Cooling down an uninsulated shop.

[Steve Peterson]

I have been following this thread with interest, because I am also trying to cool my workshop, and provide winter heat. But just ventilation won't do the job; here in NC humidity is as big a problem as the heat. If I bring in outside air, I just bring in moisture. I put in a window AC/heat unit,

11000 BTU, and can get a nice, comfortable temperature. Now I would like to add insulation to cut operating cost, but it looks like it will cost over $500 for insulation, which will then need to be installed just below the roof on stringers that are 11' high. The fiberglass insulation that comes 24" wide is R-30. Does it make sense to put that much insulation in a space with two garage doors and nothing in the walls?

Steve

[Pat Barber]

I consider any $$$ on that electric bill to be money out the door. We currently pay over $30 for various "energy related" extras tacked on to the normal bill.

I suspose they could come up with a cooling number or a heating number, but the total bill will vary pretty widely from one area of the country to the next. Our current rate of .08 kwh is about average for the country.

The impression I got from Leon's message was that the "total" bill to be $50 per month, which I found unrealistic.

Edw>>$50 a month for heating and cooling ??? They must have

[mac davis]

I'm working in an uninsulated 2 car garage with a dark colored roof.. average temp in central Ca. in summer is about 102, so I feel your pain..

A few things that I've done to make it tolerable:

I hung one of those round floor fans from the roof beams.. blows hot air out of ceiling area and out garage door..

Cheap portable evaporative cooler.. (only works in low humidity areas).. it's up against the only window, blowing out... doubles as an air filter and picks up a LOT of dust..

I keep a LARGE travel mug handy with about a quart of ice water.. refilled often to prevent dehydration...

Wireless thermometer... this will sound funny, but it helps.. lol The main unit is on the work bench, the remote is on the patio, which is covered but has afternoon sun... It's amazing what a mental thing it is, to see that it's 1 degree cooler in the shop than on the patio..

It would be nice to have a larger, cooler shop, but it's all i have and I work in it year round..

mac

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[tom_murphy]

I had our builder install radiant barrier paint. They applied it on the underside (visible from the attic) of the roof decking. I'm also in Texas (Dallas area) where the temps are currently getting to the high

90's. I honestly don't know if the paint helps, because I have nothing to compare it to. My cooling bills are still very high, but who knows how high they'd be without the paint. We also did the blown cellulose insulation, which certainly looks like it would be more effective than the standard stuff. That attic still gets very hot so I'm thinking that the paint is not that great, or there was a problem with the way it was applied.

I have the same problem as the OP in my gara..shop. It's a three car garage with the metal doors facing west and it gets downright toasty in the late afternoon. I just added panels of of exterior sheathing (foil on one side, R5 value)and I really don't think it helped much. I'm now comtemplating an exhaust (or intake) fan arrangement of some sort. I have a side door which is currently unused and blocked by equipment, but I could utilize it for a fan. The door is near my shop area and I'm thinking I could set up a heavy duty box fan to pull in fresh air through an AC filter and crack one of the garage doors to allow the air to escape. That way I'd be pulling slightly cooler air from the east and exhausing it to the hot west side.

I could also install a window AC unit in that door, but I think the cost to operate it would be astronomical.

Tom

[John B]

Here's a couple of things that I have done to cool my shed. It's 40' x

20' approx. tin with a concrete floor. The temperature here in Kalgoorlie is usually above 30c in summer and it is not uncommon to have more than a few 45c days. Currently it's between 0 and 20c= bloody cold :)

1. Installed a whirlybird fan in the roof.
2. Hung shade cloth over the metal roller door.
3. Purchased 16mm chipboard cover sheets, about .00 each when they are available and lined the inside walls with pink bats between. I just started with the North wall and as material and money, became available continued on.
4. Started insulating the roof. Once again using 3-6mm cover sheets with bats. Also had some 2" styrene which worked wonders. As the roof is not completed you can certainly tell the difference when standing under a lined section to a corrugated iron section.
5. Placed an evaporative air conditioner in the wall, a freebie. It does it's job as we have a very dry heat.
6. Made awnings for the windows. As each of the above jobs took place a noticeable difference was made. A method I have seen done and am assured is rather effective is to cover the roof with shade cloth, with 6" spacers to hold it of the steel. Painting the roof white should not be rejected either. this can produce anything up to a 8c difference in temperature. Hope this will help some. As with all things money and time usually rule the day ;)

regards John

[tom_murphy]

Hey Steve, did you do any calculations on the BTU you slelcted based on the square footage and temperature? What's your square footage?

Also, let's say the shop has been closed up all day and you turn on the AC at 3:00 in the afternoon. What's the inside air temp before you turn it on? How long does it take the window unit to get the shop down to your "comfortable" temp? What do you estimate the operating cost of the unit to be?

