Punktlandung – Ermittlung der technischen Werte von bedrucktem und beschichtetem Glas

Spot landing: Determining the light and solar properties of fritted and coated glass. The use of ceramic fritted architectural glazing is becoming increasingly popular. Fritted glass, which is also known as enamelled glass, is defined as glass with a surface covering of glass frit that is applied by a printing method and fused to the glass substrate at elevated temperatures. Functional thin-film coatings on glass have been used in standard glazing units for many years to improve thermal insulation or for solar control. Specification of light and solar properties for these standard glazing types is well-defined and can be calculated on the basis of the algorithms specified in EN 410 [1] or ISO 9050 [2]. This is not the case for glazing units that incorporate fritted glass. The paper initially describes the different printing options for fritted glass and the fundamental principles of functional thin-film coatings. When glass surfaces are covered with glass frit, it is essential to note that the light-scattering coatings transmit and reflect incident radiation not only directly but also diffusely. The same applies when functional thin-film coatings are combined with frit coatings. Suitable measurement methods to collect the scattered radiation, measured transmittance and reflectance spectra, and the calculation of light and solar properties on the basis of the standards mentioned above are presented. At the same time, the limits of these standards and the need for their extension are demonstrated. © Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin.