A Methodology for Accurate Embodied‑Carbon Assessment of Insulating Glass Units using EPD Data

Abstract

Architectural glass accounts for approximately 26 % to 60 % of the total façade embodied carbon, depending on the façade typology and glazing configuration. Within the European Union the EN 15804 constitutes the core standard for the assessment of environmental impacts of construction products. The standard structures the data in a framework of four life cycle stages (A to D) and further separate these into seventeen modules. The Environmental Product Declarations (EPD’s) are voluntary product labelling systems structured according to the modular framework defined in EN 15804. Using Global Warming Potential (GWP) values extracted directly from product specific glass EPD’s the embodied carbon of any glass unit configuration can be calculated. Building upon the CWCT approach for embodied carbon assessment of insulating glass units (IGU’s), this paper introduces new expressions and a structured calculation workflow to support consistent use of EPD data in IGU embodied carbon calculations. The method also introduces revised embodied carbon factors for the IGU assembly process which are derived from a comparative assessment of available IGU EPD data. As a result, the proposed method generates EN 15804 compliant results and is implemented in an interactive spreadsheet, referred to as the Glass Embodied Carbon Calculator (Glass ECC) which provides a systematic framework for embodied carbon assessment across different IGU configurations.