Barcelona
TOP SEC - Ecological green roofs bringing nature back to cities through metropolitan circularity and community engagement
About the project
Challenged with improving harmony between Barcelona’s human residents and urban wildlife in a context of climate change, TOP SEC offers a groundbreaking solution: transform the metropolises' flat rooftops into naturalised, seasonal green – or brown – spaces that do not need irrigation.
How? By developing an innovative substrate made from high-quality biochar produced from organic waste digestate and pairing it with a comprehensive study to identify the best plant species for these low- maintenance, naturalised roofs.
TOP SEC is being tested in four unique buildings: a public school, an office building, a social housing complex, and an environmental facility. Plus, an educational programme is set to engage the community, changing mindsets and teaching people the benefits of these roofs. It also highlights how to live in harmony with new non-human inhabitants.
TOP SEC is not just about waste management; it is an affordable way to renovate rooftops, improve thermal insulation, enhance water management, contribute to carbon sequestration, and boost urban biodiversity.
Challenges
The metropolitan area of Barcelona’s significant climate challenges include rising temperatures, recurrent heat waves and drought. Dense urban centres and limited green spaces exacerbate these through the urban heat island effect.
Meanwhile urban expansion places strain on natural resources, impacting biodiversity and ecosystem services.
Waste is another major challenge, with a growing need to segregate and recycle biowaste, increasing source-separated organic fractions (OFMW).
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Urban areas are experiencing increasingly longer drought periods and more intense, recurrent heat waves.
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Managing rising volumes of organic waste is increasingly challenging – from collection and treatment to finding new ways to revalorise waste beyond agriculture and composting.
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Developers, entrepreneurs, urban authorities – and the public – often see green roofs as costly and problematic to build and maintain, particularly in dense, vulnerable areas with deficient building stock.
Proposed solutions
TOP SEC offers a naturalised green roof solution that requires no irrigation, exploring technical and replicable options to maximise environmental benefits with minimal investment and maintenance. This approach combines circularity in the lifecycle of materials and resources, innovative substrates, advanced water retention techniques, and carefully selected plant species. Additionally, the project promotes educational activities to raise awareness on the benefits of naturalised roofs.
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Transform flat rooftops into low-maintenance, naturalised and seasonal roofs that retain humidity and do not require irrigation.
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Repurpose the digestate from the organic fraction of municipal waste by turning it into a biochar with high agronomic capacities, to create a substrate for irrigation-free naturalised roofs.
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Create educational workshops to guide the users of the buildings throughout the project, and a service to advise citizens on the multiple benefits of rehabilitating their roofs with the TOP SEC solution.
Milestones
Set-up of a new stakeholder engagement strategy and educational programme
Set-up of 22 trays with different substrate mixtures and construction sections to collect data
End of construction and start of measurements of the TOP SEC roofs on four buildings
Impact evaluation report assesses the TOP SEC solution at building and city levels
Final event to present and showcase TOP SEC results and Innovative Solution Model