It's a brand new idea! 
From the New York Times, June 17, 1992:
Cooling (and Safety) Trend For Buses: White Tops
Published: June 17, 1992
Air conditioning school buses used to mean opening windows, which on a hot day simply let in hot air. Now more and more states and school districts are finding that painting the tops of school buses white makes the ride cooler.
The paint job may also make riding on school buses safer.
That conclusion was suggested by the response to a recent pilot program in North Carolina in which repainted buses were used. Motorists reported that white-topped, orange-bodied buses were easier to see.
As a result of the program, North Carolina will give school systems the option of specifying white tops when ordering new buses, said William Turner, an assistant superintendent for transportation at Brunswick County Schools. Buses with white tops cost a few hundred dollars more than regular buses, manufacturers say.
Part of the program involved studying the effect of the white tops on the temperature inside the buses. Digital thermometers were mounted on county school buses and readings were taken four times a day from August to December. The buses were tested while running and while parked.
Painting the bus tops white dropped the interior temperature an average of 10 degrees during the summer, with as much as a 17-degree difference at peak hours. Wintertime temperatures were lower by only 3 to 4 degrees.
The study also found that children behaved better on buses in cooler temperatures, Mr. Turner said.
And drivers preferred the two-toned buses. "It seems like the kids are a lot calmer," said Margaret Hughes, who has driven school buses for more than eight years.
Mr. Turner said his office had also received dozens of calls from motorists saying the white tops make the buses easier to see.
The Brunswick County program was modeled on similar programs in Florida and California, Mr. Turner said. Atlanta schools have been using the white tops for about four years, said Rick Rose, the president of the Georgia Association for Pupil Transportation. He said about half the buses in the state now have white tops.
The idea started in California, which has been using white-topped buses for about 20 years, Mr. Rose said.
Edited by Danno, 11 January 2013 - 01:14 PM.
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