August 2022 Energywise Tip: Cool Roofs

August 2022 EnergyWiseSM Tip: Cool Roofs
By: Energy Efficiency Program Manager Cory Fuehrer

According to the United States Small Business Administration, more than 99% (or more than 180,000) of all registered companies or commercial operations in Nebraska are classified as “small businesses.” Anyone living in rural Nebraska knows they are the lifeblood in their local communities. And, with only 10 of Nebraska's 529 incorporated cities, towns and villages exceeding populations of 25,000, our small communities are often gauged by the vitality of their downtown business district. Many of these small businesses occupy the historic buildings lining “Main Street” which have stood the test of time for decades, if not more-than a century.
When examining construction design of these buildings, a common roofing approach predominates: low-sloped and sealed, flat roofs with composite layers.
Some of these businesses with large air-conditioning loads have taken advantage of the energy savings a “cool roof” provides, but aerial photographs suggest many more have yet to discover this opportunity. A cool roof is light-colored and designed to reflect a majority of the sun’s radiant heat. In contrast, a conventional dark-colored roof absorbs a majority of this solar energy. Conventional roofs can reach temperatures of 150°F or more on a sunny summer afternoon. Under the same conditions, a reflective cool roof will stay more than 50°F cooler.
Recognizing the energy savings a cool roof can provide, the building-materials industry offers several products that increase roof reflectance, such as elastomeric coatings, single-ply membranes, tiles, or reflective metal roofing. Compared to conventional dark-colored roofs, these products keep 60 to 90% of the sun’s radiant energy from being absorbed into the business.
However, a cool roof does not necessarily provide savings for every low-slope roof. Some businesses and most Nebraska homes, regardless of their roof slope, may find their cooling energy savings are more than offset by additional heating costs in the winter. Unfortunately, cool roofs continue to reflect the sun’s rays, which reduce the building’s heating requirements in colder months.
While cool roofs achieve the greatest savings in hot climates when installed on air-conditioned buildings, some Main Street, Nebraska buildings with a high level of occupancy; large amounts of office equipment, manufacturing, food service operations or food retailing; or hospitality venues should investigate how cooling and heating costs compare throughout the year. If the building has high cooling costs, it may be a good candidate for a cool roof. When incorporated with a planned roof installation or improvement, cool roof options often add less than 10% to the total cost. That being said, all roofing projects can expensive. Thus, it is difficult to justify converting a standard dark-colored roof that is in good condition for the energy savings alone unless the building is also significantly under-insulated. For buildings with less than 2-inches of insulation or an R12 insulation value in the roof or above conditioned spaces, combined upgrades may yield a much quicker payback.
Your local utility and Nebraska Public Power District want to help you stay cool in the summer and warm in the winter while getting the greatest savings and value from the energy you need all year long. For more ideas on how you can make your home, business, or farming operation more EnergyWiseSM, contact your local utility or visit www.nppd.com.