Life Cycle Analysis of Vertical Building Extensions-Environmental Impacts of Different Material Selection

Abstract

Adding storeys to existing buildings plays a large role in sustainable urban densification and helps to decrease the growing demand for urban city housings. Vertical building extensions create living space without the need for further land use, by extending existing buildings vertically by one or more storeys. Research points to the possibility of creating 1.1 million homes through storey additions in German metropolitan areas. A common method for investigating environmental impacts of a building is a life cycle assessment (LCA). Because of vertical building extensions being a relatively new concept, research is lacking, especially for LCAs. Therefore, this study describes frameworks and rules for LCAs of vertical building extensions. Moreover, environmental impacts of different material selection within storey additions are investigated. For this, a realised storey addition is analysed and main construction materials of the exterior wall and roof are replaced. The environmental impacts of material selection are then compared using the impact category global warming potential. Results show that the choice of material has a large influence on LCA results. In this case, the wood construction has the lowest greenhouse gas emissions and amounts to approximately 180 kg CO2 eq/m2. The highest greenhouse gas emissions are emitted by a steel construction with approximately 230 kg CO2 eq/m2.