some climates where there are more heating days than cooling days, white reflective roofs may not be effective in terms of energy efficiency or savings because the savings on cooling energy use can be outweighed by heating penalties during winter. According to the U.S. Energy Information Administration, 2003 Commercial Buildings Energy Consumption Survey, heating accounts for 36% of commercial buildings' annual energy consumption, while air conditioning only accounts for 8% in United States. Energy calculators generally show a yearly net savings for dark-colored roof systems in cool climates. A perfect roof would absorb no heat in the summer and lose no heat in the winter. To do this it would need a very high SRI to eliminate all radiative heat gains in summer and losses in winter. High SRI roofs act as a radiant barrier, providing a thermos-bottle effect. High emissivity cool roofs carry a climate penalty due to winter radiative heat losses, which reflective bare metal roofs, such as stainless steel, do not. Applications Cool roofs In a 2001 federal study, the Lawrence Berkeley National Laboratory (LBNL) measured and calculated the reduction in peak energy demand associated with a cool roof's surface reflectance. LBNL found that, compared to the original black rubber roofing membrane on the Texas retail building studied, a retrofitted vinyl membrane delivered an average decrease of in surface temperature, an 11% decrease in aggregate air conditioning energy consumption, and a corresponding 14% drop in peak hour demand. The average daily summertime temperature of the black roof surface was , but once retrofitted with a white reflective surface, it measured . Without considering any tax benefits or other utility charges, annual energy expenditures were reduced by $7,200 or $0.07/square foot.(This figure is for energy charges as well as peak demand charges). Instruments measured weather conditions on the roof, temperatures inside the building and throughout the roof layers, and air conditioning and total building power consumption. Measurements were taken with the original black rubber roofing membrane and then after replacement with a white vinyl roof with the same insulation and HVAC systems in place. Though a full year of actual data was collected, due to aberrations in the data, one month of data was excluded along with several other days which didn't meet the parameters of the study. Only 36 continuous pre-retrofit days were used and only 28 non-continuous operating days were used for the post-retrofit period. Another