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Community and Q&A

Exterior vs Interior blinds

this_page_left_blank | Posted in Mechanicals on

I know exterior has superior performance, but can anyone quantify how much? The latest heat wave has me lamenting the fact I didn’t go with motorized, exterior blinds for the four east/west windows. Original plan was interior blinds. It’s not too late to change plans, though the timeline is getting pretty tight.

Can anyone recommend a place to get these at a reasonable price? I priced them out locally last year, and they were a lot (I think four of them came close to the cost of a ductless minisplit).

How crazy would it be to have interior blinds, plus a temporary air-tight cover to put over the blind? The interior jamb/sill is about 10″ deep. I could open the exterior window slightly to prevent heat building up in that space. I’m thinking something like a magnet seal that you find on steel doors.

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  1. GBA Editor
    Martin Holladay | | #1

    Simple awning-style shutters are probably cheaper than motorized exterior blinds.


  2. this_page_left_blank | | #2

    I meant to mention, we have casement windows. Aside from that, with those style of shutters you're not ever going to see much out of the window.

  3. GBA Editor
    Martin Holladay | | #3

    I don't know the size of your windows, or how hot your climate is.

    The discussion that follows probably won't help you, because I imagine that your windows are already installed. But in many hot climates, the majority of east-facing windows and west-facing windows are blocked by interior shades or curtains almost all day long -- indicating (to me, at least) a design error.

    If windows are causing so much discomfort that they need to be protected by blinds, it's worth imagining whether the house would perform better with much smaller windows.

  4. this_page_left_blank | | #4

    The windows are pretty modestly sized, and our climate is not overly hot (near London, Ontario - don't know what climate zone that's equivalent to, the one people always refer to here does not extend outside the US). However, we have occasional heat waves, where it's hot during the daytime and doesn't drop below room temperature overnight either.

    We have three east facing windows, two of which are 32x45 (rough opening), one is 32x55. The west side has one 32x55.

    The more I think about the interior covers, the more sense it makes to me. Quick to put on and take off, don't have to go outside, minimal effect on outward appearance, about twenty to a hundred times cheaper than motorized shades.

  5. Expert Member
    Michael Maines | | #5

    Trevor, in Passive House design it's common to have exterior blinds or shutters of some sort, sometimes sliding, because once the solar energy gets through the glass it's in your house. But in a relatively cool climate, and if you're not going for super high performance, I think your approach will work.

  6. calum_wilde | | #6

    I have nothing but anecdotal information on this, but I've found that keeping the curtains closed and the windows cracked a little is the most effective use of indoor window coverings. It seems to allow the heated air to to move outside instead of moving into the house. It's by no means as effective as exterior coverings would be, but it seems to me to be better than closed curtains and closed windows.

    Now if you're running AC I certainly wouldn't open the windows.

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