Cooling without AC

[snrusnak]

Hello everyone, this is my first post

I have a 1200sf shop (metal building, with thin insulation). It is 30' wide x 40' long and if I remember correctly 14' tall in the center and 12' tall at the sides. There are no vents. It has a big roll up door, I believe it is 10' wide by about 10' tall.

I'm in mississippi on the gulf coast where the summer/fall are extremely hot, and it is very humid. The head index a few days ago was 117

I have a slight gap at the top of the roll up door, about 2" wide. I wanted to get some thoughts from you guys.... If I install a somewhat large vent fan on the opposite end of the shop from the roll up door, near the ceiling, do you think having it operate on either a thermistat or humidistat would help keep it cooler and less humid? My thinking is it would draw "cooler" air in from outside, in through the door gap, and out the vent. Then I could also wire a on/off switch so when I'm working in there I can open the door and flip it on and have a good cross breeze with the door open.

Thoughts?

I'm not particularly interested in air conditioning it if I don't have to. I don't mind working in (reasonable) heat, but 117 heat index is too much lol. Also, the humidity is a relatively big problem. Causing mildew.

Thanks in advance. BTW, I was looking at this fan: It's cheap, has good reviews, moves decent air, and is simple to install (And replace if need be).

http://www.drillspot.com/products/48483/air_vent_inc_apg_automatic_power_attic_gable_ventilator

 

[Alchymist]

Don't think a fan will help a whole lot. If you are drawing in air high in humidity, the inside will be at the same humidity level. Likewise drawing in 90° - 100° air, building will be at that temp. It will tend to cool the building some, as radiant heat from the sun will cause the interior to be hotter than outside air.

 

[zmaxmotorsports]

Youll get air movement atleast,wont help with the humidity though.

 

[hewey]

How much cooler is the air outside than inside the shop? As a general rule yes having a vent at the top of the shed to expel the hotter air will help, if you have this at the highest point naturally hot air rises so it helps purge the hot air.

Can you look at other things like planting trees along the sunny side to help shade the building?

 

[snrusnak]

Thanks!

I do have trees around the shop, I'll take some pictures when I get a chance and post them.

I figured having airflow would help keep it from being stagnant, and help with humidity. I'll have to put a thermometer in there and see what it gets up to, but it has no vent currently and is very hot. Outside air is pretty hot these middle months, but definitely cooler than inside, especially in shade. Do yall think it would be worth the $80 to buy the fan and install? I think venting it in general is a good idea and will only help to make it feel cooler.

Next option is air conditioning. I really wasn't excited about this due to the cost, but what would it really cost to AC a 1200 sf shop??? I'd probably keep it set pretty high, maybe 80 deg F or so. I currently pay about $80/month for my electric bill in my 2400sf house (all electric, no gas). I hate to spike that rate through the roof as it's currently pretty reasonable.

 

[snrusnak]

I took some pictures. I'd love some input from you all, I have an idea and would like to know how well it'd work...

The roll up door and man door are on the east side (absolutely no shade)


The brick pile is on the north side (fairly shaded) There is a second photo of this side also, it's the one with the little pine trees/bushes. I eventually plan to build a lean to on this side, full length of the shop, to park trailers and such under.




The sycamore trees are on the west side (a lot of shade)


The chicken coop is on the south side (fairly shaded)


I originally wanted to put a fan up high on the west side to get a cross breeze when the roll up door is open, but this seems counter productive now that I think about it. The sun rises in the east and there's no shade there, so I'd be sucking in hot air most of the day.

I'm now thinking I can put two vent fans up high on either side of the roll up door, and have a louvered vent down low on the west side. This way I'll be sucking in "cool" air from the west side all day while it's in the shade and exhausting the hot air on the hot side (east). Even in the afternoon the west side is well shaded. So this seems to be my best option as far as air circulation, at least in my mind.

What do you all think? (There's not enough room above the roll up door for a single fan, that's why I was thinking two fans, one on each side.

Any help appreciated!

 

[72Anthony]

I'm in Houston, so I understand the hot humid climate.

In a previous house, we installed a similar type of fan to help ventilate the attic of a 1,600 sq ft house. The fan was bought at Home Depot, and looks to be about the same size. It had a thermostat and would come on around 2 pm and turn off around 7 or 8 pm in the summer. I don't think it made much of a difference.

