Capturing Cold Air from the Basement

[iamsoners]

The days are getting hot here in the midwest.  We're going into our first year in a new rental and I'm wondering if anyone has advice on how to pull some of the cold air up from the basement.  It's a two story house with a walk out basement and I went in the basement this afternoon and it was at least 20 degrees cooler than upstairs.  Can anyone think of ways to pull the cool air out and into the upstairs?  The door and a box fan is one idea but the door isn't in a prime location for that.  The forced air vents are all under the floors and vent in to the upstairs portion but I imagine opening them up in some way is not a good idea for a rental.  The ceiling in the basement is open, which might provide options.  Any ideas?

[reverend]

Weeeell, you said it's a rental, so installing a whole-house fan or attic fan is probably out of the question.
You could cheap out and stick a fan in a window blowing OUT, somewhere on the top floor, then crack a window in the basement.  That will do the trick.

Do you have a recirculating mode on the furnace where just the fan blows air around without running heat or A/C? That will move the air around a bit too.

[Mactrader]

This is interesting to me as well, but it's my house. What can we do to bring up that nice cold air that's just being wasted in my basement? How would an attic fan bring up the cold air? Is there anything clever I can build/rig to do this?

[reverend]

What you're doing is cracking a window open in the basement, then the attic fan pushes air from inside the house up into the attic where it exits via the vents.

This pulls the cool outside air in, along with cool basement air, circulates it through the house, then pushes it up into the attic. It cools the attic down so the sun now has to heat a much cooler attic during the day, and introduces fresh, cool air into your house to keep it cooler too.

In the morning, you turn off the fan, close the downstairs window and head to work.  In the evening when the outside temps drop again, you crack the window and turn on the fan.

Since hot air rises, you're helping the convection along, you drop the temps in the house and attic meaning it takes longer to heat during the day and you might not even need the A/C (not in Colorado, for sure).  Using an attic fan in conjunction with thermal blinds is very efficient too.

Things to consider - when it gets cold in the winter, is the fan insulated by lids so you don't get cold air INTO the house via the fan opening?  Is the fan too loud to run at night so you can't sleep? Power consumption of the fan?  Are you allergic? It will suck in pollen in the spring (depending on where you live).
Several of these are mitigated by a high quality fan manufacturer. The allergies depend on you and where you live.

If you're really allergic, then I'd go with a recirculating system in the house where all the air passes through filters and a filtered heat exchanging system to introduce fresh air. That way you can keep the house closed up and sealed tight.

[velocistar237]

I saw something about this.

My Inexpensive “Do It Yourself” Geothermal Cooling System at Trees Full of Money

One thing you would want to watch for is air quality. We have a gas dryer and gas water heater in our basement, and it's pretty dirty down there.

[BenDarDunDat]

I saw something about this.

My Inexpensive “Do It Yourself” Geothermal Cooling System at Trees Full of Money

One thing you would want to watch for is air quality. We have a gas dryer and gas water heater in our basement, and it's pretty dirty down there.

I wonder how effective it would be if you bought an inexpensive ductless split system and placed the outside unit in your basement and blower unit in the house? As long as you weren't using the basement and provided the basement had enough radiant power, you could have a geothermal system for a fraction of the cost.

[Mactrader]

What you're doing is cracking a window open in the basement, then the attic fan pushes air from inside the house up into the attic where it exits via the vents.

This pulls the cool outside air in, along with cool basement air, circulates it through the house, then pushes it up into the attic. It cools the attic down so the sun now has to heat a much cooler attic during the day, and introduces fresh, cool air into your house to keep it cooler too.

In the morning, you turn off the fan, close the downstairs window and head to work.  In the evening when the outside temps drop again, you crack the window and turn on the fan.

Since hot air rises, you're helping the convection along, you drop the temps in the house and attic meaning it takes longer to heat during the day and you might not even need the A/C (not in Colorado, for sure).  Using an attic fan in conjunction with thermal blinds is very efficient too.

Things to consider - when it gets cold in the winter, is the fan insulated by lids so you don't get cold air INTO the house via the fan opening?  Is the fan too loud to run at night so you can't sleep? Power consumption of the fan?  Are you allergic? It will suck in pollen in the spring (depending on where you live).
Several of these are mitigated by a high quality fan manufacturer. The allergies depend on you and where you live.

