2 or 3 Panes?

If 2 Panes of Glass are Good, Aren’t 3 Panes Better?

Yes and no. Let’s talk about the theory of a window. In a cold climate a single pane window will be close in temperature to the outdoor temperature. This means drafts, and energy loss. When you add a second piece of glass, the “dead air space” between them acts as an insulator.

If the outdoor temperature is 35 degrees, the inside of a single pane window might be 55 degrees. If you add an additional piece of glass, the temperature of the innermost glass might be 68 degrees. If you add still another piece of glass the interior surface will be very close to the indoor temperature.


This is the ultimate if price is no object, and utility not a consideration. The drawback, in addition to cost is weight. If you open and close the window the added weight strains the window hardware, not to mention the person involved. Some inventive person devised a system that replaced the middle piece of glass with a flexible Mylar sheet. This had similar energy saving properties without the weight. The only negative to this system is the expansion and contraction of the Mylar. This has the effect of distorting the view when one looks through the window.

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