Of course one could use a vent but this is not feasible for me. Is there a low-tech solution, like some kind of a specific curtain? I could also cover my window with an opaque board, letting some space but this lowers dramatically the quality of the air (mainly CO2 wise).

  • I guess something like standard tiling window blinds let in too much light? Dark colored blinds would let in less light than the typical white blinds. – JPhi1618 Oct 11 at 14:26
  • Do you have the legal right to modify the building? – Harper - Reinstate Monica Oct 11 at 18:22

3 layers of pegboard (pierced hardboard), internal surfaces painted black, with the middle layer offset, and spacers between the layers. This should provide little or no straight path for light, but allow ventilation.

  • Paint the peg board black to avoid light reflection. Also, a small computer fan or two mounted on the inner board to draw air through the smaller holes that may not "breath naturally" all that well. – Alaska Man Oct 11 at 19:57

Consider a combination of options:

  1. Awning over the window. This keeps sunlight from striking the window at least at mid day. The wider the awning is, the more time it shades the window.

  2. Exterior bamboo rollup blind. This will block about 90% of the light. If you mount it so that it stands a few inches out from the wall, it won't impede the air much at all.

  3. Miniblinds. The cellular ones block too much air flow. Get the blinds is as dark a colour as you can. (Dark blue?) In use angle the blinds so that light must reflect upward to get in. This still allows good airflow, but no direct light at all.

  4. Double drapes. You can get nested curtain rods, with the inner set being about 2" from the wall, and the outer set about 4". Traditionally they are used with sheers on the inner layer to let in light and air, but still give privacy, and a heavier drape used at night in winter and made for reducing drafts. (Good windows are a recent invention) But there is no reason you couldn't use some breathable fabric that was dark.

  5. Screen. A folding screen that stands a foot from the window with the back side painted flat black, or if you can afford it, vanta black.

Light reduction is multiplicative. But the human eye is sensitive to a huge variation in light. Normal office lighting is about 1/10,000 that of sunlight.

Have you considered a sleeping mask?

  • Vanta black is new for me. Thanks for this! And a mask (although uncomfortable) is a perfect solution. – OMGsh Oct 11 at 16:09
  • 1
    Vanta Black isn't commercially available yet. (And probably never will; that stuff is annoying to work with.) – user3757614 Oct 11 at 17:31

A black painted louvre, if you still get too much light, add another behind it with the slats slanted the other way.


Of course you could just roll down the shutters letting just the air gaps open, just like this. Won't be vanta-black but it's really effective.

  • Not enough air flow. I didn't measure how CO2 levels drop but can feel it. – OMGsh Oct 25 at 15:05

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