Question

Is there an eco-friendly exterior paint that insulates?

Asked by Tracy
Scottsdale, AZ

I live in AZ and I am told that the manufacturer of an eco-friendly paint is here in AZ and that this paint has an insulating effect. It is a two-part paint. I cannot seem to find it or the name of the manufacturer. Does anybody know what I am talking about?

Answer

Florian Speier

Answered by Florian Speier

Louisville, CO

Zeitgeist Design LLC - Swiss Architect

May 7, 2011

Tracy,

I cannot find the Arizona company that you mention. The only eco-friendly manufacturer of insulating paints known to me is Ecos. Their insulating paint can be found here.

A negligible insulating effect

I was about to write you a long article on why the insulating effect of “insulating paint” is rather miniscule or even nonexistent.

  • Then I saw that Scientific American has already done this work for me. (Note that this article contains links to several other manufacturers of insulating paint, should you want to purchase it.) 
  • The Scientific American article provides a very succinct and accurate description of the limitations of insulating paint.
  • You may also want to take a look at this article on TreeHugger.

Although some members of the green building community stand behind such products, the overwhelming consensus is that insulating paint is just too good to be true.

  • The EPA does not recommend paints and coatings be used in place of traditional bulk insulation, and notes that it has not seen any independent studies that can verify the insulating qualities of these paints.
  • In short, it is close to impossible to insulate at all within the thickness of a paint layer.
  • The best common insulations for buildings, such as closed-cell spray foam, get an R-value of about 7 per inch. Now, if you would apply the paint very thickly, say about 1/32 of an inch, and if it would insulate as well as spray foam, you would get an R-value of less than 0.25, which is a negligible amount.

Manufacturers can't explain

Unfortunately, the manufacturers of insulating paint, like Ecos, cannot make this calculation work, either. Ecos’s product description claims that R-values and its testing are “not really appropriate to thin paint layers” but unfortunately cannot offer a satisfactory explanation for how their paint actually insulates.

The last resort of manufacturers is to tell you to feel the temperature difference between a painted and an unpainted surface.

  • That may be true, but does not necessarily translate into energy savings for your house.
  • The surface temperature of a material is not the only variable that determines the total heat flow between objects. 

Tagged In: low voc paint

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