I don't think one of two of those relatively small fans is going to cut it: 1200 sq ft X 12 ft ceiling = 14,400 cubic ft. Divide that by one of those fans at 1620 cfm = 8.9 air changes per hour. The problem is there is a small difference between the hot outside air and hotter inside air. You need a lot of air flow to overcome that. Imagine if your car is in the sun all day, say 140 deg F inside and the air conditioner only put out air at 90 deg F instead of the normal 50-60 deg F, it would take forever for the temperature to drop and it would still be uncomfortable.

What type of insulation do you have on your roof? You may want to consider some type of radiant barrier (paint, foil, rigid board with foil) to reduce the heat gain into the building.

 

[snrusnak]

The roof insulation is the same thin stuff that's sandwiched into the walls.

See, I don't necessarily agree with what you're saying about the fans being effective. Maybe this isn't the proper fan, but our 2400sf house has 3 gable fans on seperate thermostats. I think I have them set at 90 F. The west one (must be set slightly lower) runs pretty much from lke 11am to 5 pm or so. The east one runs maybe a couple hours a day, later in the day. The 3rd one on the south, (carport) side, runs even less. They seem to help A LOT. The attic isn't anywhere near as hot as my house in Florida was, that just had ridge vents.

We also have extra louvered vents under the carport and front and rear porches though, for increased cool air flow up into the attic. Like I said above also, our electric bill is only about $80/month in this big house. I think the attic fans help keep that there. Our 1300sf house in FL had an electric bill double that. Other things play into this of course, but I think the fans help a lot.

Is the consensus that the air flow in my shop won't help much?

I can get bigger fans if need be.

 

[930dreamer]

You need an A/C system to remove the humidly to cool the shop. I live in the Texas Panhandle and a swamp cooler does very little to drop the temp in my 30x40 shop.

 

[crab]

Sometimes there just isn't a cheap way out. I really wish I had put a couple windows in the garage when we built. When it's to hot out there I don't go out there, that's the cheapest solution.

 

[snrusnak]

I went out to the shop around 8am and the thermometer was about 80 deg F. When we finished the rear lift on the jeep around 1130am it was about 95 deg F

Around 8am I also walked outside to the west side of the shop and it was nice and cool over there. I think I"m going to put these fans in. It has to help to some extent. If venting stagnant, hot air out didn't help they wouldn't put vents and fans in attics.

 

[snrusnak]

Here's a few pics of the inside of the shop:









It's a mess...

 

[dsimatt]

I've got no real advice but that's a nice shop an I'm jealous.

 

[snrusnak]

Thank you! I came from a tiny two car garage and never dreamed I'd get to a point where I'd have this big shop. I love it, but I need to get it set up properly so it's not full of **** laying on the ground. My brother and I also like to brew beer out there, and I'm thinking of building a 15' x 8' air conditioned room inside. This would be a "brew room" and I could keep anything else particularly finicky with humidity in there... Biggest problem right now is I don't really have a lot of money to spend on the lumber and what not for all that. When I do it I want to do it right.

One of these days I'l get to building that F100 in there, and I also have my buell that I haven't ridden 1 mile this whole year....

 

[dsimatt]

My garage is a disaster right now and its just a normal 2.5 car garage, I know what you mean not having money because theres a lot of projects I want to get to but am short on funding.

I don't have ac in my house and have been very tempted to just slam a thru wall unit in my place as I'm miserable but my Grandpa always taught me that if you're gonna do it, do it right the first time.

 

[snrusnak]

I'll second that. Everything I've ever done in a shortcut fashion I've very quickly regretted...

No AC can be ok depending on conditions. All spring and summer we turn it off and open the windows and get an ice cross breeze. It feels great. But I don't know that I could do without AC in this 100-120 heat index summer lol. I'm sure a whole house fan and open windows and fans would be tolerable. All depends on how you manage what you have.

 

[dsimatt]

This summer was decent that I could air my place out at night and cool it down, today was the first time it hit 80 inside but its the humidity that makes it miserable.

I have hot water heat so that complicates putting in a/c and its hard to justify the high costs for only a few months a year but right now it would really be nice but I have other more important things ahead of that.

 

[snrusnak]

It was 100 deg in the shop today at 4pm. Humidity was surprising at about 50.

 

[pseudorealityx]

It was 100 deg in the shop today at 4pm. Humidity was surprising at about 50.

It's not surprising at all. People don't seem to understand that RH is exactly that.... relative. 50% RH at 100 degrees is the same amount of moisture as 100% at ~78 degrees.

 

[DEnd]

Thanks!

I do have trees around the shop, I'll take some pictures when I get a chance and post them.

