It's not quite what you think. But the California Air Resources Board (CARB) has just passed the first legislation requiring solar-efficient glass to be used in all new cars sold in that state starting in 2012. Beyond literally keeping occupants cooler in the summer, the coincident reduction in the use of air conditioning will help improve average fuel economy and decrease the amount of greenhouse gas emissions. This new regulation will be enacted using a two-stage roll. From 2012-2015, all vehicle glass must be capable of rejecting at least 45 percent of the sun's total heat-producing energy, except for the windshield which will have a 50 percent rejection requirement. Starting in 2016, the numbers will rise to 60 percent all around.
CARB data indicates that compared to today's average vehicles, the new standard will cut relative interior temperatures by approximately 14 degrees Fahrenheit in cars and 12 degrees in pickups and SUVs. Many manufacturers are already using some form of heat-rejecting glass in at least some of the greenhouse panels. These can be created using either chemical additives that absorb and trap the energy or a laminated coating that contains microscopic metal flecks that reflect/reject the heat without impairing their overall transparency.
Complying with the new requirements is expected to cost about $70 per vehicle to meet the 2012 standard and about $250 to reach the 2016 level. With annual gas savings projected at $16 and $20, respectively, payback periods would run five to 12 years. CARB also says manufacturers will be allowed to offer alternative solutions that would achieve an equivalent result. "This is a common-sense and cost-effective measure that will help cool the cars we drive and fight global warming," said California's ARB Chairman Mary D. Nichols of the decision. "It represents the kind of innovative thinking we need to reduce greenhouse gas emissions from our vehicles and steer our economy toward a low-carbon future." It will be interesting to see how many states that have adopted California's more stringent emissions regulations will also see fit to mandate its latest strain of CO2-reducing green technology.