A column in the Ashland Daily Tidings on Jan. 24 suggested that painting roofs white saves heating and cooling costs in southern climes. Unfortunately, it contained no information extrapolating from the southern examples to our climate conditions. How much benefit would such an effort produce here in the Rogue Valley?
— Becky S., Ashland
Locally, there isn't much in the way of research on what kind of cooling savings can result from making your roof white, Becky. Still, local sustainable building pros say taking such a step could result in cost savings in the Rogue Valley.
"It's really summer heating that white roofs will benefit," said Fred Gant, a green-building consultant who owns Southern Oregon Green Rating Services.
According to the National Weather Service, Medford's average high temperatures during June, July and August are 81 degrees, 90 degrees and 90 degrees, respectively. These averages beat out Roseburg, Klamath Falls, North Bend, Portland and Eugene. (Correction: The temperatures listed have been updated to accurately reflect the average high temperatures for the summer months.)
The reason white roofs can help keep buildings cooler is that they reflect sunlight that would otherwise allow heat to build up. As you may recall from the story you mentioned, Becky, dark-colored roofs absorb much more heat from the sun's rays.
Dark roofs can heat up 90 additional degrees, whereas white roofs heat up anywhere from 10 to 25 degrees. So having a white roof could translate to a 15 percent or so savings on cooling costs.