Pump cool air from basement to above (no existing vents)

put a box fan at the top of the basement stairs blowing up, it’s ugly but moves a surprising amount of air for twenty bucks

I don’t like this idea. Opening a basement window in the summer, you’re introducing moist outdoor air into a cool basement, which could easily lead to condensation and moisture issues in the basement.

I use to do this and it dried the basement out so the sub pumps never came on, warmed the basement to a more comfortable level and cooled upstairs substantially during the day. I’d turn it off at night and open windows upstairs to let the basement “recharge” for the next day.

Don’t place the fan in the window. Place it a few feet back. Venturi effect for the win.

That's what we had growing up and now have one in our house. As long as it's not humid they are nice. When it's really humid nothing feels good. The evenings we do run the whole house fan we shut it off once the house is cooled down where we want it. Meaning as soon as my wife says "I'm cold" I know it's the right temp for me.

it's 2026 and this guy is charging his basement I feel like such a chump.

Not long... The earth has a ton of heat energy and air has very little. If you're talking about a true basement, where you're underground, the air will always be colder than upstairs. The question is "how much will it lower the ambient temp in your home?" to which the answer is "Not nearly as much as you'd hope".

You're thinking of the Bernoulli principle, the Venturi effect is somewhat similar but quite different. With Venturi, a fluid speeds up when you narrow the path. With Bernoulli, the air blown out creates a low-pressure space behind it, causing more air to get sucked out than the fan blows on its own.

I had an old house with hot water radiators and no AC. I could have tried blowing basement air up the stairway, but then my main floor would have damp, musty smelling air. I figured it was better to just invest in a window AC unit. I was surprised at how much difference one 5K BTU window unit made to comfort on the main floor. Of course AC doesn't travel around corners or upstairs very well. So in subsequent years, I bought two more 5K BTU units. One for my bedroom and one for the upper floor.

Stack effect. It works.

Best to know your basement radon levels before pumping up basement air. I’m not saying borderline levels are bad but sometimes radon can be off the chart and need remediation, especially if you are going to vent it to living space.

Have you tried it? I put a big return vent in my basement ductwork just to try it out and it does work. Now there are caveats to my method but I will say the cold air return in basement works mighty well in spring / any not super hot day.

Open one window in basement and one highest in living area or bedroom upstairs (wherever you want to feel the breeze the most). Put a fan in the window upstairs facing out. It will draw air through the basement and up and out. Please try it, most people are skeptical but I assure you it works. You create a ‘chimney of cool air that goes through your house.

Yes it does and very well, but even better with only 1 window open at top and bottom. I have a 3 story house no ac and no humidity issues like a couple comments suggest. One window Open in the basement and one open on the third floor, it creates a huge breeze that cools the house. Even the finished attic with a hot roof maintains tolerable temperatures

Tape a furnace filter to the back and boom, 300$ air filter for 30$

I saw someone pointing a blower fan up into a clothes chute

You could put a lot of time, effort, and money into moving the air, but I suspect that you will not like the result. You could move a lot of air, but move very little heat. Air has a rather low specific heat. ( Google the term 'specific heat' ) IOW, there is very little energy contained in the difference in air temperature. ( This is why there are very few air-cooled cars. Most use water cooling because water carries way more energy than air. ) Much of your problem is that the upper part of the house is hot. Not merely the air in the house, but the house itself: the bricks, the boards, the drywall, the studs, etc. They contain way more heat than the air around them. If you want the upper part cooler, bite the bullet and install a real air conditioner. ( Err, nowadays, maybe a heat pump ) But don't try to move cold air up from the basement. There is actually very little transfer of heat if you do so.

It's not worth it. There are other threads on Reddit proposing your idea that point out it won't work. The basement air is usually humid and once you start drawing air out of the basement, how long until the air down there cools again?

whole house fan that vents through the attic space

Open your basement windows and open some windows in the highest part of the house. You can add a fan blowing out to one of the upstairs windows. Some people install whole house fans to ventilate air from upstairs out of the house, not worth if typically because you lose a lot of heat during the winter.

It’s currently 73 degrees outside (at night). My basement is 76. My living room by comparison is 72 with air conditioning. The air temperature coming from the mini split is around 55. I don’t think that blowing slightly cooler air is going to do much, not to mention that your basement isn’t a cold battery in the summer. Simple physics says that eventually whatever cold the basement had would be depleted. Don’t try and reinvent the wheel, get air conditioning or deal with the heat

I doubt that adding new ventilation ducts would likely cost more than installing some window A/C upstairs. A few fan wouldn't work, the cool air would be completely lost during transmission.

You could do a whole house fan. Open up a basement window, run the whole house fan, and it’s gonna suck the basement air into the house and the house air will go out into the attic

Put in a mini split, it will also help with your heating.

High humidity and radon are two main issues.