Development of an Accelerated Microbial Procedure (Final Report)

Cool-roof coating technologies make buildings more energy efficient, reducing energy consumption as well as air pollution in temperate and hot climates. The performance of a cool roof can diminish significantly when exposed to adverse environmental agents such as dust, soot, and pollens as well as microorganisms. There is currently no equivalent method to accelerate testing of cool roof erformance. We developed an experimental procedure to test cool roof samples using a defined mixture of both photoautotrophic and heterotrophic microorganisms that would produce an equivalent, faster test for biodeterioration. The mixture consists of 6 bacterial, 3 algal, and 4 fungal species suspended in rich media. Microbial biofilms developed rapidly on the coating surface. Any cool-roof technology could be tested using this microbial aging procedure. If the surface of a material is accessible to the microbial mixture, the growth of a microbial biofilm could reduce the solar reflectance to less than 50% of its initial value within 2 months. Thus, it completes the test cycle required by the ENERGY STAR^® program in only 2 months instead of 3 years by the biofilm alone.