Dual glass pane windows...

[Externet]

As solar radiation crosses a single glass window, its warming of the room is kept as the heat has 'difficulty' in exiting again trough the glass towards the exterior.

In a dual pane window, after passing the external glass, there is little sun radiation to further cross the internal glass pane, warming the window.  Does it mean that a room with two glass pane window will allow less solar penetration to warm a room than a single glass window ?  (but will insulate better against internally generated heating system losses ? )

[StringJunky]

59 minutes ago, Externet said:

As solar radiation crosses a single glass window, its warming of the room is kept as the heat has 'difficulty' in exiting again trough the glass towards the exterior.

In a dual pane window, after passing the external glass, there is little sun radiation to further cross the internal glass pane, warming the window.  Does it mean that a room with two glass pane window will allow less solar penetration to warm a room than a single glass window ?  (but will insulate better against internally generated heating system losses ? )

Yes. Dual panes will absorb more heat-producing UVB, UVC, Thermal IR and Far IR; Near IR and UVA passes through, which lie adjacent either side of the visible spectrum. Two panes basically filter out more rays that would otherwise warm the room.

Edited December 8, 2018 by StringJunky

[MigL]

Two panes with a vacuum or gas filler, is a much better insulator than a single pane of much larger thickness.

Very little of the visible or near-visible radiation is attenuated, but thermal conduction is greatly reduced.
All windows in Canada are dual pane ( outside temp is -5 deg this evening in one of the southernmost parts of Canada ).

Edited December 8, 2018 by MigL

[StringJunky]

4 minutes ago, MigL said:

Two panes with a vacuum or gas filler, is a much better insulator than a single pane of much larger thickness.

He's on about the effect of two panes on light coming in.

[MigL]

Thanks Stringy, my mistake...

Glass is not totally opaque to infrared, but depends on the wavelength.
Near infrared ( close to long wavelength visible ) easily passes through glass.
Far infrared is absorbed and emitted by the glass ( at room temperature ).

This is a similar effect to greenhouse gases.
Visible and near visible light will pass through, no problem; but when absorbed and re-emitted at the much lower characteristic temperature of the room, will have a harder time escaping back out.
IE heat comes in ( unless you add other properties to the glass, such as tint ), but is prevented from escaping.
Two panes make little difference to the above, although I have read that much of the absorption is a 'surface' effect, increasing the surfaces to be crossed, would then, increase absorption.