Comparative Life Cycle Assessment of refurbishment alternatives for façade assemblies typically used in existing buildings in the Mediterranean region in Spain

Abstract

The building sector is a major contributor to the environmental impact in the European Union due to energy consumed, extraction of resources and greenhouse gas emissions. Particularly, the existing building stock represents a greater challenge than new constructions, since up to 85% of the buildings existing in 2050 have already been built. The extensive lifespan of buildings mean that construction assemblies remain standing for long periods of time, which accounts for most of the embodied environmental impact and affects its energy performance during the use stage. Also, because the façade surfaces generally cover most of the building envelope, they have strong potential to reduce existing buildings' environmental impacts and energy consumption, when undertaking major refurbishments. This paper aims to compare the environmental performance of different refurbishment alternatives for façade assemblies typically used in existing buildings in the Mediterranean region in Spain. For this purpose, a three-step methodology based on a life cycle approach was applied: (I) Identification of existing façade assemblies and their related refurbishment alternatives, (II) Bill of Materials, and (III) Environmental, cost and energetic impact of each façade and their refurbishment alternatives were analysed with the Life Cycle Assessment and Life Cycle Cost methodologies and U-values calculation, respectively. The results were used to draw conclusions to help construction sector practitioners, such as building designers and contractors, to make decisions during the design and construction stages in major renovation projects. They could also be used to select the optimum façade refurbishment alternatives, aiming at nearly zero-energy buildings.