Window glass?

Discussion in 'HVAC Heating & Cooling' started by mar3232, Mar 8, 2012.

  1. mar3232

    mar3232 Member

    Messages:
    108
    Location:
    Indiana
    Just thought I'd ask in case anyone knew -- a bit off topic.

    I have a large south facing window that I like to keep open (no curtains etc), which is great for winter but not such a good thing in summertime.

    Is there any type of storm window or film or "something" that I could add to this window to help repel the heat in summer? Of course, inside blinds but I do want to keep the window open for viewing at all times.

    Wonder if the make a roll down interior blind (that you could see through) I could use? Doesn't have to be clear -- tinted would be ok.

    Or maybe I could build something out of a lexan sheet or a plastic that I could mount inside (interior) the window frame and remove every winter. ?
  2. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    The only real answer to this is to put in double pane glass with top of the line low-e specs, possibly a tint, etc.
  3. Dana

    Dana In the trades

    Messages:
    2,915
    Location:
    01609
    Exterior sun shades work pretty well for killing the solar gain without fully obstructing the view but it does add visual noise to the view.

    [​IMG]

    If your windows are sealed glass double-panes you DON'T want an interior storm window of any type (low-E or otherwise) or a low-E window film in summer, or you'll overheat the glass and risk blowing the seal, resulting in the fogged-window look much of the year.

    If you can find the right vendor that can handle oversized windows there are some VERY good hard-coat low-E exterior storm window glazings out there now, that would blow away any window film or Lexan solution on performance, and you can probably collect some energy-efficiency kick back on it. I don't know if these guys are close to you or if they have the right stuff, but they've at least heard of the right stuff. I have no experience with these folks either, but it looks like you can order custom good online. Having the low-E goods on the exterior traps far less heat at the sealed window, so you're far less likely to damage a sealed window with exterior low-E storms. With uncoated exterior storms there is still some risk, but with low-E storms, not so much.

    In Indiana you still want to take advantage of the wintertime solar gain, and if your window is single pane you might want to pick an emissivity level that isn't too severe so that the resulting solar gain factor is still reasonable in winter, but adequately rejecting in summer and leave it up all year. This is easier to do on south facing windows than east or west, since the summertime sun is pretty high during the mid-day, and you reap the benefit of higher external reflection, whereas the rising and setting sun is low any time of year, with higher penetrating gains. VERY low-E coatings can also cut too deeply into daylighting, making the room feel pretty dim in anything but full sun, so going for something middle of the road probably makes more sense.
    Last edited: Mar 8, 2012
  4. mar3232

    mar3232 Member

    Messages:
    108
    Location:
    Indiana
    Thanks Dana -- very informative -- printing it out for reference.
  5. Dana

    Dana In the trades

    Messages:
    2,915
    Location:
    01609
    It looks like both Larson and Bonded Insulated Products sell low-E storms in IN, with special pricing for volume buys (20+) under a DOE program. Because Larson distributes through box-stores you can apparently get the DOE volume pricing at quantity 6 or more(?) if you click on their voucher link and print it out before heading out to the participating store.


    http://www.windowsvolumepurchase.org/search.aspx?wt=9&ct=1&sc=1&sr=16


    Either way, both companies can accommodate retrofitting picture windows.

    If you have other windows that could use tightening or higher performance, it's worth taking stock of what's there. If there are double-hungs or sliders that you literally never open, installing a tight fixed pane low-E storm would improve performance better than a triple-track storm since air leakage would drop to near-zero.
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