Summer Cooling with exhaust fan

I have a 24'x24' shop with a one car garage door shifted to one side at the front. It has one door at the side and another at the back. One 2'x4' window on each wall that can be opened half way. The ceiling is open but after I insulate and finish the walls and ceiling I will have a ceiling that is roughly 10.5' tall.

I have been looking at placing an exhaust fan at the back to pull air through the shop and cool it down with a nice breeze during the summer. The websites I have looked at use the following calculation: Area (in square feet) * Ceiling Height * 0.5 = the required CFM of the fan. I feel that this formula gives you the required CFM if the doors were not open. I would like to have the garage door and windows completely open and still feel a breeze being pulled through the shop. Can anyone give me some recommendations on what CFM I should be looking for.

Well were are you located, I’ll assume toward the beach? Maybe not : )

Which way is the prevail wind? Which way is all the windows and doors located to the prevailing wind? Hopefully you won't be trying to vent into the wind.

What is the construction type is the roof line, A-Frame ? Maybe even a slopped roof?

Since your going to close in you ceiling, I’d suggest that you put your fan up in the attic and install motorized louvers or open grates thru the ceiling.

Here’s why, that whole-house building fan will be loud and by this design will dampen the noise or at least muffle and help hush the noise that it will create! The fan in the attic/craw space ceiling will also add in preserving an asphalt roof, and vent the craw space as well. I say loud cause I could easy be a 4 x 4 fan - belt driven.

If it only bar joists or a low profile roof trusses you could still do this, but you might need just a roof fan vent maybe two, on the side of the building, but you might create some whistling! Side venting fans might be a little costlier over all.

You could also just grate and vent right through the roof, if tin! The fans come on the grates open, close they shout. I'm thinking two or three ceiling louvers. 2x 2 or 3x 3 louvers. Of course if you side install your have to protect from the weather.

If your not going to use the high ceiling, I think I’d just get some low profile pad fans, I would not get remote control models, I’d keep the control in the switch box. No matter what I'd keep all the future controls together.

If shingled roof you can get the venting requirement of what the manufacturer desires to extend there life off of the package at the hardware store, or Google can be your friend as well.

Barring any building codes due to what your doing in the shop it might all be a go.

Just some thoughts, hope that helps.

I got the idea a couple of years ago to go looking for a solar powered gable fan for my house here in San Antonio. Found one on E-bay from a company in AZ. I just went to a CostCo in FL and saw they had a set up like I got for only $279. I really think that the one in my house made a big difference.

pearlsnap said:

I have a 24'x24' shop with a one car garage door shifted to one side at the front. It has one door at the side and another at the back. One 2'x4' window on each wall that can be opened half way. The ceiling is open but after I insulate and finish the walls and ceiling I will have a ceiling that is roughly 10.5' tall.

I have been looking at placing an exhaust fan at the back to pull air through the shop and cool it down with a nice breeze during the summer. The websites I have looked at use the following calculation: Area (in square feet) * Ceiling Height * 0.5 = the required CFM of the fan. I feel that this formula gives you the required CFM if the doors were not open. I would like to have the garage door and windows completely open and still feel a breeze being pulled through the shop. Can anyone give me some recommendations on what CFM I should be looking for.

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I am not sure what the cfm needs to be, but if you want your doors open all the way you're going to need one hell of a fan to feel a breeze through an open garage door. Put the fan as high up in the room as possible, so you are sucking the warmest air out of the space. your best bet is leaving the door or window on the oppposite side of the room furthest from the fan location. that way you will be pulling the air across the room, feeling the breeze. think about a vacuum, the smaller the hose (opening) the harder the suction will be.

Thanks for your replies. I am in Texas just east of the Dallas area.

More info on my shop: I am not real familiar with building terms but I will do the best I can. The shop is built using 2x4s and has a sloped shingled roof. The truss of the roof is what I think is called a scissor roof truss. It is 9'8" high at the walls and around 10.5-11 foot tall at the center. I think the tallest point of the roof is around 20 feet tall.

Not sure which way the prevailing winds are but the garage door is facing south.

I got the idea of doing this from a shop I worked in during college. It was a very large shop (around 5000 square feet). The ceiling was taller than a two story building. There was one rollup door at the front and one wall had windows that tilted out. There were three large fans on the roof that when we turned them on would create a breeze through the shop that would cool down the hottest summer days. I was hoping to simulate this on a smaller scale with my shop.

Maybe with the garage door open it is just wishfull thinking but hopefully it can be done with maybe the windows open, and possibly the doors as well. My initial thought was to just take a fan that would circulate the air once per minute (6000 CFM) and mount it on the north wall opposite the garage door. Depending on the size of the fan I might have to install louvers that open once I close in the ceiling.

Thanks again for your help.

Your summer prevailing winds will be from the S to SE. I would consider a whole house fan pulling up into the attic. A big whole house fan should do what you want and help keep temps down when your roof deck reaches 150F+ in the Texas summer. It would be somewhat better if there was a door on the north end to pull in cooler air from the shaded side of the garage.

http://www.homedepot.com/buy/buildi...w/whole-house-fan-30-in-belt-drive-78386.html

http://reviews.homedepot.com/1999/1...le-house-fan-with-shutter-reviews/reviews.htm

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I do have a door on the north end just not a garage door.

So for a whole house fan it would be mounted in the ceiling, pulling air up into the attic. Would I need to have vents in the attic area to the outside? Sorry I am just not familiar with whole house or exhaust fans.