Energy Star Certified Cool Roof Coatings

Pacific Northwest Cool Roof Applications

Save money while protecting the environment – that is what energy efficient roofing with a cool roof accomplishes. Utilizing the right coating product can enhance heat reflectivity and energy efficiency. Similar to wearing light-colored clothing on a hot day, roof coatings provide solar-reflective surfaces that help maintain lower roof temperatures.

During warmer summer months, temperatures can reach 170° degrees F on traditional dark roofs, such as a low-slope black asphalt roof, while they can drop to -20° degrees F during winter in northern and elevated regions. Much of the heat generated by absorbing the sun’s ultraviolet (UV) radiation transfers to the building interior, significantly impacting energy consumption.

Cool Roofing solutions, including ENERGY STAR certified roofs, utilize qualified roof coating materials that mitigate the need for air conditioning in buildings, potentially reducing energy bills by up to 50 percent. The Cool Roof Program defines specific standards for solar reflectance, three-year aged maintenance of reflectivity, and emissions in roof coating systems. Reflectivity indicates the percentage of the sun’s heat a roof keeps off a building, while emissivity reflects the percentage of heat a roof releases from a building.

Lighter colored (white) roof coatings reflect the sun’s UV rays and heat, lowering the temperature of the roof by as much as 100° degrees F.

The most commonly used cool roof coatings over sprayed polyurethane foam (SPF) and other roof deck surfaces are light or white-colored. The most common types include:

Acrylic – Acrylic coatings are typically water-based and are a staple in the market due to their cost-effectiveness and environmental friendliness. They provide high reflectivity, effectively cooling the roof, and can be elastomeric, allowing for temperature fluctuations without compromising the coating. Overall, acrylic coatings help reduce cooling costs while extending the service life of a roof by protecting it from UV exposure.

Silicone – Silicone coatings are also prevalent, particularly on spray polyurethane foam (SPF) roofs due to their permeability. They are ideal for areas with extreme temperature ranges and frequent UV exposure. After applying the base coat, a slick surface is created, upon which only another layer of silicone coating can be applied as a recoat.

Urethanes – Polyurethane coatings offer a highly durable surface that shields the roofing system against various conditions. Urethanes generally possess higher tensile strength, resisting expansion and contraction of the roof system. This feature is crucial in high-stress areas of the roof, such as wall flashings or around penetrations. Urethane coatings can be derived from either aliphatic or aromatic formulations. Aliphatic urethane coatings provide long-term UV protection, while aromatic urethanes tend to affect film integrity over time due to potential chalking from UV exposure.

Polyurea – Polyurea coatings consist of 100% solids formed through a reaction between an isocyanate and an amine resin, which can be aromatic or aliphatic. These coatings are easy to apply, curing rapidly without being affected by moisture or temperature. Polyurea adheres smoothly to virtually any roof substrate, enhancing the roofline as well.

Urban Heat Zones / Islands

Installing cool roofs in cities can significantly contribute to urban heat reduction. Urban Heat Zones are caused by numerous large dark-colored roofs in urban areas that can reach extremely high temperatures. This macro heat effect from hot buildings and pavement leads to smog, increased energy consumption, and discomfort for building occupants. A cool roof can help protect the environment and reduce costs. Many states offer utility discounts and rebates to building owners who install ENERGY STAR certified roofs.

Approvals & Specifications

It is virtually impossible to ascertain the performance of two pails of roof coating simply by looking at them. Therefore, specific guidelines have been established for the testing and approval of liquid-applied roof coatings, providing a yardstick to measure all products. Products that meet these recognized standards display that information on their labels. Facility owners and managers should look for such markings when evaluating coatings to meet specific needs, as some markings indicate compliance with standards or having received approval from certifying testing organizations.

Among the critical standards is the American Society for Testing and Materials (ASTM) D 6083. This standard measures coatings against specific performance and physical characteristics, including viscosity, elongation, tensile strength, accelerated weathering after 1,000 hours of exposure, permeance, water swelling, adhesion, tear strength, and low-temperature flexibility. Meeting these comprehensive standards should guide managers toward an excellent roofing product.