Any cheap / free ideas to cool a garage?

[KrisZ]

If the outside temps are in the 100s, then you will not get the inside below that without an actual cooling solution.

The cheapest and most effective relief without installing an actual AC unit, I would suggest, is a fan with water mist. You can rig something up or buy something like this.

https://a.co/d/7aypnsf


Or this, which looks better to me since it looks like you can connect it to a water tap.

https://a.co/d/grFAVgp

 

[4WD]

You need a radiant barrier stapled to the top cords of the roof trusses with an air gap between the sheathing and the radiant barrier. Insulation shouldn't touch the radiant barrier. It's not expensive if you buy it from a builder supply.

Stapled mine to the rafters - left a few inches at the ridge vents …
Used the double foil/bubble - you need that bcs the air flow spaces will get the upper foil dirty - but the lower foil stays clean/efficient …

 

[Hohn]

I'd approach it from a physics perspective. The first thing is managing the heat gain. So that's the radiant barrier and such that others have described.

The second thing is to take advantage of the larger temperature swings you get in the desert. You need some thermal mass. Huge chunks of cast iron or stone or such can make a surprising difference. They absorb heat all day and then re-radiate it all night.

Keep a pile of old dumbbells or barbell plates or (better yet) some heavy machinery like a lathe or similar in your garage. As much mass as you can physically acquire and store.

 

[IndyIan]

I've never tried one, but a cooled vest could work, like one with pockets for ice packs. I think you'd have to be a bit careful you don't over cool yourself.
I do the opposite in the winter, and you can work down to 15-20F with bare hands and wrenches if your core is a touch warm and your body is shedding heat through your hands and feet.

 

[CarlB]

Define, "cheap." $1, 10s of dollars, hundreds?

 

[barbersurgeon]

By far the cheapest solution is to adjust your schedule for the duration. I think it's called siesta?

 

[ecotourist]

Correct, the only benefit of a fan is if it blows on you, allowing your perspiration to evaporate faster and providing a cooling affect to your body.

The only way to get below ambient is some sort of mechanical cooler whether it be DX or evaporation.

That's where the idea of sprinkling the roof comes in. Evaporation is a non mechanical way to cool anything, including a roof in the hot sun. And you could do that with minimal capital investment or running costs. [The OP was looking for low cost solutions.]

People used to strap a canvas bag water cooler onto their vehicle. The bag wasn't completely water tight so the canvas stayed damp. After driving in the heat they would arrive with cool water, once again demonstrating the effectiveness of cooling by evaporation.

 

[SC Maintenance]

That's where the idea of sprinkling the roof comes in. Evaporation is a non mechanical way to cool anything, including a roof in the hot sun. And you could do that with minimal capital investment or running costs. [The OP was looking for low cost solutions.]

People used to strap a canvas bag water cooler onto their vehicle. The bag wasn't completely water tight so the canvas stayed damp. After driving in the heat they would arrive with cool water, once again demonstrating the effectiveness of cooling by evaporation.

Would for sure work at keeping the roof cool. But OP seemed to indicate at the location he is standing its pretty much ambient already - so it seems maybe he has enough airflow to move that heat out? If thats not true it would be easy enough to test. Put a thermometer on the bench and hose down the roof - see if the temp drops?

Now in a house - anything you can do to cool that attic helps cool the house, because there is not a open airflow from inside the house to the outside generally, and the ceiling is closer to the floor.

 

[50yr Street Mech]

You're gonna spend SOME money to achieve a temperature difference. Convert "cheap solution" into available capital that can be spent for us to help you better.

 

[ecotourist]

Would for sure work at keeping the roof cool. But OP seemed to indicate at the location he is standing its pretty much ambient already - so it seems maybe he has enough airflow to move that heat out? If thats not true it would be easy enough to test. Put a thermometer on the bench and hose down the roof - see if the temp drops?

Now in a house - anything you can do to cool that attic helps cool the house, because there is not a open airflow from inside the house to the outside generally, and the ceiling is closer to the floor.

You're right of course. Hosing down the roof with cool water would add an additional cooling effect, but at the cost of a lot of water My suggestion is to emphasize evaporation, which would involve much smaller amounts of water.

The physics of the situation is that through evaporation the highest energy water molecules would leave the surface, thereby reducing the average energy of the molecules left behind - thus cooling the roof. With evaporation you might actually cool the roof below the ambient temperature (or might not, depending on the solar load). Either way it would be cooler than before.

 

[4WD]

You're right of course. Hosing down the roof with cool water would add an additional cooling effect, but at the cost of a lot of water My suggestion is to emphasize evaporation, which would involve much smaller amounts of water.

The physics of the situation is that through evaporation the highest energy water molecules would leave the surface, thereby reducing the average energy of the molecules left behind - thus cooling the roof. With evaporation you might actually cool the roof below the ambient temperature (or might not, depending on the solar load). Either way it would be cooler than before.

Same with the mister fans. What I do with my patio swamp cooler is mist fresh/cool water on the media - not recirculating the warm water …
(Pump off - fan on low) … It’s not blowing water - just cooler air …
The excess water trickles into a flower bed with some nice smelling herbs
I know this is a different principle - but our humidity is high …

 

[SC Maintenance]

I think the only "cheap" solution is to cool himself not the space. So a fan blowing where he is working, or a portable AC unit blowing at the space he is working. I actually have a portable AC unit something like this I use for different things. He could point it towards what he is working on and put the flex exhaust hose far away and it probably would be the only realistic solution. Of course mine is 6000BTU and pulls about 1000W, which in CA would likely cost him 50 cents a hour I think.

 

[D60]

Yep, cool your hot body (so desired by hot neighbor girl) with one of those vests or even the bandanas you can wear around your neck, and keep airflow straight on you. IOW become the swamp cooler (creature?).

A misting fan is not a terrible idea, either.

These are your cheap options: fans and evaporation.

Insulate between a couple studs every week if you must. How do you eat an elephant? One bite at a time.

 

[JimPghPA]

Heatpump waterheaters remove humidity and heat (provide cooling) from where they are installed and provide hot watter for less than half the cost of electricity compared to resistive hot water heating.

The radiant barrier previously mentioned is also a great idea.

 

[GI_GRIFF]

My garage is 20ftx24ft. We put insulation on the roof when we reroofed it. No insulation in the walls.

It gets unbearably hot in there during the summer. A few years ago I put an evaporative cooler in a window which only pushed the cool air out the whirly bird on the roof without effecting the inside temp.

Anyone have any ideas I may not be aware of? Adding insulation to the walls would be a serious job and not something I'd want to do in the summer.

This time of year, this will work. Take off early on a Saturday morning say 8:00 AM, and cruise the neighborhood streets for yard sales. Look for used electric fans, buy a few and plug them in!

 

[AZjeff]

Heatpump waterheaters remove humidity and heat (provide cooling) from where they are installed and provide hot watter for less than half the cost of electricity compared to resistive hot water heating.

The radiant barrier previously mentioned is also a great idea.

Right now in Apple Valley the RH is 19% and could go under 10 in the afternoon when it goes to 105. Things are different in the west.

The temp in an uninsulated garage is going to be close to ambient all day and could be higher later on if closed up.

The cheapest cooling solution is a used $200-300 house size evap cooler and it may struggle. The trick is to get it as cool as possible in the morning and hope to stay ahead of the air temp and sun bake.

Paint the garage white. Cheap and every little bit helps.