Cool construction materials offer energy saving and help reduce smog. ASTM standardization news 23

Modern urban areas usually have darker surfaces than their surroundings. Use of dark roofs and pavements affects the climate, energy use, and habitability of cities. At the building scale, dark roofs are heated by the summer sun and thus raise the summertime cooling demand. Figure 1 shows the midday temperatures of various horizontal surfaces exposed to sunlight. For highly absorptive (low-albedo*) surfaces, the difference between the surface and ambient air temperatures may be as high as 50°C (100°F), while for less absorptive (high albedo) surfaces such as white paint, the difference is only about 10°C. For this reason, "cool construction materials " (which absorb little insolation) are effective in reducing cooling energy use. Cool surfaces incur no additional cost if color changes are incorporated into routine re-roofing and resurfacing schedules. Scientists at the Lawrence Berkeley National Laboratory and the Florida Solar Energy Center have measured cooling energy savings in the range of 10 to 50 % (ranging from $10 to $100 per year per 100ft2 (approx. 100m2) in several residential and small commercial buildings. Numerous experiments on individual buildings in California and Florida show that painting roofs white reduces air conditioning load between 10 and 50%, depending on th