The most important aspect of a cool pavement is its ability to reflect rather than absorb solar energy. Among the traditional pavement materials, concrete sets the standard as being the most reflective (high albedo), while black asphalt is the least reflective (low albedo) and most absorbent of solar energy. Typically NaturalPAVE XL Resin Pavement mixtures are formulated with light colored aggregate mixtures and consequently have high solar reflectance similar to concrete pavements. The differences in pavement surface temperatures between heat absorbent asphalt and highly reflective NaturalPAVE XL Resin Pavement can be significant. For example, utilizing an infrared thermometer during mid-August afternoon conditions (98°F air temperatures) and measuring areas of pavement subject to full day sun exposure, the following pavement surface temperatures were recorded at the zoo facility in Washington, D.C.
As part of its educational mission regarding sustainable living practices for the Las Vegas Valley, the Springs Preserve in Las Vegas, Nevada, has an outdoor exhibit displaying the difference in residual heat between objects that reflect solar energy and objects that are non-reflective and absorb solar energy. Using the lizard thermometer sculptures pictured at right, visitors can observe the temperature differences throughout the day between the reflective white lizard and the heat absorbent black lizard. The 119.4°F and 153.5°F temperatures displayed were recorded mid-morning on a summer day while the air temperatures were still under 100°F. They closely parallel the actual temperatures of reflective NaturalPAVE XL® Resin Pavement and heat absorbent black asphalt pavement surfaces in these same weather conditions, showing that NaturalPAVE XL Resin Pavement is the ideal surfacing for overlaying existing asphalt as well as new pavement installations.
The NaturalPAVE® XL Resin Pavement™ specimens pictured below have solar reflectance measurements that help in meeting or exceeding the minimum Solar Reflectance Index (SRI) of 29 to qualify as high albedo pavement materials. Use of such pavement materials reduces heat absorption and radiance as required for a LEED™ Rating System Point toward “Green Building” Certification from the USGBC as per Credit SS 7.1 (Heat Island Effect) for light-colored/high albedo pavement.