An office building used as a federal test bed for energy-efficient roofs

The energy savings benefits of re-covering the roof of an existing federal office building with a sprayed polyurethane foam system are documented. The building is a 12,880 ft{sup 2} (1,197 m{sup 2}), 1 story, masonry structure located at the Oak Ridge National Laboratory (ORNL), Oak Ridge, TN. Prior to re-covering, the roof had a thin fiberglass insulation layer, which had become partially soaked because of water leakage through the failed built-up roof membrane. The average R-value for this roof measured at 2 hr{center_dot}ft{sup 2}{center_dot}{degrees}F/Btu (0.3 m{sup 2} {center_dot}K/W). After re-covering the roof, it measured at 13 hr{center_dot}ft{sup 2}{degrees}F/Btu (2.3 m{sup 2}{center_dot}K/W). The building itself is being used as a test bed to document the benefits of a number of energy efficiency improvements. As such, it was instrumented to measure the half-hourly energy consumption of the whole building and of the individual rooftop air conditioners, the roof heat fluxes and the interior air and roof temperatures. These data were used to evaluate the energy effectiveness of the roof re-covering action. The energy savings analysis was done using the DOE-2.lE building simulation program, which was calibrated to match the measured data. The roof re-covering led to around 10% cooling energy savings and around 50% heating energy savings. The resulting energy cost reductions alone are not sufficient to justify re-covered roofs for buildings having high internal loads, such as the building investigated here. However the energy savings do contribute significantly to the measure`s Savings-to-Investment Ratio (SIR)