Best paint that reflects solar radiation?
I have a white stucco house that is poorly insulated and when it receives sunlight in the evening, the walls get quite warm as measured with an infrared thermometer. It has R-7 insulation in the 2X4 walls so there is something but not a whole lot. Anyway, I wanted to know if there is a good paint that can reflect solar energy.
3m Claims to have an additive that you can add to paint that will make paint more reflective of solar energy. Problem is, I can’t find any products that use this technology in their paint. On the cool roof we
Using the Cool roofs directory, I can find materials for roofs with high solar reflectance but not for wall paint.
http://coolroofs.org/directory
If there was some sort of directory for house paint, that would be useful.
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Replies
Dave,
The main reason that energy-efficiency experts don't rate the performance or emissivity of exterior wall paint is that the effect of wall paint on energy bills is minor.
1. What you need is wall insulation.
2. A new coat of white paint will help keep your wall cool on sunny afternoons, but the effect is small compared to insulation.
3. One year after you apply a new coat of white paint, the effect will be less than when the paint is newly applied. With every passing year, the reflectivity decreases.
4. There is a history of exaggerations from paint companies that taints this whole concept.
In short, get a good quality of white paint and paint your wall if you want. But don't expect miracles. The best approach is to start saving money for improved insulation -- perhaps EIFS.
Obviously insulation is a better option but I figured for a few hundred dollars, it's better to just change the paint. You believe in the cool roof products which even have an aged performance factor so why not paint? Paint doesn't benefit in winter and actually would hurt but since I don't have air conditioning in this room, I really need to do what I can to reduce the heat load without ripping out the stucco.
Dave R,
I'm not a paint expert, but I imagine you could use a roof coating on your wall if you wanted. That said, I doubt if it will perform differently from ordinary white paint -- which is to say, I don't think there would be enough of a difference between white paint and a fancy roof coating to result in a noticeable change in your comfort level or utility bills.