White roof or "green?" The answer to that question is sometimes white, sometimes green (and almost never the third option, black tar) depending on geography, according to a new study by Arizona State University and the Environmental Protection Agency (EPA), USA Today reported.

White and green rooftops, or those covered with plants, lower the surface temperature during the summer months, cheapening air conditioning bills and creating significant environmental impacts.

"Each can completely offset the warming due to urban expansion and can even offset the warming due to greenhouse gas emissions," lead author Matei Georgescu, a sustainability scientist at Arizona State University, told USA Today.

For urban developers in parts of the country with dramatic differences between seasons, like the northeast and Midwestern locations like Chicago, Detroit, and Minneapolis, green roofs would seem to have more benefits (but results aren't yet conclusive, according to the study's authors). Though white roofs reflect the sun and lower surface temperatures more effectively in the summer, green roofs trap more heat in the winter months, reducing heating costs more effectively than white roofs, which absorb less heat.

In hotter or more temperate regions like Arizona, California, and the south, a white roof can represent as much as a 50 degree temperature drop compared to black tar roofs on hot enough days (of which there are many in those places) without experiencing a drop off in warmer winter months, according to the study.

White roofs, however, come with other tradeoffs besides high heating bills. They reduce precipitation in wet areas like Florida (a negative impact), but have less of an impact in more arid regions like California.

"What we emphasize is that there are no one-size-fits-all solutions," Georgescu told Popular Mechanic.

From a purely economic sense, there is, according to Author Rosenfeld from a separate, 50-year study out of Berkeley Labs.

"White roofs win based on the purely economic factors we included, and black roofs should be phased out," study co-author Arthur Rosenfeld said in summarizing his financial-based research. Green roofs do "a good job at cooling the building and cooling the air in the city, but white roofs are three times more effective at countering climate change than green roofs."