I figured having airflow would help keep it from being stagnant, and help with humidity. I'll have to put a thermometer in there and see what it gets up to, but it has no vent currently and is very hot. Outside air is pretty hot these middle months, but definitely cooler than inside, especially in shade. Do yall think it would be worth the $80 to buy the fan and install? I think venting it in general is a good idea and will only help to make it feel cooler.

Next option is air conditioning. I really wasn't excited about this due to the cost, but what would it really cost to AC a 1200 sf shop??? I'd probably keep it set pretty high, maybe 80 deg F or so. I currently pay about $80/month for my electric bill in my 2400sf house (all electric, no gas). I hate to spike that rate through the roof as it's currently pretty reasonable.

If you aren't out there in the middle parts of the day then a fan is an option. Once the temps start getting to around 92ºF and up a fan will either not help you or make you hotter, depending on where your Relative Humidity is. 92ºF at 100% R.H. in the shade increases your body temperature, and is eventually deadly. Fortunately for us it doesn't stay that hot long enough.

As for how much it costs to add and operate A/C that depends on how much you want to spend. The more you spend on preparing for the A/C the less it will cost to operate. You can spend anywhere from a couple of Thousand on up for an A/C system, but any system you buy in order for it to run cost effectively you need to air seal and insulate your building, that will again be a multi thousand dollar prospect.

Your cost to operate an A/C system depends entirely on how many BTUs (a measure of heat energy) you have to remove from your space. A lot of contractors size their systems by the 500 square feet per ton, so your space would need a bit over 2 tons of Air conditioning (meaning the unit can remove 24,000 BTUs per hour). Without adding insulation this is too little, with a good amount of air sealing and decent insulation levels this can easily be too much. But lets say you are able to put in a 2 ton 13 SEER (SEER is a measure of Air conditioning efficiency) system and need to operate it 4 hours a day. I see Mississippi has an average electricity rate of 10.3 cents per kWh ( a measure of energy) operating that system 4 hours a day would mean you would pay about $23ish a month (assuming the unit was able to meet its SEER rating 100% of the time).

 

[AndyCBR]

OP,

I had built a similiar size shop years ago where I used to live. To get enough air movement to offer any help I installed 2-48" Dayton exhaust fans in the wall up high when the place was built. They weren't cheap and I had to get louvers for the outside to keep the place closed up. I got them from Grainger at the time (15 years ago) and I shudder to think what they would want for them now.

When they were both running and I closed the overhead doors within 2 feet of closing there was a healthy amount of air movement that helped quite a bit.

The noise was not objectionable but again, it wasn't a cheap solution but a step below trying to air condition such a large space.

Several people in other threads have mentioned using a dehumidifier or two to keep the humidity lower inside the space and then the A/C doesn't have to work quite as hard which makes sense but that all goes out the window once you start drawing the outside air in with a fan. I still think a dehumidifier would help your mildew problem whether you air condition or not.

 

[DEnd]

OP,
Several people in other threads have mentioned using a dehumidifier or two to keep the humidity lower inside the space and then the A/C doesn't have to work quite as hard which makes sense but that all goes out the window once you start drawing the outside air in with a fan. I still think a dehumidifier would help your mildew problem whether you air condition or not.

the dehumidifier would only really wok if he can adequately air seal the space. Otherwise it would just run all the time and have very little effect on the overall humidity in the space.

When you dehumidify the space you create a vapor pressure differential, this will pull outside humidity in through all the air leaks in a building. As leaky as his building is (air wise) he would basically be trying to dehumidify the outdoors.

 

[pseudorealityx]

92ºF at 100% R.H. in the shade increases your body temperature, and is eventually deadly. Fortunately for us it doesn't stay that hot long enough.

Fortunately, that kind of condition basically doesn't exist... It's off the graph on common psychrometric charts. The most extreme air conditions you'll see in any part of the USA for any sort of sustained time is ~100% RH at 84ish, so up around 170 grains. In comparison, typical room temperature is ~65 grains.

92 @ 100%RH would be 233 grains, or 40% more moisture than you'll ever see.

 

[snrusnak]

Thanks for all the input!

Here's a few things I've been thinking over the past couple days:

There's no way I can AC my shop any time soon. I don't have the money to do it in the next several years.

I need to do the best I can do with fans at least for now. I bought a cheapo thermometer and humidity device to at least get an idea of what's going on in there and have been paying attention throughout the day as to what the temps are, where there's shade, etc. At night, the humidity is high. During the day it is normal. I never go in during the day due to working at my real job, but I do get home "early". I have a flexible schedule and get home anywhere between 2:30-4:30 on a normal day. It's still pretty hot out at this time. Currently, I usually want to go work on something out there, but the heat turns me off. I do all sorts of work, autos, motorcycles, house projects, yard work, very very rough "woodwork", welding, etc. Sort of a jack of all trades, but I like to think I'm a master at many lol.

