GROOF - Greenhouses to Reduce CO2 on Roofs

Project Summary


The potentials of synergies between buildings and integrated rooftop greenhouses are described in previous reports and articles. This article provides an overview of the interim results of Greenhouse Gas Emissions (GHG) of the GROOF pilots. For this topic, the research institutes HS Trier / IfaS and CSTB have developed a method as well as reference scenarios to compare the GROOF pilots with a commercial greenhouse vegetable production.



The GROOF (Greenhouses to reduce CO2 on Roofs) project is an innovative cross-sectoral approach to reduce CO2 emissions in the construction and agriculture sectors by combining energy sharing and local food production.

The idea is to use rooftop greenhouses as a tool to:

  • Recover actively (use of the ventilation system) and passively (insulation effect) the heat produced and otherwise lost by the support building in a horticultural production installed in a rooftop greenhouse,
  • Collect the CO2 produced by human activity and the activities of the support building to feed the plants,

Practically, the project facilitates the emergence of this type of greenhouse on the market by demonstrating and disseminating good practices to actors in the building and agricultural sectors that are favourable to the development of profitable and functional economic and social models.

The project specifically aims to:

  • Identify and reduce market access barriers (urban planning rules, technical regulations, insurance, etc.): GROOF teams studied the practices in different NWE countries as long as the local regulations. The interview of several pioneers such as BIGH (Belgium), Urban Farmers (The Netherlands), Universitat Autònoma de Barcelona (Spain) and others provided valuable information that will be used to produce guidelines for early adopters struggling with the implementation of CO2-cutting rooftop greenhouses.
  • Support the first users in the implementation of their project: 10 early adopters have been selected through an open call and are currently coached by GROOF experts. The success of those 10 different profiles will demonstrate the relevance of several business models involving rooftop greenhouses and is expected to inspire others. You can discover the early adopters here.
  • Experiment and demonstrate the effectiveness of the technology for a representative number of business and social models: GROOF is investing in four pilot projects, designed to prove the effectiveness and sustainability of models related to different types of buildings. They are located in France, Belgium, Luxembourg and Germany. You can discover them here.

The results of each activity will be openly shared on our international community on the online platform Construction21 where regional and national public authorities, SMEs and large enterprises, research centres and general public are invited to interact. 

This community also host a mapping of existing and planned rooftop greenhouse projects in the world. Each project leader is invited to fill in the information of his or her project in order to share it with the world and benefit from the community’s feedback.




The purpose of these guidelines is to help rooftop greenhouses (RTG) project owners to introduce energy, construction, and production synergies with the host building in their business model in order to strengthen its robustness while reducing CO2 emissions.


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Project Partners

  • Université de Liège, Gembloux Agro-Bio Tech

    7 Place du 20 août

    View partner details

  • EBF GmbH

    24 Robert-Bosch-Straße

    View partner details

  • ASTREDHOR: Institut Technique de l’Horticulture

    44 rue d’Alésia

    View partner details

  • Centre Scientifique et Technique du Bâtiment

    88 avenue Jean Jaurès

    View partner details

  • Hochschule Trier Institut für angewandtes Stoffstrommanagement

    9926 Campus Allee

    View partner details

  • Groupe One

    69 rue de la Station
    Braine le Comte

    View partner details

  • Cluster Eco Construction

    1C Rue Eugène Thibaut

    View partner details

  • Universitat Autònoma de Barcelona

    Ed. Rectorat Campus de la UAB s/n
    Cerdanyola del Vallès

    View partner details

  • Les Jardins de Gally

    Ferme de Vauluceau Route de Chèvreloup

    View partner details

  • Institut de Formation Sectoriel du Bâtiment

    5 Zone d’Activité Economique Krakelshaff

    View partner details

  • Conseil de Développement Economique pour la Construction

    5 Zone d’Activité Economique Krakelshaff

    View partner details

Lead partner

Organisation Address Email Website
Conseil de Développement Economique pour la Construction 5 Zone d’Activité Economique Krakelshaff
Name Contact Name Email Country
Université de Liège, Gembloux Agro-Bio Tech Haïssam Jijakli Belgium
EBF GmbH David Volk Germany
ASTREDHOR: Institut Technique de l’Horticulture Guillaume Morel-Chevillet France
Centre Scientifique et Technique du Bâtiment Maeva Sabre France
Hochschule Trier Institut für angewandtes Stoffstrommanagement Karsten Wilhelm Germany
Groupe One Marc Lemaire Belgium
Cluster Eco Construction Hervé-JAcques Poskin Belgium
Universitat Autònoma de Barcelona Xavier Gabarrell
Les Jardins de Gally Nicolas Brulard France
Institut de Formation Sectoriel du Bâtiment Marcel Deravet Luxembourg


Reducing greenhouse gas emissions is a major international concern in the fight against global warming, which threatens our entire ecosystem. The construction sector obviously has a key role to play and, if the energy renovation of buildings is one of the ways to contribute, another solution could well come from higher up... let's look up and seriously consider the potential of our roofs! 

In this context, many European countries are involved in the "GROOF" project, for "Greenhouses to Reduce CO2 on RooFs", with the support of the INTERREG NWE program.

The first coaching sessions took place from 2019 to 2021 with 5 early adopters who could benefit from the expertise of our experts.

2022 marks a new year of coaching with 10 new projects selected, coached by our team of experts. 


Our expertise

  • Construction

Knowledge and expertise in construction design, stability, materials, technical assessment, calculation, risk analysis. Specialisms in roofing and structure. Knowledge in material behaviour and innovative combination. Skills in technical project analysis.

