Why are black roofs bad for your health and the planet? What are your best alternatives to help cool homes and the planet? Find out the physics behind cool colors from leading DOE physicists.
Tags: building science, cool roofs, roofs
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Dr Levinson talked about cool colored roofing tiles and I believe he said the reflectivity could reach as much as 60% (going by my short term memory) for a white colored tile. He also mentioned the neighbors would want to lynch you if you installed a white roof.
He is absolutely correct on the neighbors not liking a white roof. A white roof shows every little pine needle, leaf, blown around dust and bird dropping. Our coatimg is the brightest white and it does show the stuff.
Dr. Levinson spoke of the particles embedded on asphalt shingles and how they are tinting them with cool materials now of different colors. We always recommend a home owner tint our Cool Roof coating and add a few drops of blue, brown or green. It will not have the same exact reflectivity level of untunted white but it will lose very little.
We can tint our coating to any color as long as it is not a D-base color or darker. The darker you tint a coating, the lower the reflectivity as compared to untinted white.
When the sun bakes out the oils and resins in these roof shingles, the first thing that happens is the asphalt dries out and the ceramic particles lose their bonding and simply blow away in the wind. I cannot speak for the other coatings out there but ours penetrates past the granules and into the first layer of felt encapsulating the granules. NO MORE decomposition of the shingles.
One more reason to consider a Cool Roof coating rather than new shingles: why replace a roof that you can coat and turn it into a new roof with much higher reflectivity than the new shingles?
Another plus for coating an old roof: the coating will lock down the shingles against themselves. No more loss of shingles in high winds.
If a Cool Roof coating can also be used as exterior paint, wouldn’t it make sense? Are we not fighting radiant heat with the walls also? That should probably be a separate discussion.
Sorry for venting a little frustration at the end of that last reply.. I will strive to do better.
Next to a natural or man-made disaster, thermal shock is the biggest threst to the structural integrity of any building, residential, commercial or industrial..
Reduction in thermal shock is ALWAYS a part of our presentations for what we can do for homes, mobile homes, whatever type of building.
If whatever you do helps keep the building cooler in the hot months, look for the signs of thermal shock on the roof and walls and point them out to your customer.
Mr Rosenfeld mentioned they should look into the incentives of a white roof. I would like to mention, to that end, that white roof will also greatly reduce the amount of thermal shock.
I was a little surprised that there was no mention of heat absorption on walls and how much that contributes to heat gain in buildings and the heat island effect of a city.
I doubt if there is anyone reading this reply that has not walked down the sidewalk, on a hot summer day, an hour after the sun has gone down and felt the heat radiating out from the walls.. It is surely a significant amount because I myself have had to step off sidewalks and walk in the street because the walls of a building were radiating so much of that absorbed heat it was very uncomfortable to walk near it.
What do you do when you have an Energy Star Cool Roof coating, that they all seem to like and say works well on roofs but it also can be applied to exterior walls. Energy Star does not have a rating for exterior paints and it does not appear they want to hear about it.
They talked about white reflective roof coatings on cars, to reduce the AC load and save gas. I coated a small fleet of refrigerated truck trailers back in 1988. The fleet saved a reported 7 gallons a week per truck for their 4 and 5 day routes. Just a few years ago I contacted the Energy Star division that looks into energy savings in vehicles. I offered to coat the roof of a truck at my expense and I showed them what I did in 1988. What I got back was a very curt reply that said they "did not care" about the refrigeration units. They were only concerned with anything that could let the trucks get better mileage. 7 gallons a week,,, and how many refrigerated truck trailers are there in the US??? They dont care???? Good Grief!
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