BiH standard BAS EN ISO 10077-1:2025, Thermal performance of windows, doors and shutters – Calculation of thermal transmittance – Part 1: General, has been published.

The fourth edition of BAS EN ISO 10077-1:2025 has been prepared in a bilingual version, in Bosnian and English.

The original text of this European standard was prepared by Technical Committee CEN/TC 89, Thermal performance of buildings and building components, witch secretariat is held by SIS, in collaboration with Technical Committee ISO/TC 163, Thermal performance and energy use in the built environment.

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

The standard allows for the following:

-        different types of glazing (glass or plastic; single or multiple glazing; with or without low-emissivity coatings, and 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), and

-        where appropriate, the additional thermal resistance introduced by different types of closed shutter or external blinds, depending on their permeability.

The thermal transmittance of roof windows and other projecting windows can also be calculated using this standard, provided that the thermal transmittance of their frame sections is determined by measurement or numerical calculation.
Default values for glazing, frames and shutters are given in the 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 (see standards under M2-8),

-        heat transfer caused by air leakage (see standards under M2-6),

-        calculation of condensation,

-        ventilation of air spaces in double and coupled windows, and

-        surrounding parts of an oriel window.

The standard does not apply to:

-        curtain walls and other structural glazing (see other standards under M2-5), and

-        industrial, commercial and garage doors.

BAS EN ISO 10077-1:2025 was prepared by Technical Committee BAS/TC 36, Architectural constructions, technology and construction management, and building physics of the Institute for Standardization of Bosnia and Herzegovina.