Paint It White - Can Paint Save You 10%, or even 20% on Cooling Bills?

Light Colored Roofs

There has been a growing buzz for the last couple of years about a new way to cool houses in hot climates.  The buzz has reached a louder tone lately since Steven Chu, the US Energy Secretary, brought the topic of money saving paint to the forefront.

So what is this magic paint that saves money?  It is light colored roof paint.  Yes, paint your roof and you may see noticeable savings of energy in your home (though reports of 20% are almost certainly overblown).

Now, this sounds crazy, and as of yet not many people have taken the leap.  So lets take a closer look and see what roof painting is all about.

The Theory of Painting Your Roof White

The basic idea behind painting your roof white (or a light color) is that light colors reflect more heat, whereas dark colors absorb heat.  Case in point, I was on my roof last November on a nice 75 degree day, but that roof surface was almost too hot to touch.


That heat absorbed by the roof can then radiant into your attic, and ultimately your home, creating a direct affect on your homes comfort and cooling bills.

Steven Chu also points to an indirect affect on climate.  The urban 'heat island' effect has long been known to exist because of the colors and materials used in cities.  An extreme example is Phoenix Arizona, which on the hottest summer nights may not cool below 90 degrees, but the surrounding suburbs and desert may be 10 degrees (or more) cooler.

Steven Chu claims that this effect, which causes everyone's cooling systems to work harder all night, could be noticeably reduced.  Just look to cities and towns in Greece and Israel, where white and off white creates a cooler (and picturesque) cityscape.

Further, on a global scale, more solar energy we be reflected back into the atmosphere, reducing one undisputed affect humans have on climate. According to the Nobel Prize winning Chu, a global scale of painting roofs white would have the same effect on climate as taking every car on earth off the road for 11 years.

How To Paint Your Roof White

Perhaps you are convinced, are looking for a project, or simply want to do everything you can to reduce your environmental impact. Or maybe you are skeptical but figure 'its worth a try'. Before you run down to your paint store and pick up 5 gallons of outdoor white paint, there are a few things you need to know.

There are a vast number of coatings, seals, and paints available for a roof. You must know what material your roof is (asphalt shingle, tile shingle, etc), and preferably the age and general condition. Some roof types need to breath, and others would need specific types of sealers or paints.

There are seals, coatings, and paints available, each with varying pros and cons. Paints will accomplish the reflecting goal, but not much else. Some seals and coatings will actually increase the longevity of the roof as well - again, depending on what your roof is made of.

All require reapplication after some period of years.

But Is Painting A Roof Really Worth It?

At this point I think it is generally unknown if you will achieve payback on a roof painting project. Expect to pay $400 to $800 on the coating/paint alone. But if somehow the claims of 20% cooling savings are true, you would achieve payback and even some return on your investment over time.  I just have a hard time believing that much savings is possible - perhaps only on flat roofs would you approach 20%.

And I know that painting my roof white would not go over very well with my neighbors, HOA, or wife.

Radiant Barrier and House Paint - More Practical?

As an alternative, you may want to consider a radiant barrier in your attic instead.  The radiant barrier also helps reduce heat transfer from the roof. The benefit of the radiant barrier is that it is entirely inside the attic, so you won't have to worry about aesthetics and maintenance.

Further, if you live in a hot climate, it is also worth considering painting your house exterior (i.e. your walls, not the roof) a shade or two lighter next time you re-paint. This simple step could save a few dollars each year, and you'd be performing a task (repainting) that would have to be done anyway.

Have You Painted Your Roof?

If you've painted your roof or know someone who has, please leave a comment or send your acquaintance to this post so they can leave a comment.  It would be great to get some real-world feedback on how it has worked out, and the pros and cons.