davidcary
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Anyone a/c their garage?

Mon Mar 18, 2013 2:58 am

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.

adric22
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Re: Anyone a/c their garage?

Mon Mar 18, 2013 6:05 am

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.
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Stanton
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Re: Anyone a/c their garage?

Mon Mar 18, 2013 7:25 am

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.
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drees
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Re: Anyone a/c their garage?

Mon Mar 18, 2013 8:14 am

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.
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davewill
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Re: Anyone a/c their garage?

Mon Mar 18, 2013 10:03 am

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?
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smkettner
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Re: Anyone a/c their garage?

Mon Mar 18, 2013 11:05 am

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?
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davidcary
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Re: Anyone a/c their garage?

Mon Mar 18, 2013 11:49 am

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.

gsleaf
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Re: Anyone a/c their garage?

Mon Mar 18, 2013 12:41 pm

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
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Re: Anyone a/c their garage?

Mon Mar 18, 2013 12:52 pm

Isn't it ironic that LEAF owners are willing to spend extra time and money to protect the battery, but Nissan chose not to?

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Stanton
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Re: Anyone a/c their garage?

Mon Mar 18, 2013 1:27 pm

gaswalla wrote: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).
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