DIN EN 673:2011-04

This European Standard has been prepared by Technical Committee CEN/TC 129 "Glass in building", the secretariat of which is held by NBN. The responsible German committee is Working Committee NA 005-09-91 AA "Prüfung von Beschichtungen auf Glas" ("Tests for coatings on glass").This European Standard contains a calculation method to determine the thermal transmittance of glazing with flat and parallel surfaces. It applies to uncoated glass (including glass with structured surfaces, for instance patterned glass), coated glass and materials not transparent in the far infrared which is the case for soda lime glass products, borosilicate glass and glass ceramic. It applies also to multiple glazing comprising such glasses and/or materials. It does not apply to multiple glazing which include in the gas space sheets or foils that are far infrared transparent. The procedure specified in this European Standard determines the U value (thermal transmittance) in the central area of a glazing. The U value for the glazing components calculated in accordance with the standard shall be used for the calculation of the overall U value of windows, doors and other closures. In addition, U values are calculated using the same procedure for other purposes, in particular for predicting: - heat loss through glazing; - conduction heat gains in summer; - condensation on glazing surfaces; - the effect of the absorbed solar radiation in determining the solar factor. The following amendments have been made with respect to DIN EN 673:2003 - the former normative Annex A relating to the determination of the emissivity has been deleted, instead, reference is now made to EN 12898, "Glass in building - Determination of the emissivity" and - the former normative Annex B has been revised, in particular the example of iteration for a triple glazing, and is now, as Annex A, the sole annex in the standard. The most important amendment is adaptation of the internal and external heat transfer coefficients in order to avoid any ambiguities.