This part of ISO 10077 specifies methods for the calculation of the thermal transmittance of windows and pedestrian doors consisting of glazed and/or or opaque panels fitted in a frame, with and without shutters.

This part of ISO 10077 allows for

• different 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);

• opaque panels within the window or door;

• various types of frames (wood, plastic, metallic with and without thermal barrier, metallic with pinpoint metallic connections or any combination of materials);

• where appropriate, the additional thermal resistance introduced by different types of closed shutter, depending on their air permeability.

The thermal transmittance of roof windows and other projecting windows can be calculated according to this part of ISO 10077, provided that the thermal transmittance of their frame sections is determined by measurement or by numerical calculation.

Default values for glazing, frames and shutters are given in the informative annexes. Thermal bridge effects at the rebate or joint between the window or door frame and the rest of the building envelope are excluded from the calculation.

The calculation does not include

• effects of solar radiation,

• heat transfer caused by air leakage,

• calculation of condensation,

• ventilation of air spaces in double and coupled windows,

• surrounding parts of an oriel window.

The part of ISO 10077 does not apply to

• curtain walls and other structural glazing,

• industrial, commercial and garage doors.