Implementing green roofs and walls: lessons from European experiences

This report is the response to a policy request submitted by DG Environment to the EC Knowledge Centre for Biodiversity (KCBD) through the KCBD ticketing system. KCBD assigned this to the BioAgora project, to be answered by the Science Service for Biodiversity (SSBD). Green roofs and green walls are proven, scalable solutions for restoring nature in cities, while delivering measurable benefits for climate resilience, biodiversity, energy efficiency, and human well-being. Evidence from case studies across Europe shows that extensive green roofs dominate current implementation, while intensive roofs and vertical greening systems offer higher biodiversity and social value when supported by appropriate design, governance and maintenance. Monitored sites report significant cooling-energy savings, stormwater retention, and support for hundreds of species, particularly pollinators and birds. Results highlight that performance depends on system typology, vegetation diversity, structural complexity, and integration within wider urban green networks, as well as on hybrid governance models combining public leadership with private and community engagement. Participatory approaches, biodiversity monitoring, and multifunctional strategies remain underused but represent major opportunities to increase effectiveness, acceptance, and long-term impact. This knowledge synthesis report directly supports the implementation of the EU Nature Restoration Regulation and related climate, biodiversity and urban policies, by providing actionable guidance for local authorities and urban planners to meet urban restoration targets through building-integrated greenery.