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Community and Q&A

Ways to cool in Hawaii

Lavender83 | Posted in General Questions on

Hello, I’m in a zone-1 area, specifically, the Leeward side (hot dry!) of Oahu. My house was built in the 80’s, has minimal to no insulation and none in the attic, and only has window-unit AC (mounted in the wall). I prefer not to use the AC when at all possible, but as the summer comes on, it ends up getting hotter inside than outside with a breeze despite having the windows and garage open.

Because there is no attic insulation, and the attic does get exceptionally hot, would an attic fan be of benefit in this instance? I currently can feel warmth radiating from ceiling fixtures (turned off), so I think there is some fair amount of transference of air from attic to house.

I have no concern of it getting ‘too cold’ in the winter months, and generally nights are pleasant.

I would like to explore options to keep my cool in the summer, without using the window units, or spending lots of time and money getting fiberglass all over my house by insulating the ceiling.

Thank you for your advice!

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  1. GBA Editor
    Martin Holladay | | #1

    Your house sounds like a good candidate for a whole-house fan. Here is a link to an article with more information: Fans in the Attic: Do They Help or Do They Hurt?

  2. Dana1 | | #2

    The combination of a mop-on cool roof finish on the exterior, a low-E paint on the interior side of the roof decking, and an aluminized fabric type radiant barrier in combination would likely drop your peak attic temps by more than 20F, would use NO power (is electricity in HI expensive enough yet? :-) ) and would make no noise.

    For painted-on cool roof materials search the for verified perfomance product at the Cool Roof Rating Council website:

    Don't get sucked into ceramic bead paint so other hype for the decking underside. There are a few tested paints with some (if marginal) merit:

    Don't get sucked into aluminized bubblepack either. Aluminized fabric types are cheaper and more rugged. The additional performance of the bubble pack types isn't worth the upcharge. There are literally dozens of aluminized fabric radiant barrier vendors.

    Having the low-E paint facing the r.b. across an air gap enhances the performance of both. Having the radiant barrier facing the attic floor across the air gap provides some performance too. But a high SRI low-E roof would be what's doing the heavy lifting.

    Shading the roof with a solar array also lowers the temperature of the attic, which is probably a better investment than the cool-roof coating:

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