Light-colored roof coatings like those offered by Conklin are commonly used in climates that use cooling because dark colors absorb heat, and light colors reflect heat. Roofs have intense solar heat gain (energy) because of their relatively flat exposure to the sun. The intense solar gain raises the temperature of the roof membrane (sometimes near 200F), which increases cooling load in the building and shortens life of the roof. You can lower cooling costs and extend roof life by hiring a certified professional roofing contractor to install a light colored coating (also called cool-coating system) over an existing roof.
Light-colored roofs do reflect some of the incident solar energy. A term used as a measure of reflectivity and absorptivity is albedo. The higher the albedo of a surface, the less energy it absorbs, and the cooler a temperature it maintains. Typical built-up flat roof surface materials such as modified bitumen and tar and gravel (with albedos from 0.10 to 0.20) can absorb over 70% of the solar energy that falls on them and can reach temperatures of 170–200F.
Ultraviolet (UV) light rays can penetrate roofing membranes and cause accelerated chemical degradation of the roofing materials. High-performance elastomeric white reflective coating systems contain substantial levels of UV-blocking pigments that keep heat away. A cool surface reflects the sun’s ultraviolet rays and slows down roof aging. Roofing materials also contract and expand daily as they heat up during the day and cool down at night. A roof with a cool coating doesn’t experience such large daily temperature fluctuations, so it undergoes less thermal fatigue. Reflective roof coatings are usually sold as maintenance products because they extend the life of the roof.
This product is best for low slope or flat roofs which have low insulation levels and mineral cap sheet or single-ply roof membranes. Adding a cool coating is most beneficial for a building which:
♦ Is in a climate with hot, sunny weather during at least part of the year
♦ Uses significant cooling energy and/or has problems maintaining comfort
♦ Has a large roof area compared to the rest of the building’s surface area
♦ Has roofing which tends to crack and age prematurely from sun damage
Prior to 1998 there were few standards regarding effectiveness or quality of products. The industry formed the Cool Roof Rating Council (CRRC) in 1998 to provide information and develop a comparative rating system. Look for reflective information or Energy Star labeling on roofing products.
Performance & Costs
When a dark single-ply roof is coated with a white reflective coating, the albedo can rise from 0.20 to 0.65-0.85 and surface temperatures will remain below 135F in sunny weather. With a lightly insulated roof on a low-rise building in a cooling climate, heat reflective coatings can save over 40% of cooling energy used by the building and have a lifetime of 10 to 15 years. Roof lifetimes will be extended because of the reduced temperatures.
Numerous studies confirm that coatings can reduce surface temperatures by 50-80F and save significant amounts of cooling energy during summer months. Regardless of the amount of roof insulation, buildings tend to show reductions of 25-67% in cooling energy usage.
Typical coating costs can vary from 50 cents to $1 per square foot depending on quality of coating and roof condition. Reflective coatings will extend the life of an existing roof by lowering temperatures, but it cannot repair a failed roof. A high quality coating may last for over 10 years on a roof in good condition and extend the life of that roof.
Roof coatings are readily available through a large number of manufacturers, including Conklin. The primary barrier to use of this product is the fact that it is viewed by many installers as a maintenance product and not recognized for its energy performance.
If you are interested in white roof coatings for your building, to find a professional Conklin roofing contractor in your area, please click here.
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