Anyone a/c their garage?

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davidcary

Well-known member
Joined
Mar 10, 2013
Messages
117
Location
Cary, NC
First - I realize this sounds crazy but....

I live in Raleigh - weather factor of 1.00 but it still gets hot (not Phoenix hot of course).

We have a 3 car attached garage with 3 west facing windows. The garage gets 100 in the summer pretty often - at least I think since I haven't measured it yet. I work some from home and am home most nights so the car spends a lot of time in there.

I have an efficient a/c unit with plenty of capacity (too much). I am going to an electric rate of $.05 off peak. I paid $350 combined for July,Aug, Sept for all electric at $.10 a kwh. The garage is pretty well sealed but not insulated (although 50% of the walls are against the conditioned house). The garage is roughly 20% of the volume of the house. I would predict $30 a year to run the a/c in the garage at night.

So isn't it worth $30 a year to protect my new $10k battery (obviously a guess on price)?

Seems incredibly wasteful from an energy standpoint. I can't tint or block the windows but they have blinds.
 
I have no plans to A/C my garage. I have thought about it. But the biggest issue is that the walls are not insulated. I could insulate the garage-door to an extent, but if the walls are not insulated then what is the point? I'm not going to rip out the drywall to accomplish it.

One of the issues I saw last Summer was that the garage would not cool off at night. The Leaf and Volt create heat when charging. And with both of them in the garage charging at night, I'd find the garage stayed in the upper 90's all night even though it dropped into the 70's or 80's outside. So what I began doing last year was leaving the garage door open until it was time to go to bed. By that point most of the time the cars were done charging anyway. Even then, I'd close the garage but stop it about 2-3 inches from the ground. That leaves a crack and the top and bottom for air to circulate.

What I HAVE considered doing is putting some sort of active ventilation in the garage. I just haven't figured out how. I have brick on the house and the only logical place to access outside would be through the garage door itself. While this would be an easy matter to mount some fans and cut out some holes. Some fans could blow in, while others blow out, circulating the air. The issue really is how to get electrical power to something that moves like the door. There are ways to achieve it, but I don't like any of them.
 
No, but I do have a fan in there now (pointed right under my Leaf) and it did seem to help in the worst part of the summer here last year. On 100+ degree days, it brought a 90+ garage down to 80+ by the time charging kicks in early in the morning; the "proof in the pudding" was it lowered 7TB (when I parked at night) to 6TB (at charge time).

Your question is a good one, but probably unnecessary for someone NOT in an extreme heat area who doesn't see a lot of 7TB readings. If I can get by in TX without garage A/C, I would think a lot of places can. Obviously, I only use the fan on those 7TB days.
 
If you're going to A/C the garage, you probably want to at least make sure it's minimally insulated.

Venting the garage is probably easiest - at least some passive venting perhaps with active venting.

I'd love to have a setup where a fan runs if the garage is say 5F warmer than outdoors (perhaps put a minimum temp on it, too - don't like walking into a too-cold garage!). I doubt it'd take much energy to keep the garage close to ambient with an efficient fan with a setup like that.

Let's see - my garage is about 22x22x15 or about 7260 CFM - hmm, going to need some beefy fans to vent that area quickly, maybe not quite so much if one expects that only the air near the ground needs to be cooled.
 
There were a couple of people who posted about doing this sort of thing. One installed a window-type swamp cooler. There's also been talk about improving venting and adding ventilation fans.

It goes without saying that you don't want to tie the garage into your central air system. Carbon Monoxide, anyone?
 
You might need a separate air conditioner to meet code. Would the venting be permitted with various fire wall protection required?
Also garage needs low vent to the outside... or is that just for the natural gas w/h or furnace?
 
All good thoughts.

Insulation is a non issue - I wouldn't try to keep the temp lower than outside - or at least not more than a few degrees lower than outside which would be no real temp gradient.

Code is a non issue although points well taken.

I was thinking just a supply vent so no intake in the garage but I suppose if you just had EVs it doesn't really matter. But either way, tying in ventilation has its issues.

I suppose I should start with active ventilation and see what I can get the temp down to. I'll probably try just exhausting out the top and leave the door open an inch or two.
 
It may be overkill, but I put two ceiling fans in my garage (not insulated). When it's hot I crack the door an inch or two and flip the fans on. They produce a noticeable draft and cool the garage off fairly quickly.
 
gaswalla said:
Isn't it ironic that LEAF owners are willing to spend extra time and money to protect the battery, but Nissan chose not to?

Apples and oranges: whatever Nissan does would have to apply to EVERY Leaf along with the associated cost (whether it's needed or not). Whatever individuals choose to do depends on individual requirements/needs; there will be those who choose extra care (and don't really need it) and those that don't do anything (and later regret it).
 
Where I live A/C is not necessary, but isn’t that what Thermal Battery Management is for? What do you do when the car is parked outside or at work?
 
For me, I'll park outside and accept the degradation. But it is all about limiting the time at temp. If my battery can charge at 80 degrees instead of 90 in the summer, it will be happier. Would it have been happier if I bought a Tesla - sure - but my pocketbook wouldn't be...

I am not crazy about Nissan's decision to not actively cool the battery but I bought it anyway. Since it seems like the colder temps the better, I just want to do what I can to keep things colder (within reason).
 
Our garage is fully insulated. Our strategy last year was to open up the main door in early morning and then keep it closed as much as possible during the day. This helped as long as we didn't take the LEAF out. But if you go out in 100F weather, the battery quickly comes up to that temperature, even if it had been down around 80F in the garage.

I would consider running a window A/C on those hottest of days, but I suspect that driving the LEAF in the hottest part of the day is its biggest enemy. It takes many hours for the battery to cool down unless it is driven in cool air to speed the process of cooling off.
 
My garage has a window. During summer I have a box fan to pull cool air in. It runs on a timer to catch lowest cost TOU 12a to 6a and lowest air temp. Air is expelled through the regular safety vent. I might reverse the flow this year and see if it works better. Window is higher than the vent.

Good luck to those that are in hot climates.
 
Have a 3 car garage fully insulated. Recent remodel freed a heat/ac vent. It now feeds the garage. Warm in winter, Cool in summer -Colorado can be extreme. :|
 
I used an old window A/C unit on a timer in my garage this Summer. It wasn't hard to keep the temp in there below 77F, despite a very Hot summer. I only ran the A/C at night, after peak demand.
 
Have a 3 car garage fully insulated. Recent remodel freed a heat/ac vent. It now feeds the garage. Warm in winter, Cool in summer -Colorado can be extreme. :|

Didn't bother with a permit, did you? I don't think you're allowed to put your garage on your central air system as it would be a conduit for car fumes to enter the house.
 
davewill said:
Have a 3 car garage fully insulated. Recent remodel freed a heat/ac vent. It now feeds the garage. Warm in winter, Cool in summer -Colorado can be extreme. :|

Didn't bother with a permit, did you? I don't think you're allowed to put your garage on your central air system as it would be a conduit for car fumes to enter the house.

I keep seeing this, but with a one-way flap on the outflow register in the garage, and no air return from the garage, that's a very unlikely scenario - especially if it's an EV in the garage.
 
LeftieBiker said:
I keep seeing this, but with a one-way flap on the outflow register in the garage, and no air return from the garage, that's a very unlikely scenario - especially if it's an EV in the garage.
Except that AC vents don't usually have one-way flaps, and the next owner (or your AirBnb tenant) might park a regular car in there. We'll just ignore the fact that without a return, you're depressurizing the house and making the system work harder. Anyway, I'm fairly confident it won't pass inspection.
 
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