If you're really allergic, then I'd go with a recirculating system in the house where all the air passes through filters and a filtered heat exchanging system to introduce fresh air. That way you can keep the house closed up and sealed tight.

Sounds like I'd need to get some new infrastructure in my house to do this. I may have to check it out though, I don't have an attic fan currently, and in all of my old houses the fan always blew out my pilot lights in the basement! Maybe that's because I didn't crack a window in the basement...

[sideways8]

My parents used to just use two box fans- one at the bottom of the basement stairs pointing up, and another at the top of the basement stairs pushing the cool air into the livingroom. Maybe not the best solution but perhaps that could hold you over until you get something more efficient in place.

[reverend]

You must have had a pretty decent air leak into the house to blow out the pilots without any windows open. :)

Read up on how these guys build houses. It's informative. If you buy a fixer-upper that you have to gut anyway, then this is definitely the way to go!

http://www.imaginehomessa.com/

What you're doing is cracking a window open in the basement, then the attic fan pushes air from inside the house up into the attic where it exits via the vents.

This pulls the cool outside air in, along with cool basement air, circulates it through the house, then pushes it up into the attic. It cools the attic down so the sun now has to heat a much cooler attic during the day, and introduces fresh, cool air into your house to keep it cooler too.

In the morning, you turn off the fan, close the downstairs window and head to work.  In the evening when the outside temps drop again, you crack the window and turn on the fan.

Since hot air rises, you're helping the convection along, you drop the temps in the house and attic meaning it takes longer to heat during the day and you might not even need the A/C (not in Colorado, for sure).  Using an attic fan in conjunction with thermal blinds is very efficient too.

Things to consider - when it gets cold in the winter, is the fan insulated by lids so you don't get cold air INTO the house via the fan opening?  Is the fan too loud to run at night so you can't sleep? Power consumption of the fan?  Are you allergic? It will suck in pollen in the spring (depending on where you live).
Several of these are mitigated by a high quality fan manufacturer. The allergies depend on you and where you live.

If you're really allergic, then I'd go with a recirculating system in the house where all the air passes through filters and a filtered heat exchanging system to introduce fresh air. That way you can keep the house closed up and sealed tight.

Sounds like I'd need to get some new infrastructure in my house to do this. I may have to check it out though, I don't have an attic fan currently, and in all of my old houses the fan always blew out my pilot lights in the basement! Maybe that's because I didn't crack a window in the basement...

[kudy]

I vote for the series of box fans set up at strategic locations.

[Welmoed]

. We have a gas dryer and gas water heater in our basement, and it's pretty dirty down there.

If you have a gas water heater, you need to be extremely careful about messing with negative pressure. Since a water heater's exhaust relies on natural drafting (i.e. there's no fan to keep the exhaust moving, like there is in the dryer or a high-efficiency gas furnace), if you use an attic fan to create negative pressure in the house, you could very probably cause backdrafting in the water heater, which could lead to dangerous levels of carbon monoxide (CO).

If you choose to try it anyway, please make sure you have a reasonably new CO detector set up near the sleeping areas.

--Welmoed the Home Inspector

[Guitarist]

When thinking of your home air environment, just remember, the AC, the heater, all it is is the movement of heat. Whether you are adding or taking it away.
So, the idea of opening an attic window with a fan blowing that air out, coupled with opening a basement window with a fan blowing that air in, is a good, simple one.

I'd also take a look at your humidity. The lower it is in the summer, the better. The higher it is in the winter, the better.
I think dehumidifiers are rather expensive so it may not be worth it, but having a humidifer in the house over the winter will keep the heater from running as long and as often.

[trammatic]

For us, setting the A/C fan to "on" instead of "auto" did the trick...in the summer, we just open the returns in the basement and vents upstairs.  In the winter, it actually got too hot up in the bedrooms, so we reversed it and had the returns in the bedrooms open and the vents on the main level open, so it would suck the hot air out of the top floor and blow it down to the main level where the thermostat lives.

If you try one of these tricks, you have to make sure that there is an easy path for the air to follow...  If you're trying to exhaust through a bedroom, the door has to stay open or else the fan won't actually move much air.