Green roofs and green walls are no longer niche design features but proven, scalable nature-based solutions that can significantly enhance biodiversity, climate resilience, energy efficiency and human wellbeing in European cities. This is a central finding of a new knowledge synthesis report prepared by the Science Service for Biodiversity that is being developed by BioAgora in response to a relevant knowledge request submitted by DG Environment to the EC Knowledge Centre for Biodiversity ( KCBD ).
The report, titled Implementing green roofs and walls: lessons from European experiences , draws on extensive scientific literature, expert knowledge and 46 real-world case studies from across Europe to assess how building-integrated greenery can support urban ecosystem restoration and climate adaptation objectives. It directly supports the implementation of both the EU Nature Restoration Regulation (NRR) and the EU Biodiversity Strategy for 2030, particularly their urban ecosystem restoration/greening targets, by providing practical guidance for local authorities, planners and policymakers.
Evidence-based benefits for cities
According to the report, green roofs and green walls deliver measurable benefits across multiple policy domains. The projects examined in the report demonstrate substantial stormwater retention, reductions in urban heat stress, energy savings for buildings, and support for urban biodiversity - including pollinators, birds and other species that inhabit urbanised areas.
Extensive green roofs remain the most widely implemented system across Europe, largely due to their low weight, relatively low cost and compatibility with existing buildings. However, the report highlights that semi-intensive and intensive green roofs, as well as vertical greening systems, can deliver significantly higher biodiversity, social and microclimatic benefits when supported by appropriate design, governance and maintenance frameworks.
Green walls - ranging from traditional climbers to engineered living wall systems - are shown to contribute to cooling, improvement of air quality and habitat provision, particularly in dense urban areas where ground-level space is limited.
Supporting the EU climate and biodiversity goals
The report situates green roofs and walls within the broader EU policy landscape, showing how they contribute not only to the NRR, but also to the EU Biodiversity Strategy for 2030, the Energy Performance of Buildings Directive, EU climate adaptation strategies and urban water management frameworks.
By transforming underused rooftops and façades into functional green infrastructure, cities can expand urban green space without competing for scarce land. These systems also act as ecological “stepping stones”, strengthening connectivity between fragmented habitats and supporting pollinator recovery - a key EU priority.
Design, governance and long-term performance matter
A key message of the report is that performance depends on how green roofs and walls are designed, implemented and managed over time. Biodiversity outcomes are strongly influenced by substrate depth, vegetation diversity, structural complexity and integration into wider urban green networks.
The report also identifies governance and financing as major barriers to wider uptake. Fragmented regulations, skills gaps, and uncertainty around maintenance responsibilities continue to limit implementation in many regions, particularly in parts of Eastern Europe.
Successful examples across Europe demonstrate the high value added of hybrid governance models that combine public leadership with private investment and community engagement. Participatory approaches, biodiversity monitoring and adaptive management are highlighted as underused but high-impact strategies for improving long-term effectiveness and public acceptance.
Actionable guidance for local authorities
Based on its analysis, the report offers clear policy options for cities and regions. These include embedding green roofs and walls into spatial planning and building codes, introducing targeted incentives, and using performance-based planning tools to prioritise multifunctional outcomes.
The report also highlights emerging innovations, including bio-solar roofs that combine vegetation with photovoltaic systems, blue-green roofs for enhanced water retention, and the use of digital tools, sensors and remote sensing to support monitoring and decision-making.
A strategic asset for Europe’s urban future
By consolidating evidence from both research and practice, the report significantly reduces uncertainty around the utility of green roofs and walls. It provides a robust, action-oriented knowledge base to help cities meet restoration targets while improving quality of life for urban residents.
As European cities face increasing pressures from climate change, biodiversity loss and urban densification, the report concludes that building integrated greenery should be treated not only as an optional add-on but as essential infrastructure that strongly supports in the transition toward resilient, healthy and nature-positive urban environments.
About the report
The report was prepared by a multidisciplinary expert group coordinated by the BioAgora project and the Science Service for Biodiversity, in response to a policy request from the European Commission’s Directorate-General for Environment to the EC Knowledge Centre for Biodiversity (KCBD). It is published by the Publications Office of the European Union and is available under a Creative Commons Attribution 4.0 licence.
Access the report here .
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Funding statement:
Funded by the European Union under grant agreement No. 101059438, BIO-Agora (Bio Knowledge Agora: Developing the Science Service for European Research and Biodiversity Policymaking). Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Commission. Neither the European Union nor the granting authority can be held responsible for them.
Citation:
Enzi, V., Manso, M., Aires, A., Catalano, C., Gedge, D. et al., Implementing green roofs and walls: lessons from European experiences, Vierikko, K., Orta-Ortiz, M.S., Nieminen, H., Vasilakopoulos, P. and Velasco Gomez, D.M. (editors), Publications Office of the European Union, Luxembourg, 2026, https://data.europa.eu/doi/10.2760/8059292, JRC145552.