Global Cooling: Increasing World-Wide Urban Albedos to Offset CO2

Journal Article · Mon Jan 14 04:00:00 EST 2008 · Climatic Change

OSTI ID:962706

Akbari, Hashem; Menon, Surabi; Rosenfeld, Arthur

Modification of urban albedos reduces summertime urban temperatures, resulting in a better urban air quality and building air-conditioning savings. Furthermore, increasing urban albedos has the added benefit of reflecting some of the incoming global solar radiation and countering to some extent the effects of global warming. In many urban areas, pavements and roofs constitute over 60% of urban surfaces (roof 20-25%, pavements about 40%). Using reflective materials, both roof and the pavement albedos can be increased by about 0.25 and 0.10, respectively, resulting in a net albedo increase for urban areas of about 0.1. Many studies have demonstrated building cooling-energy savings in excess of 20% upon raising roof reflectivity from an existing 10-20% to about 60% (a U.S. potential savings in excess of $$1 billion (B) per year in net annual energy bills). On a global basis, our preliminary estimate is that increasing the world-wide albedos of urban roofs and paved surfaces will induce a negative radiative forcing on the earth equivalent to removing {approx} 22-40 Gt of CO{sub 2} from the atmosphere. Since, 55% of the emitted CO{sub 2} remains in the atmosphere, removal of 22-40 Gt of CO{sub 2} from the atmosphere is equivalent to reducing global CO{sub 2} emissions by 40-73 Gt. At {approx} $$25/tonne of CO{sub 2}, a 40-73 Gt CO{sub 2} emission reduction from changing the albedo of roofs and paved surfaces is worth about $1,000B to 1800B. These estimated savings are dependent on assumptions used in this study, but nevertheless demonstrate considerable benefits that may be obtained from cooler roofs and pavements.

• Research Organization: Ernest Orlando Lawrence Berkeley National Laboratory, Berkeley, CA (US)
• Sponsoring Organization: Environmental Energy Technologies Division
• DOE Contract Number: AC02-05CH11231
• OSTI ID: 962706
• Report Number(s): LBNL-2040E
• Journal Information: Climatic Change, Journal Name: Climatic Change; ISSN 0165-0009; ISSN CLCHDX
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
AIR CONDITIONING
AIR QUALITY
ALBEDO
GREENHOUSE EFFECT
HEAT EXCHANGERS
MODIFICATIONS
PAVEMENTS
REFLECTIVITY
REMOVAL
ROOFS
SOLAR RADIATION
URBAN AREAS