Circular urban farming: shaping the cities of tomorrow

This article is brought to you by Amandine Galli from the Bureau d’Études de Gally.

Reducing greenhouse gas emissions is a top international priority in the fight against climate change, which threatens our entire ecosystem. The construction sector has a crucial role to play. While energy-efficient building renovations are one way to contribute, another promising solution might be found above us—let’s look up and seriously consider the untapped potential of our rooftops!

The GROOF project: rooftop greenhouses for a circular economy

In this context, several European countries joined forces in 2017 for the “GROOF” project, which stands for “Greenhouses to Reduce CO2 on RooFs.” Supported by the INTERREG North-West Europe (NWE) program, which co-funded 60% of the project, GROOF brought together 11 partners from France, Belgium, Germany, Spain, and Luxembourg over seven years.

The project adopted an innovative cross-sectoral approach to reducing CO2 emissions in both the construction and agricultural sectors by combining energy sharing and local food production.

The concept centers on using rooftop greenhouses as efficient systems to:

  • Capture excess heat produced but not used by the building—both actively (via ventilation and heating systems) and passively (an average of 30% of heat is lost through rooftops)—to grow plants.
  • Collect CO2 generated by building occupants and activities to “feed” the plants.
  • Reduce CO2 emissions from transportation by growing vegetables locally.

The ecosystem formed by the rooftop greenhouse and its supporting building requires significantly less energy than if the greenhouse were a standalone facility. Additionally, the greenhouse serves as an external activity while sharing energy with the building, making both structures more efficient.

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The objectives of the project

This international project pursued three main objectives to maximize its long-term impact:

  • Implementing four pilot projects in France, Belgium, Germany, and Luxembourg to demonstrate technical feasibility and profitability.
  • Supporting rooftop greenhouse developers in North-West Europe by providing expertise and sharing feedback.
  • Identifying obstacles and opportunities at the legal, financial, and technical levels to facilitate the implementation of rooftop greenhouses for CO2 reduction, with insights compiled into accessible Guidelines.

    These Guidelines were published at the end of the project and are freely available online.

    The creation of European pilot projects

    After analyzing the state of the art, building four pilot greenhouses, monitoring their performance, coaching over a dozen projects across various countries, and disseminating the Guidelines, the GROOF project concluded in 2023.

    As the project wrapped up, the partners reflected on the future:

    • How can the knowledge gained be utilized further?
    • How can feedback and best practices be shared?
    • How can this expert community be sustained?

    At this turning point, Interreg NWE launched a new small-scale project initiative to support smaller-scale projects over 18 months. The GROOF team successfully applied, resulting in the “CUF Training” project, or “Circular Urban Farm.”

    This new project expanded its focus beyond rooftop agricultural greenhouses to circular urban farms, bringing together experts from construction, energy, agronomy, and economics in France, Belgium, Luxembourg, and Germany.

    Grow the City: A free training for circular urban farming

    After analyzing existing training programs and gathering input from potential project developers, public authorities, and technical experts, the CUF Training project launched Grow the City, the first free online training program in circular urban farming, available in 2025.

    Designed for urban developers, municipalities, planners, architects, project managers, agronomy engineers, producers, and anyone involved in city planning, this initiative—supported by the Interreg North-West Europe program—aims to provide practical skills for designing, building, and managing circular urban farms.

    The training program aims to address key challenges faced by European cities:

    • Socio-economic challenges: Limited resilience to heatwaves, food shortages, and low local value creation.
    • Environmental challenges: Climate change, intensive land use, lack of local energy resources, and wasteful urban farms disconnected from buildings.
    • Skills gaps: Urban developers often lack tools to integrate food production and circular approaches into urban designs.

    By building on GROOF’s knowledge and incorporating circular techniques, the CUF Training project offers comprehensive insights into sustainable food production in urban environments, including: Hydroponics, bioponics, and aquaponics; Circular business models; Energy and waste management; Circular urban farm design and construction

    The project aims to:

    • Increase circularity in building-linked urban farms.
    • Develop off-ground circular urban farms.
    • Equip decision-makers and urban developers with tools for resilient city planning.
    • Build a community of experts and project developers.

    How to join the program “Grow the City”?

    Find below more details about the program:

    • Self-paced modules (MOOCs) with quizzes in English
    • Course access dates: February 7 or 13 to April 25, 2025
    • Open to all involved in urban farm design, construction, or management
    • Time required: 30–60 hours, depending on your profile. Tailored programs are recommended, but participants can choose to take additional courses.
    • Interactive sessions: Four online Q&A and discussion sessions
    • On-site practice: At least one practical session at one of four rooftop farms in Luxembourg (Luxembourg), Paris (France), Gembloux (Belgium), or Damendorf (Germany)
    • Certification evaluations (optional)

    Don’t wait—join us today! Registration closes on January 30, 2025.

    Visit our website Grow the City for more details.

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