Thanks, Tom

[bridger]

mine is an unsulated all steel building... and I live in Arizona. temps here have been above 100 for a couple of weeks straight. I have a cooler on a cart that I aim in the door when I'm in there and a powered ventilator on a thermostat sucking the hot air out the roof. together they keep the temp to a survivable inferno...

[bridger]

nope. mass absorbs heat. insulation slows it down.

a heavy brick wall will take longer to heat up than aluminum siding over frame, but it will hold that heat late into the night. insulation slows down the transmission of heat. add r80 in the form of fiberglass of rigid foam or whatever and the inside of the house will stay cooler longer into the day and cool down earlier in the evening.

[bridger]

install the vent through the roof.

[Steve Peterson]

My garage (shop - don't tell SWMBO) is 24' square, and the walls are about

11' high, supporting a standard ^ roof, no ceiling. So it is 576 sq. ft., and a lot of cubic feet. It gets morning sun, but there are trees on the west that start shading by midafternoon. The 11000 BTU AC can cool it down quickly, maybe 15 minutes, and the compressor goes off when it reaches the set temp. Biggest thing is it removes humidity, which is 90% today. It has only been in service for a week, so I don't yet know how much it costs. As I said, I am trying to figure out insulation.

Steve

[Unquestionably Confused]

on 6/29/2005 2:44 PM Steve Peterson said the following:

My shop is insulated and ~ 336 sq ft. I found a one year old 8600 BTU A/C for about $125 that I mounted thru-wall. Even though it's insulated, the shop really can heat up if the A/C is not on and it's hot outside. Still, I find that by flipping it on high, I can bring it down from the low 90's to a really comfortable (relatively speaking) 75 in about 10 minutes or so.

Nice feature on mine with the digital controls and remote is that if the unit's off (say in the morning) and I plan to work out there when I get home from the office, I can set the timer to kick it on in X (1-12) hours. If I plan to spend most of the day there, when I turn it on, I can set that same timer to turn it off in 1-12 hours.

I don't know what it will cost nor do I care. It's only going to be running when I'm out there enjoying it so... I'd be more concerned if it was running all the time when the shop's not in use.

I put electric heat in the shop this past winter (after 20 years of messing with an insulated shop heated with a Kero-Sun heater or Redi-Heater) and was able to set the thermostat to keep the shop above freezing and then bring it up to shirtsleeve temperature when I want to use the shop. Same thing: Uncomfortable to comfortable in about 20 minutes tops. We're total electric and I never noticed an increase in the electric bill.

[Tim Douglass]

I dislike the idea of a swamp cooler for a shop, just because it adds so much humidity. I *like* living in a dry climate - I haven't had to worry about rust on my tools for years.

I vote for ventilation as the best way to control the heat on a short term basis. A 1500 cfm hooded roof fan cost only about $100 IIRC. I'm looking at putting one in my garashop soon.

-- "We need to make a sacrifice to the gods, find me a young virgin... oh, and bring something to kill"

Tim Douglass

[D. J. MCBRIDE]

It's been my understanding that somewhere close to 80% of your insulating value comes from adequate attic/ceiling insulation(heat rises?). For as long as I can remember, in the Houston climate, HVAC technicians concern themselves almost exclusively with sufficient attic insulation; I doubt many homeowners are going to retrofit uninsulated walls (though I have just bid a job to that very thing).

[Robert Bonomi]

Note: if it is blowing _out_, you're not getting *any* cooling advantage from it. the 'coolth' is on the side that the air blows out of.

[mac davis]

I use a swamp cooler, but it blows out the window... it draws a little heat out of the shop, but mostly (if I clean the filter regularly) helps the DC keep the dust down..

I just ordered a solar powered roof vent and that should help quite a bit, especially in the evenings, to get the stagnant heat out of the shop..

mac

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[mac davis]

it draws some of the heat, especially with the window frame and screen getting cold and acting as a heat sink... the window is a slider that's only about 1/3 as high as the cooler vents.. it's mostly used for dust in the air, though.. it's a portable one with a cloth belt that wicks water up through the pan and blows air through it, so it does a pretty good job on dust..

mac

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[Prometheus]

IIRC, (and it was a couple of years ago) they were hooded. I believe there were some louvered vents as well, but I don't know if I'd trust those in a roof, especially after they've been in there for a couple of years.

[Prometheus]

It's not going to hurt anything! Obviously, the best thing to do is insulate the walls as well, but most of your heat exchange is occuring through the roof. While I wouldn't suggest it as a new construction technique, I redid a large apartment building with a "balloon-frame" (there may be another term for that, but that's the handle we used) several years ago. The *insulation* in the walls was nothing more than the stucco, drywall, and about 12 inches of dead airspace between them. The attic was well insulated, and the place was reasonably energy-efficient. Not as good as some other options, but it certainly wasn't terrible.

[Leon]

Correct. They use gas also, however we do have friends that bought one of their homes 4 years ago and their bills reflected Ryland's claims.

[Leon]

Well said Hax. Thanks for the technical details.