I would like to ventilate my bedroom because air quality monitors show CO2 levels rising above 2000ppm every night.

I have two windows in the room, both with blackout blinds, but I prefer not to open them at night because they are street-facing and sun-facing and bring in noise and light. I also can't open the bedroom door for roughly the same reasons: light and sound from the rest of the house.

My question is, how can I ventilate the room given these constraints?

Two solutions I have thought of so far:

  1. Use window fans. This would work, except it would also probably bring in both light and noise.
  2. Use a fan + some sort of duct to force air under the door. According to the article here, from what I understand, door undercuts can work. I am just not sure what to look for to begin to build or install something like a door undercut fan duct.
  3. ??

Any other suggestions are welcome as well.

2 Answers 2


Install a room to room transfer fan in the wall at the bottom of one side of your wall, and install an intake louver at the top of the other side of the wall in the same stud cavity. The reason for the high/low setup is to help reduce noise from transferring between rooms.

An example product that would work for this is here: Tjernlund-AS1-AireShare-Room-to-Room-Transfer-Fan

Example image

  • Thank you for the suggestion but unfortunately, I won't be able to implement it because it's a rental. I was hoping for a solution that's not too invasive but I understand that I didn't make it clear.
    – mmtauqir
    May 3, 2019 at 0:33

Have you considered just increasing the gap under the door to 1cm or 2cm and putting a fan to extract air from the room into the roof space?

You would only need to have a small fan - even a 4" fan from a computer power supply (although there are quieter ones, or reduce the voltage a bit) will create probably sufficient air movement.

  • Oh I'll test that for a few days to see if it helps.
    – mmtauqir
    May 3, 2019 at 0:32

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