Measured energy savings from the application of reflective roofs in two small non-residential buildings

Energy use and environmental parameters were monitored in two small (14.9 m²) non-residential buildings during the summer of 2000. The buildings were initially monitored for about 1 1/2 months to establish a base condition. The roofs of the buildings were then painted with a white coating and the monitoring was continued. The original solar reflectivities of the roofs were about 26%; after the application of roof coatings the reflectivities increased to about 72%. The monitored electricity savings were about 0.5 kWh per day (33 Wh/m² per day). The estimated annual savings are about 125 kWh per year (8.4 kWh/m²); at a cost of $0.1/kWh, savings are about $0.86/m² per year. Obviously, it costs significantly more than this amount to coat the roofs with reflective coating, particularly because of the remote locations of these buildings. However, since the pre-fabricated roofs are already painted green at the factory, painting them a white (reflective) color would bring no additional cost. Hence, a reflective roof saves energy at no incremental cost.