Energy specification
October 2026
An insulated glass unit combines panes with a sealed space between them. Coatings, spacers and gas fills can affect its thermal properties, but glass-only figures do not describe the performance of an entire window.
Whole-window U-factor describes heat transfer; a lower figure indicates less heat transfer under the rating conditions. Solar heat gain coefficient describes the fraction of solar heat transmitted. The appropriate balance depends on orientation and the building.
Compare the complete window, not just the pane.
Compare published figures for the exact product and configuration proposed. Frame construction, thermal breaks where applicable and air-infiltration data belong alongside the glazing discussion.
Installation details influence the finished result. Perimeter sealing, flashing and drainage should be specified, while indoor humidity and ventilation remain part of the condensation discussion. No universal energy saving or condensation outcome is promised.
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