Secondary Glazing Systems (SGS) are window attachments with insulating high-performance glazing in anodized or painted aluminum frames with low-e coating on double-lite (IGU) glass. They are installed from the interior side without replacing the existing glass, window frames, or altering the exterior appearance of the building. They are considered when it is desired to save energy, reduce carbon footprint, and significantly increase occupant comfort thermally, visually, and acoustically in existing commercial buildings with existing clear single pane low-performance windows. This measure only addresses office buildings but the RTF is also developing savings estimates for additional business types.
The SGS measure is currently considered Planning by the RTF, as the simulation models are largely uncalibrated to real world data. The RTF has adopted a research strategy to address the remaining uncertainties in SGS energy savings.