This document specifies a method to measure the solar heat gain coefficient of complete windows and doors. This document applies to windows and doors with various types of glazing (glass or plastic; single or multiple glazing; with or without low emissivity coatings, and with spaces filled with air or other gases), with opaque panels, with various types of frames (wood, plastic, metallic with and without thermal barrier or any combination of materials), with various types of shading devices (blind, screen, film or any attachment with shading effects), with various types of active solar fenestration systems [building-integrated PV systems (BIPV) or building-integrated solar thermal collectors (BIST)]. This document does not include the following: shading effects of building elements (e.g. eaves, sleeve wall, etc.); heat transfer caused by air leakage between indoors and outdoors; ventilation of air spaces in double and coupled windows; thermal bridge effects at the rebate or joint between the window or door frame and the rest of the building envelope. This document does not apply to the following: non-vertical windows; curtain walls; industrial, commercial and garage doors.