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Name: Kathleen J.
Status: other
Age: 40s
Location: N/A 
Country: N/A
Date: 9/15/2004


Question:
I am building a house and want to make it energy efficient. I live in southern Alabama and have tried to find out about what roof colors will absorb the least amount of heat. I know that white is best, but white doesn't go with our color brick. Also, the builders in this region of the country are not at all concerned with ecology. They have been of no help. I have searched the Internet as well and have not found an answer to my question.

What color would best a brown roof (weatherwood) or medium grey (shadow grey)?


Replies:
Kathleen -

I applaud the upbringing of your children.

Not knowing the exact colors you are dealing with, I cannot give you a decisive answer, but I would suggest that your kids might find it interesting to do the investigation for you in pursuit of your goal. Can you acquire a tab of each shingle color? If so, place each of them in the sun with a thermometer set behind them and record the change in temperature over a period of time. (It would be good to insulate under your experiment by placing them on something like bath towel.) Graphing the data wound answer your question, and give your kids the idea that they are responsible for your family's earth-friendly efforts.

Larry Krengel


Kathleen,

I am not sure that either of your choices will have a practical difference over the other. I would pick the color you like best.

Bob Hartwell


Kathleen,

Thanks for your question and for teaching your children to be responsible citizens.

The Department of Energy's Office of Energy Efficiency and Renewable Energy (EERE) has a web site that discusses several options for constructing houses that are energy efficient -- including roofing recommendations. Here is the web site:

http://www.eere.energy.gov/EE/buildings.html

I hope this is useful.

Todd Clark, Office of Science
U.S. Department of Energy


When the color is constrained by other considerations as in your case, probably the best thing to do is make sure that there is good thermal insulation underneath the roof. This means reflective bats of fiber glass. So even if the roof exterior gets very hot it cannot transfer that heat into the house. An automatic temperature controlled exhaust fan from the attic space to the outside also is very helpful in circulating hot air out of the attic space and pulling in relatively cool air from the outside through the attic vents.

Vince Calder


There are suppliers that ARE concerned about the reflectivity of various roof surfaces. I did a web search of "reflectivity of colors" and found several companies that would be happy to sell you roof coatings that reflect most of the heat and thereby help to keep your house cool. Their "EverCool White" reflects about 80% and their "EverCool Tan" reflects 70% (they say). By the time you get to "Brown Tile" only about 5% is reflected (so 95% is absorbed to heat you house.)

I suggest you search the web for someone in your neighborhood who is a provider of high reflectivity roofs. I know nothing of these companies and, for obvious reasons, cannot make any specific recommendations. It is obvious, however, that a white roof reflects the most heat and so will keep your house the coolest. Darker colors absorb more of the heat (black absorbs all).

It is also obvious that there are companies willing to help you with this project. Be aware, of course, that they are also willing to make a profit!

Best, Dick Plano...


I assume that you want a color that keeps the roof cool because Alabama tends to be hot. I regret that I do not know which color would do that. You would need to find out from the manufacturer what the optical absorption is. Black would close to 100% and would be bad. White would be close to zero percent and would be good. If one is clever, one can use the light meter in a camera to get a rough estimate.

Bob Erck



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