Trying to figure out the best way to cool an attached garage. The garage door is insulated and has weather stripping on the outside. There are no windows and the exterior is brick. We live in a humid climate, south Texas, humidity 80% in the morning and 60% at night. Newer construction, 2015.

Researched mini-splits but it's just too expensive, approx $4-5K.

Looking at portable units. Reading a lot of conflicting info on one or two hose systems and the best way to vent. There aren't many options when it comes to venting, there are no windows and the wife doesn't want holes cut through the brick. Can I vent either a one hose or two hose portable system into the attic? The attic is passively cooled.


  • Have you considered a through-the-wall A/C? (they're like window units, but mount in a wall sleeve instead of a window) Jul 21, 2020 at 0:19
  • What size system do you need? There are mini-splits in the $1200 range, if you're not talking about a very big one. Here's one example: homedepot.com/p/…
    – Nate S.
    Jul 21, 2020 at 0:20
  • Check out mrcool for a 100 % diy option on mini splits , not enough Information to provide a real answer. VTC
    – Ed Beal
    Jul 21, 2020 at 0:35
  • 1
    What color is the roof? Jul 21, 2020 at 1:50

2 Answers 2


I had a grey tin shed that was getting very hot in the summer. The cheapest and quickest fix was to paint the sides and roof side that faced the sunlight, with some random white paint I had laying about. It wasn't a quality job, but in my case it was around the back and not visible.

Decreasing the insolation is a good start, is silent, and needs no ongoing costs like power.

Then you can start exploring more costly solutions like active cooling.

  • Insulation works in both directions - think of a vacuum flask...
    – Solar Mike
    Jul 21, 2020 at 6:06
  • 2
    @SolarMike I didn't typo - "insolation" is heat from the sun. Limiting that with light colours helps a lot and is a cheap start
    – Criggie
    Jul 21, 2020 at 7:50
  • 3
    There are nature's automatic shading systems that work very well, trees which allow winter sunshine but not summer, then climbing plants that do the same... very cheap as they tend to grow for free...
    – Solar Mike
    Jul 21, 2020 at 7:52
  • 2
    Climbing plants have the added bonus of eventually destroying the things they're climbing! Oh, wait, that's not quite so good... :(
    – FreeMan
    Jul 21, 2020 at 12:45

How cool do you want a garage ? A small attic fan would help but you need some place for air to enter. A portable unit can blow hot air into the attic, but you still must have an intake through a wall. I have a cooled room in my detached garage ; I put the room AC through the interior wall into the garage . It takes air from the garage and blows hot air into the attic (I built a plenum around it). It cools one room fine for $ 100.

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