A clarification that comes in a context of strengthened thermal requirements: AGC Glass Europe, a subsidiary of Japanese group AGC, has released a reference document detailing the technical functions of flat glass in architectural, automotive and industrial applications. This editorial positioning aims to reinforce the recognition of glass as a key material for the energy performance of the building envelope, particularly within the framework of European regulations on energy renovation.
The AGC Glass reference framework highlights four main functions of glass in façades: light transmission, solar control, thermal insulation and safety. For each function, the manufacturer specifies the relevant normative values. Light transmission is characterized by the light transmission factor TL (according to EN 410), which directly influences artificial lighting consumption in tertiary buildings. Solar control, expressed by the solar factor g, determines the share of solar energy transmitted through the glazing and impacts cooling requirements. For low-emissivity coated glazing, g values can drop to 0.28, thus reducing up to 72% of solar energy input according to the manufacturer's data.
In terms of thermal insulation, AGC recalls that performance is measured by the Ug coefficient, expressed in W/(m².K) in accordance with EN 673 standard. Triple glazing with argon filling and low-emissivity coatings can achieve Ug values of 0.5 W/(m².K), a performance that becomes the reference for projects subject to Passivhaus or KfW-Effizienzhaus 40 criteria. This technical evolution is part of the decarbonization dynamic of the European building stock, where the glazed envelope often represents the thermal weak point of façades.
The technical document also discusses safety functions, distinguishing tempered ESG glass, whose mechanical resistance is multiplied by five compared to annealed glass, and laminated VSG glass, which maintains its integrity in case of breakage thanks to a PVB or ionomer membrane. For applications in exposed façades, EN 12600 standard classifies glazing according to its impact behavior.
In terms of sustainability, AGC Glass emphasizes glass's contribution to reducing the carbon footprint of buildings through optimization of passive solar gains and reduction of energy consumption during the operational phase. The manufacturer mentions the availability of environmental product declarations (EPD) for its main ranges, a tool that has become strategic in the context of DGNB or BREEAM certifications. However, the publication does not provide quantified data on the rate of recycled glass integrated into production, nor on CO₂ emissions per m² of manufactured glazing, indicators that have nevertheless become decisive for prescribers in a context of rising circular building.
This editorial initiative by AGC Glass comes as the European insulating glazing market is undergoing restructuring, driven by energy renovation programs but hampered by volatility in production energy costs. Positioning glass as a lever for thermal performance and visual comfort could strengthen its place in tertiary building rehabilitation strategies, where glazed façades represent up to 60% of the envelope surface in certain office typologies.
