Life cycle assessment in buildings: State-of-the-art and simplified LCA methodology as a complement for building certification

The paper presents the state-of-the-art regarding the application of life cycle assessment (LCA) in the building sector, providing a list of existing tools, drivers and barriers, potential users and purposes of LCA studies in this sector. It also proposes a simplified LCA methodology and applies this to a case study focused on Spain. The thermal simulation tools considered in the Spanish building energy certification standards are analysed and complemented with a simplified LCA methodology for evaluating the impact of certain improvements to the building design. The simplified approach proposed allows global comparisons between the embodied energy and emissions of the building materials and the energy consumption and associated emissions at the use stage. The results reveal that embodied energy can represent more than 30% of the primary energy requirement during the life span of a single house of 222 m2 with a garage for one car. The contribution of the building materials decreases if the house does not include a parking area, since this increases the heated surface percentage. Usually the top cause of energy consumption in residential building is heating, but the second is the building materials, which can represent more than 60% of the heating consumption.