by leokino (Cádiz, Spain) January 11th 2010

since: 01/11/2010, Brain-fu: 10385

Good idea but a little old. In south Spain and north Morocco, among other places, we paint our houses in white since centuries for the same reason.

by Soofi_Camussi (Rosario, Argentina) January 12th 2010

since: 01/12/2010, Brain-fu: 269

my roof is red that's good or bad for global warming? :/

by tinny (Jaipur, India) January 12th 2010

since: 09/10/2009, Brain-fu: 457

@Soofi_Camussi: red also absorbs light and so all dark colours too. only light colours such as white, light green, etc reflects light. So, to reduce absorption next time paint it white

by leokino (Cádiz, Spain) January 12th 2010

since: 01/11/2010, Brain-fu: 10385

That's all right. In hot countries white colour and small windows. Keep windows open during fresh hours, close them complety in the hot time of the day and keep the interior of the house in darkness as much possible.
If you can do so, you'll need no AC

by PhilipH (Cambridge, United Kingdom) January 13th 2010

since: 01/03/2010, Brain-fu: 405

The term for this kind of activity is 'albedo modification'. This paper:
http://www.atmos-chem-phys-discuss.net/9/2559/2009/acpd-9-2559-2009.pdf
gives a global figure of 0.01-0.19 W/m2 of negative forcing (cooling), depending on what percentage of roofs we treat. This is small compared to the 3.7 W/m2 of positive forcing (heating) contributed by a doubling in atmospheric CO2 concentration, but as you point out it's cheap and easy so not without value.
An additional bonus however comes from the fact that less sunlight absorbed means a cooler house (or other building), reducing the amount of active air conditioning required in hot climates and hence reducing the amount of CO2 emitted.