I live in Montreal and I just moved from a building that had double sliding windows in each window frame (I assume a single pane each) to a building with single double-pane windows that look a lot newer. The heating bill for the new apartment is much larger and the soundproofing is non-existent, I have a volume of street noise that sounds like my windows are open at all times, I can hear two people talking on the other side of the street (I am on the second floor).

As per my limited experience, the double window technology (two single panes) seem to be a lot better than the newer windows in the new apartment. That's what my parents in Russia seem to have too and the second window was installed on the interior for the winter only and removed during summer.

I would like to do some research online, but I am not sure what to even call the double window set-up, nothing comes up. Any tips? What's your experience with this?

Edit: Interior Storm Windows seem to be the best term so far. The question remains - why is this considered an outdated technology? Again, from my limited experience it seems better to me in every way than any fancy new windows.

  • Can you post a picture?
    – mmathis
    Oct 21, 2016 at 16:00
  • 1
    Storm window? Pictures would definitely be helpful
    – Niall C.
    Oct 21, 2016 at 16:05
  • a picture of what? It's just a regular slider window, only there is two of them in one window frame, one on the inside, on on the outside. All older buildings in Montreal have them. To open a window, you have to slide open two panels, one on the inner window and one on the outer window.
    – Natalia
    Oct 21, 2016 at 16:06
  • SO SOMETHING LIKE THIS? where the inner pane is remove in the summer and replaced with a screen. I have not seen these for 40-50years in the US. Todays double and triple pane inert gas filled have replaced them. Oct 21, 2016 at 18:14
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    The term is double hung with 2 moving panels single hung with 1 moving panel. double hung can be ordered in 1,2 or 3 panes of glass with gas filled centers that do block sunlight and are both sound reducing and energy efficient.
    – Ed Beal
    Oct 21, 2016 at 19:09

2 Answers 2


Sounds like you're talking about "triple-track storm windows", which usually has 3 panels, 2 with glass, one with a screen; in the summer you slide the bottom glass panel up, and screen down; in the winter you slide it down. They were commonly retrofitted to older houses that had no storm windows.

Newer windows (the windows themselves, not the storm windows) usually have two glass panels with a vacuum or gas in between, eliminating the need for bolted on storm windows. The newer windows, besides being more energy efficient, also can block UV rays that damage curtains and furniture.

The reality is there's a lot of cheaply made windows out there that look modern, but transmit sound like a hollow steel drum; and properly maintained triple tracks can be almost as energy efficient.

  • 1
    And if building codes do not call for it, those cheaper windows get installed. Oct 21, 2016 at 18:17
  • yes, thank you, that's exactly it. Although in all apartments I lived it, the windows slid open horizontally.
    – Natalia
    Nov 15, 2016 at 16:57

Sliding windows are never very energy efficient AND retrofit sliders are the worst.

Sliders have to fit “loose” in their frames in order to allow them to slide...as opposed to awning, hopper, casement, etc., which can fit tight and be “cinched down” with a clasp.

In addition, old windows do not have a “thermal break” frame. Energy can be transmitted through the frame just as it can be transmitted through a single pane window.

Adding storm windows to old windows seems like it would save a lot of energy, but its performance is based on 1) size and fit of storm window to existing window frame (and multiple windows will vary slightly in size), 2) how square the original window was installed (and the existing windows could be “tweaked” out of shape making the storm window not fit perfectly), 3) existing window frame material ( which could have joints, not fit properly at edges, etc.), 4) perimeter flange (If Any) is not sealed to the building.

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