Exterior Paint vs Temp Inside
September 9, 2020 2:44 PM   Subscribe

Will painting the exterior of our house with a darker color have a huge affect on the temperature inside the house?

We are getting ready to paint the exterior of our house. We're looking at using darker colors. For example a darker green or blueish grey. They're about LRV 20 on the LRV paint scale with 100 being the lightest and 0 being the darkest. My question is will these colors have a major effect on the temperature inside our house? We live in Southern California in a valley so temps can reach the 100's. I assume there may be some degree of heat increase but will it be extremely noticeable or not really? Any info here is appreciated!
posted by ljs30 to Home & Garden (8 answers total) 1 user marked this as a favorite
 
Anecdata: I recently repainted my pretty-well-insulated house from light grey to navy (LRV 4), and haven't noticed any difference. It hits 100F here sometimes and the south-facing wall was sun-bleached.

Even with less insulation, I'm guessing the heat transfer from the siding to the plywood/housewrap to the studs to the drywall is pretty inefficient and you wouldn't notice the difference from paint color. If you need caulking to happen as prep for painting, sealing everything up could even keep your house a bit cooler.
posted by momus_window at 2:58 PM on September 9


I went from very pale yellow to very dark blue and didn't notice a difference.
posted by HotToddy at 3:00 PM on September 9


Your insulation is going to matter here. Well-insulated walls won’t transfer as much heat to the interior as poorly insulated walls will. A lot of homes in Southern California are poorly insulated, though.
posted by mr_roboto at 3:21 PM on September 9


I don't think it'll have an effect on the inside temperature of the house but it will on the outside temperature around the house. My house is navy blue and in the afternoon when it is in the sun I can feel the difference in temperature as I walk up the driveway to the house.
posted by any portmanteau in a storm at 3:31 PM on September 9


I'm in California with decent insulation and no A/C and painted my house a moderately darker color a few years ago. My indoor thermometer now tops out about 4 degrees higher during heat waves than it used to. Take this with a grain of salt as it isn't a controlled experiment...
posted by aws17576 at 7:27 PM on September 9


Dark colours can stress the house 'skin' - I'm aware of several cases where dark colours have resulted in building skin failure - leaks and worse. I'm in NZ and we have a company Resene who makes paint called cool_colours that looks dark (i.e. low LRV number) but has a high heat reflectivity.
posted by unearthed at 7:40 PM on September 9


Your insulation is going to matter here.

This^^^^^

The colour of the house will not matter otherwise.

If it is hot inside, add double or triple-celled blinds to the windows where the sun comes in.
posted by Hey, Zeus! at 9:46 AM on September 10


If you have a heat pump based air conditioner or ever plan to get one, a dark house will make it work harder and your electricity bills will go up. Window insert air conditioners will also be less efficient.
posted by jamjam at 1:29 PM on September 11


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