Submitted by Louisa May
Many house paints are labeled low-e for low emissivity. Emissivity refers to how much heat is emitted from a surface.
Some of these paints, the ceramic ones, contain small, hollow ceramic beads.
The idea is that when the paint dries, the beads bond together and create a radiant barrier. This radiant barrier translates into energy savings for the consumer.
Or does it?
Back in the 1990’s, the ORNL (Oak Ridge National Laboratory) Energy Division conducted a series of tests on radiant barriers, including a test of twenty- four different roof coatings available on the market.
Their findings, in part:
One of the big problems with the energy efficiency of the products was the accumulation of dust. Over time, dust wears away the radiant barrier’s effectiveness, reducing the potential of energy savings. An attic floor is not a good place to use ceramic paint.
Roofs vs. walls
Cutting cooling costs is a possibility. The coating ideally deflects heat before it is absorbed by the surface. So, a roof deflects the heat first, and therefore the coatings are more efficient on roofs than on vertical walls.
Tests suggested that after just one year of weathering, roof coatings became 15 to 25% less effective.
Ceramic paint goes on thicker than a standard non-ceramic paint and tends to hide cracks and imperfections in the wall, and the paint lasts longer. Most of these paints have low VOC’s. too.
But a study done by the University of Cincinnati on airborne ceramic fibers concluded with a warning that consumers be careful when using anything containing this material. So, even if you’re using a ceramic paint with low VOC’s, wearing a mask while painting is probably a good idea.
Another thing to keep in mind is that many advertisements for these products read like independent test results. The US Department of Energy offers a radiant barrier fact sheet, but ceramic paint products used on television shows are more likely to be paid endorsements.
Opinions differ on the energy savings you’ll get with ceramic paint. Before making a purchase, the smart buyer should beware the magic bullet.
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