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We are picking exterior paint colors for our stucco house. The interior walls are plaster and there isn’t insulation in the walls.

I want to stay away from dark colors because I think it will make our house hotter(we live in Southern California where it is sunny most of the year).

Is my concern valid?

If I insulate my walls, will I be able to choose dark colors?

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  • As someone who works in the construction industry in SoCal, I'd like to say yes, but there's a ton of variables here. Age of house, location, wall material, stucco type, facing directions, tree coverages, etc. If you're in an isolated desert in Blythe, it's different than if you live in Mount Baldy.
    – Anoplexian
    Feb 11, 2019 at 20:19
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    Just remember that the sun only emit's about 50% of it's power in infrared, and only 40% in visible, so make sure your paint is also reflective in the non-visible bands ag.tennessee.edu/solar/Pages/What%20Is%20Solar%20Energy/…
    – Sam
    Feb 11, 2019 at 21:01
  • What color/material is your roof? You're not worried about the walls when you have a dark colored roof right?
    – JPhi1618
    Feb 11, 2019 at 21:13
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    @Sam please post an answer based on that. A blue paint that reflects infrared light is better than a white paint that doesn't. None of the current answers reflect that.
    – Kat
    Feb 11, 2019 at 21:36
  • Dark colors don't "hold" more heat. They transmit (absorb and emit) heat faster than lighter colors do. That means a dark-colored house will heat up faster in the day and cool off faster at night.
    – Monty Harder
    Feb 11, 2019 at 21:41

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A darker color absorbs more heat so yes it will heat the home more during the day. Your concern is valid. White is the least absorbent color and black is the most absorbent color.

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  • Many dark colors also fade more quickly in the sun as well.
    – JPhi1618
    Feb 11, 2019 at 21:14
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If you insulate your walls, you will thus be warmer during the summer and winter, and a black exterior would absorb sunlight and warm your house lightly. A white paint would reflect light and keep the outside of your house cooler.

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    I think you meant cooler in summer, but yeah.
    – isherwood
    Feb 11, 2019 at 19:09
  • I’ll definitely check it out.
    – milesmeow
    Feb 12, 2019 at 1:38
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Yes. Every paint has a reflectivity - the cosmological term for the same thing is albedo. This is a hard number, and the paint manufacturer can tell you what it is. It will be a percentage; for instance my favorite gloss white has a 91% reflectivity or albedo.

All the rest is absorbed. There is no magic where some of the absorbed energy is radiated, that would be part of the albedo!

Solarization is about 1000 watts per square meter square-on with the sun. Figure for the total exposure area, factored for the angle to the sun (which changes). Figure the hours of exposure. Multiply that by your paint's reflectivity and that will be your house's solar gain.

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If you really want a dark color you can add ceramic beads to the paint which will reflect infrared heat away. e.g.: insuladd I want to do this next time I paint (SoCal also) even if I use a light color paint.

Here's an article on BobVila.com with more information.

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It does not matter much. Yes, a dark color absorbs more heat, but it also radiates more away. It would become hotter faster during day but cool down much faster at night. A white surface absorbs less but radiates less. I would go for a white color because in direct sunlight the surface temperature of a black surface can become scalding hot, which is not fun if you accidentally lean on it or have kids around.

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  • This is pretty obviously wrong. The idea seems correct, but go touch a black surface on 100 degree day vs a white surface which is hotter?
    – Sam
    Feb 12, 2019 at 1:31
  • @Sam I suppose that most of the heat (absorbed from the outside trough radiation and on warm days through convection, and generated within) is convected away, not radiated away, so that the color is secondary for getting rid of excess heat. It is important for the fraction of the solar radiation the house absorbs though. The sun's radiation transports more energy than the house's because the sun is much hotter.
    – Peter - Reinstate Monica
    Feb 12, 2019 at 4:24

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