On 9 April 2025, at the Kraš venue in Zagreb, a
Nature‑based Solutions Festival (NbS Festival) was held as part of the ARCADIA project - “Transformative Climate Resilience through Nature‑based Solutions in the Continental Biogeographical Region”. The festival brought together nearly 200 participants - representatives of academia, local and regional authorities, civil society and project partners - with the aim of strengthening climate resilience through the application of innovative nature‑based solutions.
The ARCADIA project, funded by the Horizon Europe programme, is focused on accelerating climate adaptation across Europe through the strategic implementation of nature‑based solutions (NbS). The festival enabled the exchange of knowledge, tools and best practices, and offered local and regional stakeholders concrete resources for addressing climate challenges.
As part of the festival programme, the City of Zagreb presented its ActGREEN project and related efforts on a panel dedicated to the topic “Governance, Regulations & Standards”. On behalf of the City of Zagreb,
Irena Matković,
Assistant Head of the City Office for Reconstruction, Construction, Spatial Planning, Building and Municipal Services, participated. She presented Zagreb’s innovative approach to urban greening through the initiative
“Carbon Sink in Your Courtyard”, aimed at reducing the urban heat island effect and improving microclimatic conditions in city neighbourhoods. Through this initiative, the City of Zagreb actively encourages citizens to transform private and semi‑private courtyards into green, climate‑resilient spaces using nature‑based solutions - from rain gardens, permeable surfaces and biodiverse plantings to urban furniture and stormwater management solutions.
Following the success of the 2023 public call for courtyard greening, which received more than 200 expressions of interest, the 2024 call resulted in more than 250 citizen applications. By decision of the Mayor and the expert commission, 25 locations were selected for greening in the 2025/2026 season. The initiative has been formalised through the City’s Courtyard Greening Decision, which defines acceptable interventions - from installing composters to implementing solar lighting.
The ActGREEN project and this specific initiative of the City of Zagreb are supported by the NetZeroCities platform, also funded through Horizon Europe. This model of planning and citizen participation sets new standards in urban renewal and planning, where green infrastructure becomes a shared responsibility.
During the panel discussion, numerous important questions were raised regarding the implementation of the Urban Greenery Renewal Strategy in Croatia (2021). Participants, including
Miljenko Sedlar from REGEA and project partners from ARCADIA and ActGREEN, pointed to the need for clearer definition, regulation and standardisation of nature‑based solutions in Croatia. Examples of misinterpretations were mentioned - for instance, classifying a single climbing plant as a “green wall” - as well as issues related to safety regulations, such as inadequate plant selection for green roofs.
The need to harmonise the legislative framework in the field of NbS was emphasised, as well as the urgent need to adopt standards for green roofs and façades. Currently, such formal standards do not exist in Croatia, but a professional association is being established with the aim of developing them, taking into account European best practices. One of the key questions highlighted was the long‑term maintenance of newly created green areas: who assumes responsibility for maintaining green courtyards - municipal services or residents?
The festival, along with panel discussions and interactive workshops, provided an opportunity to strengthen cooperation among cities, exchange experiences and present advanced solutions that empower local communities in addressing climate change.
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