Potential benefits of cool roofs on commercial buildings: conserving energy, saving money, and reducing emission of greenhouse gases and air pollutants

• DOI: 10.1007/s12053-008-9038-2
• Publication Date: 2009-04-02T13:32:34Z
• Authors: Ronnen Levinson; Hashem Akbari
• Keywords: Cooling load

Cool roofs—roofs that stay cool in the sun by minimizing solar absorption and maximizing thermal emission—lessen flow of heat from roof into building, reducing need for space cooling energy conditioned buildings. roofs may also increase heating cold climates. For a commercial decrease annual load is typically much greater than load. This study combines building simulations, local prices, electricity emission factors, estimates density to characterize local, state average, national average savings, penalties, cost reductions per unit area. The uses four prototypes—new office (1980+), old (pre-1980), new retail (pre-1980)—were simulated 236 US cities. Substituting weathered white (solar reflectance 0.55) conventional gray 0.20) yielded annually saving area ranging 3.30 kWh/m2 Alaska 7.69 Arizona (5.02 nationwide); penalty 0.003 therm/m2 Hawaii 0.14 Wyoming (0.065 an 0.126/m2 West Virginia 1.14/m2 ( 0.356/m2 nationwide). It offered CO2 reduction 1.07 kg/m2 4.97 (3.02 NOx 1.70 g/m2 New York 11.7 (4.81 SO2 1.79 California 26.1 Alabama (12.4 Hg 1.08 μg/m2 105 (61.2 Retrofitting 80% 2.58 billion square meters USA would yield 10.4 TWh; 133 million therms; 735 million. offer 6.23 Mt, offsetting emissions 1.20 typical cars or 25.4 peak power plants; 9.93 kt, 0.57 65.7 25.6 815 126 kg.