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Window question

EWmDE2AA3b | Posted in Energy Efficiency and Durability on

We are considering the following two options most seriously for the east, west and north sides of our straw bale home:
1. Northerm quad pane PVC with low E x 2 coats plus argon gas or
2. Cascadia or Clarity fiberglass frames, triple pane plus low E x2 and argon.

We’ve been researching for quite a long time and have seen the fiberglass windows and a sample of the pvc is being mailed to us from the Yukon. Does better glass outweigh the frame flaws? Do you agree that fiberglass is a better frame choice?The price quote from Northerm is substantially less. We have to try to decide soon which company to buy from. Any help will be appreciated.
Vicky

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Replies

  1. GBA Editor
    Martin Holladay | | #1

    Vicky,
    Q. "Does better glass outweigh the frame flaws?"

    A. The frame material and the glazing are two separate issues. You can have excellent frame performance and lousy glazing, or vice-versa. Apples and oranges.

    Q. "Do you agree that fiberglass is a better frame choice?"

    A. Yes.

  2. EWmDE2AA3b | | #2

    Which would you get for your home? Would you choose the best glass or the best frame? What if the vinyl frame is foam filled?

  3. GBA Editor
    Martin Holladay | | #3

    Vicky,
    You didn't provide U-factor or SHGC information. You didn't tell us where you live. So it's hard to evaluate these options.

    Are the quad pane units true quad panes (four layers of glass) or two layers of glass with two suspended plastic films?

  4. EWmDE2AA3b | | #4

    We live in east central Alberta, Canada. True Quad panes with 4 layers of glass picure window is: U factor imperial .13, window R- value 7.69, SHGC .24; casement window is: U factor imperial .16, window R value 6.25, SHGC .18 These are just for three sides of the house, not south where we really want the solar heat gain. Northerm also makes a triple glaze window: U factor imperial .20, R value 5.00 and SHGC .34 but so far one of us in the family prefers fiberglass frames and one of us leans towards quad pane. Looking at triple glaze pvc might just confuse us even more!

  5. GBA Editor
    Martin Holladay | | #5

    Vicky,
    It's not clear to me that the quad-pane unit is "better." There are trade-offs with any choice. Although quad pane windows have a low U-factor, which is good, I'd be worried about the VT. If the SHGC is that low (0.18), then there is a good chance that the window has a low VT, meaning that the window will make everything look gray.

    I would probably prefer to somewhat higher (worse) U-factor in exchange for a higher (better) VT.

  6. EWmDE2AA3b | | #6

    All the windows are under an overhang of 3-4 ft. Our original thinking was to have a dark colour for the exterior window frames, so we could draw as much sun as possible to the area, but is this best or would a lighter colour of frame be better?

  7. GBA Editor
    Martin Holladay | | #7

    Vicky,
    I don't see why a darker window frame would significantly affect the performance of the glazing or the view through the window.

    Dark colors raise the temperature of the frame. In the case of vinyl-framed windows, dark colors should definitely be avoided, since hot vinyl gets soft. Dark-colored vinyl experiences significant expansion compared to white vinyl.

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