Comparative environmental life cycle assessment of urban green spaces and design elements – A case study in Vienna

Urban green spaces are becoming increasingly important due to their multitude of ecosystem services. Until now, the focus of environmental impact assessment has been mainly on greenhouse gas emissions. Hence, this study aims to assess common green spaces in Vienna with the method of life cycle assessment for the impact categories climate change, fine particulate matter formation, marine eutrophication and terrestrial acidification over the whole life cycle. A utility lawn (UL), a meadow lawn (ML) and a perennial bed are compared with each other based on the functional unit (FU) of 1  m² covered area over 30 years. Further, combinations of UL and ML with each other and with two different pathway options are assessed in hypothetical park compositions. Results show that the UL as intensively maintained green space has higher environmental impacts compared to extensively maintained ones (ML, perennial bed); e.g., in the impact category climate change ML and perennial bed have an impact of 2.90 and 10.68  kg CO₂ eq./FU, respectively compared to UL with 54.59  kg CO₂ eq./FU. Overall, the maintenance phase is a hotspot in every assessed impact category. When increasing the size of UL this leads to a reduction of environmental impacts; e.g., a 2.5 times bigger area reduces the GWP by over 50 %. When combining UL and ML, the marine eutrophication potential can be reduced significantly due to less fertilizing and mowing. A combination of green space and pathways does not result in a large increase or a significant reduction in environmental impacts.