October 8, 2025Open Access

Evaluating the Life Cycle Assessment of Rain Gardens and Green Walls for a Sustainable Environment

AAAbdul Wahed AhmadiIstanbul University NBNi̇lgün BalkayaIstanbul University-Cerrahpaşa KVKarina VinkUniversity of Twente

Key Points

Rain gardens perform better in operational-phase impacts, reducing carbon emissions annually, while green walls excel in construction efficiency.
The life cycle assessment utilized ISO 14040/14044 standards across 25 studies, focusing on key environmental impact metrics like GWP and resource consumption.
Green walls show lower construction-phase impacts attributed to modular design, while rain gardens support superior ecosystem service delivery.
This hybrid approach enhances decision-making for urban planners, emphasizing the importance of local objectives and conditions.

Abstract

Abstract With fast urbanization and increasing climate pressures, green infrastructure (GI) has emerged as a feasible sustainable alternative to urban environmental issues. Among the many GI strategies, rain gardens (RGs) and green walls (GWs) are frequently applied for storm water management, thermal insulation, and biodiversity. This study conducts a comparative life cycle assessment (LCA) of RGs and GWs on the basis of a systematic review of 25 peer-reviewed studies, adopting the ISO 14040/14044 standard. Data were taken for each life cycle stage—construction, operation, maintenance, and end-of-life—and normalized per square meter for a 50-year service life. The main environmental impact categories were global warming potential (GWP100), fossil fuel consumption, water consumption, and solid waste generation. Re-CiPe 2016 method of impact assessment was used to ensure comparability between studies. The results show a balance between LCA phases. Green walls have lower construction-phase impacts (e.g.,GWP: 0.58 kg CO₂ eq/m²) due to prefabricated modular units. Rain gardens, on the other hand, have lower operational-phase impacts (e.g., 419 vs. 796 kg CO₂ eq/m² per year), due to passive water filtering and minimal maintenance needs. RGs also outperformed in delivering ecosystem services such as storm water infiltration, groundwater recharge, and urban cooling. The outcome of this study reinforces that no GI system is supreme. Instead, performance is on lifecycle stage and conditions. Deciding on a choice should rely on local objectives energy performance, water efficiency, or biodiversity. The innovation lies in combining spatial-functional performance and ecosystem service valuation with conventional LCA indicators. This hybrid approach bridges the gap between environmental science and applied sustainability by providing a new decision-support system that increases the relevance of life cycle assessment (LCA) for policymakers and urban planners.

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