dedication to being a good steward of the environment. John explained, “One of our goals is to have a net 0 carbon target by 2050. How are we going to get there? By making our products more efficient with releases like the CoolStar line.” 

Learn more about CertainTeed’s Flintlastic® GTA CoolStar® and now we have our CoolStar® Ultra online.