This is very interesting. A design firm, VetroVentilato(r), is working on a system to use the air space inside multi-pane windows as an opportunity to heat or cool a room.

Basically, the space between the panes heats air from sunlight and is directed into a room in winter. In summer, air is circulated through the panes and ultimately out of the building in order to exhaust the hot air and cool the windows themselves reducing their radiant heat.

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