If I can get a fan setup (permanently mounted up in the "gable") that will keep the shop circulated and vented, then have a "personal" shop fan blowing on me while I'm working, I'd be happy. I worked all this weekend out there with a heat index of 108 without any air circulation. My shirt was so wet when I was done it literally looked like I jumped in a pool. I can tolerate heat, but that is a bit extreme. If I can tone that down a bit with fans I'm happy.

I'm willing to spend a little money (what I can afford) on good sized fans if it will really help. My budget is probably realistically around $500 at least for now. If I can spend a little more and do something that will be very beneficial, I can hold off and do it in a few months.

Just a few other notes, the shop is actually insulated, with that thin matting. It's definitely not sealed, and I don't really have intentions of sealing it. Something else adding to the humidity issue is the roll up door doesn't seal perfectly due to a slight crown in the concrete. I replaced the seal and it is 10 x better, but a slight amount of water will sometimes get in and then of course evaporate and is stuck in there. It used to be a lot of water getting in. Since I made the seal better, I actually haven't had any mildew issues, at least nothing that's a big deal.

 

[Super Mech]

My shop was 94 at about 1pm today. Tomorrow is gonna be worse, humidity and temps will be higher than today. I have 3 industrial pedestal fans going with a large skylight open. If it's too hot I'll close early. I retreat to the office several times a day for some air conditioning.

I can guarantee that I will have a rain forest under my nuts by lunch time!

 

[snrusnak]

You need duluth trading company armachillo underwear They are expensive but man oh man are they worth it. I work at a plant and even though I'm technically an "office guy" I spend a lot of my time out in the field. One of our building's is probably somewhere around 130-140 deg and those armachillos are seriously well worth the $25. I bought them just for work.

 

[DEnd]

Fortunately, that kind of condition basically doesn't exist...

True but I was using it to illustrate the point that during summer in the humid south that air movement alone won't cut it at times. If he plans to really work in his shop during those times he needs to plan on some sort of A/C.

 

[Ray916MN]

I have to wonder whether the most effective fan strategy might be to run venting fans and open the building up after the sun sets and then to close it all up before the sun rises to lower the temp in the building as much as possible when it is cool overnight. With the coolest air in the building then, you might try using fans to blow air across the concrete floor to use the lower ground temperature to keep the air in the building as cool as possible and maybe run a dehumidifier to try to knock the humidity down.

The problem with the approach is the heat from lighting, fans and dehumidifier and inability of the insulation and tightness of the building to keep heat out will likely mean the temperatures in the building will ultimately be at least as hot as the outside temps, but if you achieve that with lowered humidity, it will be more comfortable in the building. And at the very least it should be more comfortable to work in the morning hours in the buildings without having to spend allot.

 

[GTOExtreme]

True but I was using it to illustrate the point that during summer in the humid south that air movement alone won't cut it at times. If he plans to really work in his shop during those times he needs to plan on some sort of A/C.

I agree. You can't chance it in the summer. I live in the South and it is so humid down here. Installed a couple of window units in my shop (plus the big shop fan). It is pretty cool in there for the most part except on those 100+ degree days.

 

[stihlntime]

Look at Porta Kool units. They are quite effective. Just a old time portable swamp cooler. The colder the water in the tanknthe cooler the air being output. Lots of how to make one DIY info on the net. Just takes a fan,a circulating pump,chicken house cool cell material, and water container.

 

[snrusnak]

Well, unfortunately, I just am not able to afford air conditioning the shop. I have a mortgage and student loans, etc. Things are tight enough as it is lol.

As I said, the shop actually IS insulated. I looked again this evening and really sealing it up "air tight" wouldn't be that hard. It's basically just the for top corners where they left a small gap. Some expanding foam insulation would do the trick. Other than that, it's just the roll up door which there's not much I can do there.

I plan to install lights at some point just for evening work, but the shop has two "skylights" ("clear" fiberglass panels) that actually provide ample light during the day, especially with the roll up door open. There is currently just one light bulb setup just inside the man door, and it doesn't do much.

I'm not really a fan of the dehumidifier just because even though it reduces humidity, it just adds more heat. Helps a little in one spot, hurts in the other. And with the building not really sealed up well, I don't see that being effective.

