Elementary School Replaces Roof With Something More Energy-Efficient

Jefferson Houston Elementary School, built in 1970, is a single-story, 83,000 ft2 building in Alexandria, Virginia. Local temperatures often rise to a humid 100oF during the summer and drop to 10oF in the winter. Until 1994, these heating and cooling demands were managed by electric air-conditioning and electric-resistance heating systems. Larry Gilbertson, Director of Facilities, had analyzed the school’s historical energy expenses and determined that the school should have an overall energy efficiency upgrade as soon as it could be funded. By 1994, the existing EPDM (ethylene propylene diene monomer) roof had reached the end of its useful life. Mr. Gilbertson knew that the roof needed to be replaced at a low first cost, but he also recognized the opportunity to lower the school's energy bills by specifying energy-efficient roofing materials. Working with Project Manager Mark Krause, Gilbertson compared several options—built-up, modified bitumen, EP (ethylene propylene), and metal—for replacing or repairing the roof, considering both first costs and annual maintenance costs.

Based on Krause's recommendation, Gilbertson specified a white, insulated, reflective, 60-mil EP roof manufactured by Stevens Roofing Systems. The reflectivity of the new roof, compared with the old roof, increased from less than 20 percent to 78 percent, and the insulation value increased from R-10 to R-20. Because the existing roof had significant water ponding, Gilbertson also elected to have roof drains installed. These drains not only prolong the life of the roof, but also help maintain its reflectivity by enabling dirt to be flushed from the roof when it rains. The cost of installing the EP material was no higher than the cost of the alternate materials considered. Furthermore, because the material is heat-welded, it could be applied without substantial odors-an important factor in protecting air quality in the classrooms. As a result of installing this energy-efficient, insulated roofing system, Jefferson Houston's energy costs fell to a post-upgrade average of $90,000 per year from a preupgrade average of $121,000—a reduction of $31,000 in annual energy costs.

These savings are due to both greatly reduced electric power demand and lower electric energy consumption. The school realized these savings despite a conversion of the interior courtyard space in 1994 into additional classrooms, which significantly increased the building's heating and cooling demands. The white EP membrane accounted for approximately 30 percent of the realized savings. Based on their energy-saving potential and ease of installation, white, reflective, single-ply membrane materials have become the roofing product of choice for Alexandria City Public Schools. Following the new roof's installation, Krause upgraded the lighting, replaced the air-conditioning and heating units, and installed an energy management system. The building's total energy bills decreased by 50 percent from $121,000 to $60,000 between 1994 and 1997, because of these comprehensive upgrades. On Alexandria City Public Schools’ partnership with ENERGY STAR Labeled Buildings SM, Gilbertson remarked: “I appreciate EPA’s efforts to continue providing unbiased technical information to us. We have a good source to go to for information not only about selecting roofing products, but also about financing projects, communicating our success to the community, and selecting other types of energy efficient building options.”