Kan regn ersätta kommunalt vatten på campus? : En dimensionering och livscykelanalys av ett lokalt regninsamlingssystem vid Södra huset, Stockholms universitet

Sammanfattning

As climate change contributes to longer dry periods, more variable precipitation patternsand therefore an increased risk of water scarcity, the use of drinking water for purposesthat do not require potable quality has become increasingly relevant. The aim of thisthesis was to investigate whether rainwater harvesting can act as an environmentallysustainable alternative to municipal drinking water for irrigation at Södra huset,Stockholm University.The study was conducted as a case study in which a local rainwater harvesting systemwas dimensioned using the analytical Yield-After-Spillage (YAS) model together with aStorage-Reliability-Yield (SRY) analysis. The environmental performance of the systemwas then evaluated through life cycle assessment (LCA), focusing on climate impactand energy use. The system was then compared with the continued use of municipaldrinking water. Sensitivity analyses were performed to assess the influence of theassumed irrigation demand and the choice of municipal water as the reference system.The results show that, in the main scenario, rainwater harvesting is not climatemotivated compared with the reference case based on Stockholm Vatten och Avfall.Mainly because the climate impact of the system is dominated by materials. At thesame time, rainwater harvesting reduces both energy use and drinking water demand.The study therefore highlights a clear trade-off between climate impact, energy use andwater savings. The findings are also strongly dependent on the assumed irrigationdemand and local conditions, meaning that the conclusions are most robust on aqualitative level. The thesis demonstrates that rainwater harvesting should be assessedwithin a broader decision-making framework that also considers resilience, practicalfeasibility and other dimensions of sustainability