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I'm trying to make my office less stiflingly hot during summer afternoons. My house is 2-story, and the corner of the office juts out into the main house, such that ~20sqft of its ceiling is under a ledge in the main atrium.

Some beautiful explanatory artwork - click for full size:

enter image description here

The black box indicates my office. The three walls of the office above the red line are either exterior brick-clad sun-facing walls, or border the garage. The red line is the exterior wall of the house, extending up to 2 stories. The red line is kind of a lie; it extends further to the right in this image, and the vertical red line is more a two-story interior wall.

The green shaded area is a ledge on top of the office, inside the two-story atrium of the house, that we put fake plants on. It's probably 20sqft or so, with 10ft+ of headspace.

Joists in the room run up-down in this diagram.

The room gets too hot in the summer, especially when we have to close the door. A well-placed fan in the top right corner helps quite a bit to circulate air iff. the door is open.

My crazy idea is this: If I could suck the hot air from the top of the room out, into the bigger atrium area, it'd help circulation in the room and generally cool it down. My proposal is in blue.

Is this a terrible idea? Some things I don't know:

  1. Does sucking hot air out of the ceiling of a room help much, in principle? I use a standing desk and I can feel the temperature bands, leading to this idea that sucking hot air out would help.
  2. Would I be better off trying to boost the existing HVAC vent? The rest of the house is fine, and the A/C unit is probably a bit oversized - it has no issues keeping up.

I've never seen this done before, which probably bodes poorly. What's the catch?

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I am assuming your proposed air passage is all interior and all within the same "air space" of the rest of the house.

Removing Risen Hot Air

Your vent would indeed help remove the warmer air that has risen to the ceiling. The replacement air is presumably supplied from the HVAC vent or from the doorway of the room.

Air Passage with Convection

You may even be able to implement the air passage without forced air, by natural convection alone.

In older stove heated homes there could be such a grilled passage to move air through the floor above the stove and into for instance the upstairs bathroom.

Simply cut a hole, and finish it. When cutting, always be aware of the potential wires and piping in walls & ceilings.

Include a Damper

It is advisable to have a damper, or a grill with shutters, to prevent the escape of warm air in the heating season.

Of further consideration is any noise traveling between the two connected spaces, either way: your phone conversations, visitors & TV etc.. For this you can build a noise-attenuating "sound maze", inserted anywhere along the duct, e.g. at either end.

And finally you could consider the travel of cooking smells from the kitchen, for which again a damper would be a good solution.

I doubt there is a building code prohibiting such a passage, since air passages are common in forced air duct systems such as the one you already have.

Booster Fan

As an alternative you could get a booster fan for the HVAC vent that you have. These fans integrate nicely with the vent, and operate automatically when the supply side temperature is above a heating threshold or below a cooling threshold. Additional air would be pushed in your office, and the return would be through the doorway as it probably is now.

Stir up the air

Use a ventilating fan to "stir up the air" for a more comforable mix. You definitely do not want the cool air of the room, resting near the floor, to be pushed out while leaving the warmer air in the room.

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  • Yep, all the same “air space”, under the same forced air system. This is excellent, thank you for all the advice. In summary, it sounds like this isn’t a blatantly terrible idea and I may see a difference with only the hole, no fan. I love the idea of (even marginally) cooling the room with zero noise. In essence I’d be improving the return air path from the room to the HVAC system.
    – user18944
    Aug 17, 2022 at 0:19

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