Transforming Rooftops, Transforming Cities: Building Climate-Resilient Urban Spaces
Cities are at the heart of the climate challenge. With their dense infrastructure, limited green spaces, and rising temperatures, urban areas are among the most vulnerable environments to the effects of climate change. Yet within these concrete landscapes lies an untapped opportunity for resilience — our rooftops.
The Blue-Green Tops project, led by the University of Patras (Greece), explores how transforming rooftops into vibrant ecosystems can help cities cool down, manage water sustainably, and improve quality of life for their residents. By combining citizen science with innovative urban design, this initiative aims to redefine how we think about the spaces above our heads.
From heat islands to cool havens
Urban rooftops, typically built from high heat-capacity materials like concrete or asphalt, absorb and retain heat, contributing to the urban heat island effect — a phenomenon that makes cities significantly warmer than surrounding rural areas. As climate change amplifies heatwaves, this effect increasingly threatens human health, energy efficiency, and urban ecosystems.
The Blue-Green Tops project proposes a solution: transforming conventional roofs into blue-green systems that combine vegetation and water-retaining features. Green roofs covered with plants provide insulation and cooling, while blue roofs capture and store rainwater, reducing flood risks during extreme weather events. Together, they create microclimates that moderate temperature, enhance biodiversity, and improve overall urban livability.
Citizen Science meets urban innovation
The project’s unique strength lies in its citizen science approach. Through the Colouring Cities Research Programme (CCRP) — an open-source platform that allows data on buildings and urban environments to be collected, visualised, and shared — citizens play an active role in mapping and evaluating their city’s rooftops.
Using the CCRP’s infrastructure, participants can gather microspatial data on roofs, including details such as structure, age, material, and exposure to sun and wind. This data helps identify which rooftops are best suited for blue-green transformations and which require structural improvements first.
The initiative builds on earlier successes like Colouring Dresden in Germany and expands them through Colouring Athens and Colouring Istanbul, creating a cross-border network of communities contributing to sustainable urban development.
Athens and Istanbul: Urban labs for change
Both Athens and Istanbul face some of the highest heat risks in Europe, making them ideal pilot cities for rooftop adaptation. In these densely populated environments, every square meter counts — and rooftops represent an enormous, underutilized resource for climate action.
By engaging local citizens, researchers, and stakeholders, the Blue-Green Tops project not only generates scientific data but also builds awareness and participation. Citizens are empowered to understand how their buildings interact with the climate and how small changes at the local level can collectively drive urban resilience.
A model for global urban adaptation
The project’s approach demonstrates how data-driven citizen science can accelerate sustainable transformation in cities worldwide. Its methods — combining open data platforms, local engagement, and environmental design — can be replicated globally, providing cities with tools to adapt to climate challenges in a participatory, cost-effective way.
Ultimately, Blue-Green Tops shows that climate adaptation doesn’t always require building new infrastructure — sometimes, it’s about reimagining the spaces we already have.
Building the future, one roof at a time
By merging technology, science, and community action, the Blue-Green Tops project represents a new generation of urban adaptation strategies. It’s a reminder that resilience starts at the local level — and that citizens can be both the source of knowledge and the drivers of change.
As part of the Flourish phase of the ScienceUs Project, Blue-Green Tops contributes to the broader European mission of empowering communities to co-create solutions for climate resilience. Through its cross-border collaboration and open-data spirit, it offers a scalable model for turning grey rooftops into green, living systems that sustain cities — and the people who inhabit them.
By empowering young people to take part in shaping the policies that affect their future, the project ensures that climate governance becomes more inclusive, dynamic, and future-oriented.
As part of the Flourish phase of the ScienceUs Project, The Future is Climate embodies the European vision of collaboration between science and society. It shows that the path to climate resilience begins with dialogue, empowerment, and shared knowledge — ensuring that the voices shaping tomorrow’s world are heard today.
“Funded by the European Union. Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or European Research Executive Agency. Neither the European Union nor the granting authority can be held responsible for them.”