Editing Passive solar building design (section)

===Special glazing systems and window coverings===

{{Main|Insulated glazing|Window covering}}

The effectiveness of direct [[solar gain]] systems is significantly enhanced by insulative (e.g. [[double glazing]]), spectrally selective glazing ([[low-emissivity|low-e]]), or movable window insulation (window quilts, bifold interior insulation shutters, shades, etc.).{{Sfn|Shurcliff|1980}}

Generally, Equator-facing windows should not employ glazing coatings that inhibit solar gain.

There is extensive use of super-insulated windows in the [[Germany|German]] [[Passive House]] standard. Selection of different spectrally selective window coating depends on the ratio of heating versus cooling [[degree day]]s for the design location.