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Best source for high solar heat gain windows?

Rich Cowen | Posted in Energy Efficiency and Durability on

Hi, I would like to replace a few of my downstairs windows on the south side of the home to allow the sun to actually heat the interior space.

Those windows are typical low-e glass that shuts out the sun as well.

When I first investigated this issue around six years ago I found that most of the standard window brands did not offer this kind of glass as a “standard” option.

What brands do offer it without charging you 2x or 3x the price of a conventional “low-e” window?

From another post I saw mention of “Cardinal LoE-180 glass with SHGC=.69, U=26”. I suppose that I could live with anything in the range of 0.5 to 0.7 which is much better than the windows we have now.

Thanks for your help,


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  1. John Ranson | | #1

    I can't speak to their high SHGC glazing, but I found Inline Fiberglass pricing to be quite reasonable for high VT triple pane casements. They have a couple casements with fairly promising whole window specs (with argon, not krypton, to control cost):

    Glazing: 3mm Clear - Arg.- 3mm En Ad. [S3] - Arg.- 3mm En Ad. [S5]| ss
    U: 0.19
    SHGC: 0.45
    VT: 0.45

    3mm Clear - Arg.- 3mm 180 [S3] - Arg.- 3mm 180 [S5]| ss
    U: 0.17
    SHGC: 0.4
    VT: 0.48

    For pricing reference, this is what I got quoted about a year ago:

    $450 for a 3' x 5' casement ($30 / square foot)

    3 mm 272 [S2] - Arg - 3 mm Clear - Arg - 3 mm 180 [S5]
    U: 0.18
    SHGC: 0.3
    VT: 0.43

    Now, I have to ask: Are you sure you want that much SHGC? It would be awkward if you had to open the window in those rooms while heat was running in the rest of the house because the thermal gain was too high. I would recommend running a per-room manual J, if you haven't already.

  2. GBA Editor
    Martin Holladay | | #2

    All of the Canadian manufacturers of fiberglass-framed windows (Accurate Dorwin, Duxton Windows, Fibertec, Inline Fiberglass) should be able to supply high-solar-gain glazing.

    In the U.S., consider Pella Windows. Pella offers the NaturalSun option, which is a high-solar-gain glazing.

    For more information, see these two articles:

    High-Solar-Gain Glazing

    All About Glazing Options

  3. Brad | | #3

    In addition to those already mentioned, Milgard and Anderson. SHGC of .69 is for the glass only, a whole window value which will be lower.

  4. Rich Cowen | | #4

    Thanks. I am close to Boston so if anyone else is replying we can do some comparisons.

    The sizes of window I am taking about are a small casement window, around 24" x 36", and one larger double hung window (could be upgraded to a picture window).

    to John: The amount of light coming into the south side of the house is extremely low and needs to be increased so I am not really worried about having a huge A/C load. We never turn the AC on, I mean the last 2 years our window A/C was on less than 6 hours the whole summer. The trees shut out the sunlight after 2pm so we are just looking for some morning light. If we do make those windows much bigger we would be likely to close up one or two windows elsewhere on the 1st floor to keep a bit more of the heat in, in the winter.

  5. Rich Cowen | | #5

    It turns out that home depot sells Anderson and when I asked this question they showed me the chart of Andersen options for glazing. One of them is "Passivesun" which sounds just like what I need. If anyone has tried it let me know... On special order the cost was probably 8 to 10% higher for a window with that type of glass.

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