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Community and Q&A

Energy options for sliding glass door

ajonesaz | Posted in Energy Efficiency and Durability on

So I am in the Phoenix Area, so heat gain is my most important factor. I am considering 2 Milgard 12’x8′ sliding glass doors

Door A: LowEMax, uf: .33, SHGC .22, VT .50
Door B: LowE, built in blinds, uf.35, SHGC .27, VT .50

I am thinking Door B specs are glass only with the blinds open. Since the blinds are sealed in the glass, it can’t do the extra coating inside because blinds would scrape it off. Since I work 9 to 5 weekdays I can leave the blinds closed and room dark during the hottest part of the day.

So to my real question, which is more energy efficient? Door B with blinds closed 80% of the time or Door A with no blinds.

No one that sales these doors has apparently been asked if the values are calculated with blinds open or closed.  How much can .05 SHGC increase my cooling cost? Is blocking the sun with blinds better than the extra coatings?

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  1. BrianPontolilo | | #1

    Hi Ajonesaz.

    This is a great question and I'd love to know the answer. I've reached out to my colleagues to see if any of them have a good inside contact at Milgard. If I can get in touch with someone there, I'll see what I can find out. In the meantime, I'm giving your post a bump in case another GBA user knows the answer.

  2. AndrisSkulte | | #2

    You can model the room with Manual J software like CoolCalc with the shades open and closed, and see the BTU value difference, then extrapolate that to your cooling system efficiency...

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