As for a "swamp cooler", doesn't that just add humidity? I had thought about making a coil out of copper with my ground water running through it (it is pretty cold even in 100 deg days) but thought that would just add humidity...

I've actually found less mildew/humidity problems this summer than last winter. This is due to the door sealing issue I mentioned above. If I can achieve something just a little better I'd be happy.

 

[jvitez]

Yes, swamp coolers do add humidity. That's why they were popular in the southwest years ago. But it's not the right thing in the humid South.

 

[JCoggin]

Take a look here. These systems work!

http://www.sprinkool-systems.com/

JC

 

[CNGsaves]

Vote to bring in cool nightime air and push out hot air in shop from day before. Since insulated shop, then keep it closed during hottest part of day. Run big fans in shop during day to circulate and lessen humidity.

I'd be watching CL for whole house A/C systems removed while still working fine. These can range from $250 to $1000 for 2.5 to 4 ton systems. Put in some ductwork to concentrate the cooling where you'll be working.

+1 that you've got an AWESOME shop . . . pristine yard as well !!

 

[Radix2]

Fans are a good idea in any case to reduce mold and mildew - keep it on low even when you are out.

 

[snrusnak]

JC, do you really think that system works? The reason I ask is that I actually have sprinklers on the roof of my house that the prevous owner (also the builder) installed for that same reason. He disconnected them and told me they didn't help at all. So I'm curious of other experiences...

What do you all think about buying a couple 24" floor fans, like this:

http://www.harborfreight.com/24-inc...3115b&utm_source=1021&cid=mEmail_s1021_c3115b

Then making my own mounting brackets and mounting them up high on the wall. $110 per fan vs $77 per fan but they move over 4x the cfm. Is there any reason not to do this? Are there any safety impacts? Like maybe the actual true gable fans have overheat protection and these don't? If there's no real difference, I can add brackets easy enough and wire up my own thermostat.

 

[James-W]

Re: Cooling Without AC

Whenever you are trying to heat or cool a space, insulation is your friend. The more insulation you have in the walls and ceiling, the better off you are. If at all possible, I would increase the amount of insulation you have in the building.

I am sure fans would help to a certain extent because they create a breeze. But let's not forget the breeze is still the same temperature as the ambient air. Having a breeze blowing on you may make you feel a bit better, but it does not lower the air temperature and/or the humidity. You need air-conditioning for that.

If the work you do in the shop is making you money, it may be in your best interest to get a loan to get the place air-conditioned. If the shop is just used to work on personal "fun" projects, then a loan would not be a good idea, at least at this time. Maybe later when you get your debts paid off/paid down it would be a good investment, but not right now.

 

[snrusnak]

Well I understand fans won't actually lower the temperature below ambient but for example right now (9pm) the outside temp is 76 deg and inside the shop it is 91 deg. Even during the hot day the outside air is significantly cooler than in the shop due to it heating up all day, trapping the heat, and since it's insulated it holds the heat.

I'm going to start with fans and see how it is. I can't afford anything more right now anyway. Down the road maybe I'll have other options. So right now I want to get the most airflow I can for the money, but also don't want to do anything dangerous. Those fans say they have thermal overload protection, I don't see any reason not to use them... I know that's not their intended purpose, but why couldn't they be used for that?

thoughts?

 

[DEnd]

With your shop being metal it (the roof sprinkler) will help with the heat soak issue, the main thing is you are cooling outside of the insulation. Your insulation levels are likely fairly minimal however, mainly to prevent condensation on cool mornings.

My experience with those fans, is you really need to be somewhat near them. Though I think that mainly has to do with the air movement being so low to the floor, instead of at your upper body. I say get one and build a 2-3' stand on casters for it and see how that works (along with your gable vent fan), then you can play around with where you might want to have one permanently mounted.

A gable vent fan on a thermostat will help tremendously with heat soak in your shop, helping to keep everything in the shop at the outdoor air temp instead of say 120º. That combined with a good fan aimed at your torso near where you are working will likely keep things tolerable in your shop.

 

[James-W]

Even during the hot day the outside air is significantly cooler than in the shop due to it heating up all day, trapping the heat, and since it's insulated it holds the heat.

Insulation works both ways, it can keep the heat in, or keep the heat out. In your case, more insulation could help keep the heat outside. With enough insulation, if the temperature outside were to get down to 60 degrees at night and you opened the doors and let the shop cool down to 60 degrees, then you closed the doors and kept them closed, the inside temperature would stay pretty cool all day long.