Painting a roof white is better for the environment than driving a Prius or similar vehicle.

Judge as of 2010-09-29. The claim says painting a roof white gives a greater environmental (climate) benefit than driving a Prius or similar hybrid instead of a conventional car. True: credible studies (for example Akbari et al., or work from Lawrence Berkeley National Laboratory or the US Department of Energy) estimate the CO2-equivalent benefit of a white or cool roof, over a comparable period, as larger than the emissions saved by driving a hybrid rather than a conventional car. Mostly true: the comparison holds for typical roofs or climates but depends on assumptions (roof size, climate, years counted). Mixed: estimates conflict or the result depends heavily on assumptions. Mostly false: the claim rests on a real study but takes it out of context, for example by comparing a large commercial roof with one car, or the comparison holds only in narrow conditions. False: credible estimates show the hybrid's benefit clearly exceeds a white roof's under typical assumptions.

Set before the research began.

1. E1 [PDF] White Roofs Cool the World, Directly Offset CO2 and Delay Global ... LBNL Heat Island Group (Lawrence Berkeley National Laboratory) · 10 November 2008

   “Akbari et al. estimate that so retrofitting 100 m2 (1000 ft2) of roof offsets 10 tonnes of CO2 emission.”

2. E2 [PDF] White Roofs Cool the World, Directly Offset CO2 and Delay Global ... LBNL Heat Island Group (Lawrence Berkeley National Laboratory) · 10 November 2008

   “The average world car emits about 4 tonnes of CO2 each year.”

3. E3 Putting Rumors About Hybrids and Conventional Cars to Rest Audubon (National Audubon Society) · 11 August 2010

   “The Toyota Prius Plugin, for instance, gets up to 60 highway miles per gallon compared with the U.S. fleet average of 21.1 mpg, producing 60 percent fewer emissions over its lifetime.”

4. E4 White Roofs and Global Warming: A More Realistic Perspective Dr. Roy Spencer (drroyspencer.com) · 28 May 2009

   “Comparing this to our goal — offsetting 3.8 Watts per sq. meter for a doubling of CO2 — we find you have only offset 1.6% of the carbon dioxide emissions.”

The evidence says retrofitting 100 m2 of roof offsets 10 tonnes of CO2 (E1) without saying whether this is a one-time or recurring offset. No item gives the tonnes a standard Prius saves compared with a conventional car: E3 gives only a lifetime percentage for a Prius Plugin against the US fleet average, and E2 gives the annual emissions of an average world car. Without these, the evidence cannot settle the comparison.