Secondary glazing systems (SGS) offer building owners the opportunity to improve existing window performance, increase tenant value and decrease operating expenses—all with virtually no disruption to ongoing building operations. Historically, replacing windows in leased or otherwise occupied buildings was disruptive to tenants, especially in the case of tall buildings where access to the exterior is difficult. SGS, however, is easily installed in 20 to 30 minutes per window, offering a non-disruptive alternative to conventional full window and frame replacement. By adding a new single or double-pane insulated glazing unit (IGU) to older single-pane or non-low-e glass, SGS improves the window’s thermal performance with relative ease. This simple solution comes with a host of benefits including improved thermal comfort, better acoustics, and energy improvements, while bringing leaking, thermally inefficient single-pane windows up to the standards of current Class-A office buildings.