Best fan placement to move air through the house
Why Hacker News recommends it
Cited in cooling and fan-noise threads as a short video with actual data on fan placement.
What it is
Matthias Wandel uses anemometer measurements to find where to place a fan to move the most air through a house at night. He finds that placing the fan some distance back from the window works better.
Recommended by 4 HN commenters across 4 different months, 2021 to 2025.
What Hacker News said
Strong rec samldev · 2023-07 · on “Cooking Air Quality”
Matthias Wandel made a great video showing how it's better to place the fan a meter or two away from the window to get more air flow [this video]
Recommends spearo77 · 2021-07 · on “Passive radiative cooling below ambient airtemperature under direct sun (2014) [pdf]”
Matthias tries a few options and evaluates them– [this video] > Experiments and anemometer measurements to figure out where to best place a fan to optimally air out the house to cool it down at night.
Recommends nemacol · 2022-09 · on “Effects of grill patterns on fan performance/noise (2011)”
[this video] Matthias has an interesting video that is tangentially related talking about the distance of a fan to a window and air flow. While watching I was wondering how this interacts with PC case fans and if they are losing a lot of performance by being directly against the case.
Recommends Sweepi · 2025-09 · on “Noise cancelling a fan”
Since all comments seem to agree that noise cancelling wont work, 3 practical tips: 1. use the Bernoulli-Effect, aka get "up to 50+%"(depends on fan model) more airflow by placing the fan 0.2(0.5) - 1.5m away from the window. 2. Blow air out of the window, dont try to suck air in. 3. To avoid noise: Put the fan in another room and open the window in the room where you are. Video with data: [this video] (6 minutes)
Cites pshc · 2025-09 · on “Noise cancelling a fan”
apparently this is the source: [this video] The fan increases air speed at the centre of the rotor, creating a low pressure zone which then sucks in surrounding air. So it helps to place the fan away from the window (roughly far enough that the wind cone "fits" the opening).