Dressing for a walk on the beach on a hot day? You’d probably choose to wear white or light colors to stay as cool as possible. That’s the same logic behind the choice to use ultrawhite reflective filler in roof coatings. Bright white surfaces in dense urban environments can help cool buildings and neighborhoods, making them more comfortable and lowering energy costs.
Cost-effective heat mitigation solutions are a hot topic in the building and construction industry. This blog will examine the benefits of cool roofs and the advantages of using CRISTOBALEX™ ultrawhite reflective filler from Covia® in cool roofing and other applications. Learn how this product is engineered for efficiency and improves sustainability.
From Cristobalite to Ultrawhite
CRISTOBALEX is a specialty silica blend that is primarily composed of cristobalite. It starts with high-purity spherical quartz grains, which are thermally treated. Covia’s proprietary process alters the mineral’s structure and enhances its whiteness.
Covia produces CRISTOBALEX at our specialty manufacturing facilities in Fort Smith, Arkansas. After processing, CRISTOBALEX is micronized to 325 (50-55 µm) and 400-mesh (40-45 µm) top-size. Scott Van Remortel, Applications Technology Manager at Covia, explains how Covia’s process takes advantage of cristobalite’s natural properties. “As you heat the silica, it increases in volume and becomes whiter. We take a ground silica material with color impurities, and through this process, the color becomes very, very white, and the structure expands and stays locked in an open position.” These properties are valuable in many types of applications, but especially for creating cool roof coatings that reflect solar energy and reduce building temperatures.
Heat Islands and Cool Roofs
Urban heat islands exist in concentrated built environments in warm climates where heat is absorbed by buildings, leading to elevated temperatures. One driver of the heat is the abundance of surfaces, from roofs to sidewalks and roadways, that absorb solar energy and emit it into the environment. Large buildings further reduce airflow and trap solar and thermal radiation. Vehicles and air conditioning systems release heat, further contributing to the heat island effect.
Cool white elastomeric roof coatings with reflective fillers like CRISTOBALEX help to mitigate the heat island effect by reducing the amount of heat buildings absorb. According to the Cool Roof Rating Council, cool roofs can have economic and environmental benefits. Cool roofs have high solar reflectance, the ability to reflect the sun’s energy, and thermal emittance, a measure of how efficiently the roof radiates heat. This helps to reduce the amount of heat trapped in the building below and, therefore, reduces the energy and associated costs that would go into cooling the building.
Research suggests that increasing solar reflectance of roofs, walls, and pavements can lower a building’s surface temperature by more than 10°F and the corresponding air temperature by up to 1°F. Even a small degree of cooling can increase comfort and provide economic benefits. Furthermore, the benefits of implementing such heat mitigation strategies far outweigh the costs. One analysis of more than 1,600 cities found that moderate use of cool roofs and pavements can provide a 12:1 benefit compared to the related costs of implementing these solutions.
Boosting Solar Reflectance, Lowering Temperature
“When you measure solar reflectivity, you’re taking into consideration what the human eye can’t see,” says Van Remortel. “CRISTOBALEX increases both the visual whiteness of the coating, measured as the L* color component, in other words, how bright it looks, and the solar reflectance, which measures how much heat it reflects or how warm or cool the surface feels.”
CRISTOBALEX, which complies with ASTM D6083 – Type II for Cool Elastomeric Roofs, is especially effective at increasing solar reflectance. Typically, to achieve high solar reflectivity, you would need a specialized white pigment like titanium dioxide (TiO2). CRISTOBALEX creates the opportunity for titanium dioxide offset, meaning less of the costly pigment is needed to achieve the same degree of reflectance.
Staying Cool With Less Titanium Dioxide
Because CRISTOBALEX produces a synergistic effect with titanium dioxide, it is possible to achieve higher measures of brightness and solar reflectance while using less pigment. Test results show that, for 80% solar reflectivity and above, 20 to 30% less TiO2 is required with CRISTOBALEX, compared to the same volume of a cool white elastomeric emulsion with calcium carbonate.
“You can reduce titanium dioxide between 20 and 40% and replace other extender pigments and fillers like calcium carbonate with CRISTOBALEX,” says Van Remortel. “It allows titanium to do what it’s supposed to do. Fillers with more impurities are not as effective because those impurities impede the ability of the titanium to reflect light. CRISTOBALEX optimizes the efficiency of the titanium and offers potential titanium dioxide offset for cost savings.”
Reduced Density of CRISTOBALEX
The low density of cristobalite is another property that gives CRISTOBALEX significant advantages over conventional fillers. Due to the expanded structure of cristobalite, the density of CRISTOBALEX is 15% to 20% lower compared to conventional fillers like calcium carbonate. As Van Remortel notes, “Other minerals, like barite, are also highly reflective, but the density is much higher. A 5-gallon can of coating using barite might weigh 70 pounds.”
The lower density of CRISTOBALEX translates to a lower-weight material and a smaller energy footprint when it comes to coating or paint production and transportation. “From handling materials going into the paint batch, post-production shipping, and the contractor handling buckets on the job site, the lower density and weight makes a significant difference for energy output and presents an ergonomic advantage,” Van Remortel says.
Beyond Cool Roofs
CRISTOBALEX isn’t limited to cool white elastomeric roof coatings. The high solar reflectivity it imparts makes it a natural choice for pigmenting concrete when building playgrounds, spray parks, parking lots and sidewalks in hot climates. Van Remortel says this makes a big difference in places like Phoenix. “Cool white concrete is a game-changer in places with extremely high temperatures because it can cool playground surfaces, walkways and roadways, lowering the temperature so people can spend more time outside.”
In addition, CRISTOBALEX’s high purity, low density, and brightness add durability and superior UV resistance, making it a cool solution for south-facing vertical walls and ultrareflective traffic paint. With its potential to increase the efficiency of titanium, it can impart economic advantages while being used to create high contrast and highly durable markings for airstrips, roadways and parking lots.
Covia’s Commitment to Sustainability and Innovation
Covia is dedicated to creating innovative and sustainable solutions that empower our customers to address complex environmental challenges. CRISTOBALEX is a prime example. As a highly reflective filler for cool elastomeric roof coatings, CRISTOBALEX can increase a project’s efficiency while reducing its carbon footprint. Covia is proud to play a role in reducing heat islands and making buildings and communities more comfortable and sustainable.
Partner with Covia
Beyond providing innovative and sustainable solutions, we are also committed to exceptional customer service. Covia is your trusted partner and has been delivering high-quality mineral solutions for more than 25 years. You can rely on our expertise, robust supply chain, strategic distribution network, large-scale production capabilities, impeccable logistics, and reliable delivery.
How can we help with your next project?
Contact us today to learn more about our sustainable mineral solutions, including the transformative benefits of CRISTOBALEX for cool roofs and more.
