"SAN FRANCISCO -- Returning to their ranch-style house in Sacramento after a long summer workday, Jon and Kim Waldrep were routinely met by a wall of heat.
'We'd come home in the summer, and the house would be 115 degrees, stifling,' said Mr. Waldrep, a regional manager for a national company.
He or his wife would race to the thermostat and turn on the air-conditioning as their four small children, just picked up from day care, awaited relief.
All that changed last month. 'Now we come home on days when it's over 100 degrees outside, and the house is at 80 degrees,' Mr. Waldrep said.
Their solution was a new roof: a shiny plasticized white covering that experts say is not only an energy saver but also a way to help cool the planet."