  • Energy

Analysis of the energy flows of the existing building and the project itself, counselling for techniques and measurements to reduce energy demand and implement existing flows to reduce CO2 emissions.

  • Production

The plant production expertise consists both in the design of plant production systems and the management of production. This includes knowledge in growing system, plant nutrition, light, pest and disease management, practical organisation of the work, etc...

  • Economic viability

Emphasis on the viability and durability of the candidates’ project, with the respect of the candidates’ vision. This includes evaluating the stakeholders, the cultural & geographical context, the social fabric, the environmental ambitions, the key threats, etc.


All those 10 projects bring together different greenhouse techniques (hydroponic greenhouses, aquaponics, soil-based vegetable gardens, etc.) as well as different types of projects (educational, social, private, etc.) but all of them focus on ecology and the respect for environmental values.


First coaching: already 10 projects coached since 2019

From September 2019 to September 2020, GROOF has already supported 10 greenhouse projects exclusively located on rooftops, for a total of 175 hours of individual coaching and 5 on-site visits to help them build, develop and implement their project. Then, 5 projects have been selected to pursue the coaching in phase 2 and accelerate their implementation.

Adhoc habitat participatif

Location: Kirchberg (Luxemburg)

Adhoc habitat participatif is a non-profit in Luxemburg aiming at providing affordable housing for a long-term stable community. With their rooftop greenhouse, they will strengthen social cohesion among the residents by creating connection to the environnement.

👉 Read more on the presentation sheet


Location: Brussels (Belgium)

The goal of the greenhouse « Green(s)pote» led by Les amis de l'Entrepote​ in Brussels (Belgium) is to enable the neighbours to garden all year long and produce vegetables such as tomatoes, peas, salads, herbs, etc. A part of the production will directly go to the kitchen of Belgobon, the restaurant just below the Garden.

👉 Read more on the presentation sheet

J'habite mon jardin

Location: Tour (France)

"J'habite mon jardin" project was created by Tours Habitat, the social housing organization of Tours city. The greenhouse is designed as a tool for social inclusion. The production of vegetables and fruits is mainly intended for future inhabitants of the site. The production part will be supplemented by training, animation, communication towards a wide audience, from students ‘groups to urban farmers.

👉 Read more on the presentation sheet

ISA/Yncrea - Lille

Location: Lille (France)

Yncrea engineering school wants to create the first future city’s European demonstrator of food & agriculture. The figurehead of this project will take place in an historical building of the city of Lille called « Palais Rameau » just next to Yncrea’s actual campus.
In this 3000 square meters space, Yncrea will create different areas related to local food production and transformation in the city. Yncrea will create different areas including: a Biohacking space for project based pedagogical approaches (including an urban farm), a food factory, a teaching center, an innovative showroom, a start-up incubator, a vertical farming experimental unit, an open space for the citizens.

👉 Read more on the presentation sheet

Les Petits Poucets

Location: Namur (Belgium)

Les Petits Poucets” will pursue two objectives, firstly it will produce and sell in the city center of Namur healthy, fresh and tasty products, and secondly it will provide training cycles for the project developers.

👉 Read more on the presentation sheet

Culina Hortus

Location: Paris (France)

Cueillette Urbaine is a company that works for the development of urban farming and its benefits for cities. Their goal is to design, install and operate productive and ecological urban farms. They want to create a turnkey urban farm system that consumes little energy and is totally environmentally friendly while being productive. Through Culina Hortus, they plan to build up the first aquaponic and bioclimatic greenhouse farm in France on the rooftop of the 12th floor of a Parisian building (PARIS 12).

👉 Read more on the presentation sheet


Location: Liège (Belgium)

Novacitis is willing to create synergies through the Four food-related units that they will be built up in the former carpentry of the City of Liège : a roof production area, a cafeteria, a local food store and a food processing unit. It will welcome small groups for awareness-building activities offered to local schools and during team-building events organized for enterprises.

👉 Read more on the presentation sheet


Location: Nantes (France)

This project of 400 square meters space is located in Nantes, France, on the roof of an existing 24-apartments residential building. It will offer to inhabitants a new volume to be invested for various common activities: shared garden, urban agriculture experimentations, educational venue for the neighbourhood. The architectural project transforms the image of a social housing neighbourhood.

The SYMBIOSE core project team is composed of the building owner Nantes Métropole Habitat (NMH), Greenhouse-on-top (former Ecotropy), Claas architects and SCE. NMH is the leading coordinator. Greenhouse-on-top is in charge of the coordination of R&D activities.

For the project, they are bound by a consortium agreement with the companies LEGENDRE, CMF and the public research organization IFSTTAR.

👉 Read more on the presentation sheet

Pousses & Vous!

Location: Brussels (Belgium)

Pousses & Vous! has the vocation to develop pedagogical projects in primary and secondary schools, in tight collaboration with the teachers, through field role-playing situations activities. They aim at contributing to the education and awareness of young people on the importance of supporting smart local activity to meet demographic challenges while respecting the environment and being involved in a social approach.

The core business of this rooftop including a greenhouse at See you in Brussels, Belgium, consists in school visits while the harvests represent the by-products socially valued through donations to caritative organizations.

👉 Read more on the presentation sheet

Toits Vivants

Location: Arcueil (France)

The project consists of developing a multifunctional urban greenhouse and a common vegetable garden located on the rooftops of apartment buildings available to the residents.

The implementation of this project was driven by the real estate developer Axone Promotion who wants to provide the residents of its buildings with new common areas in connection with food production. Toits Vivants is an association which aims to develop integrated and participatory edible ecosystems.

👉 Read more on the presentation sheet



Location: Bruxelles (Belgium)

HOUSING MANAGEMENT OF THE CITY OF BRUSSELS : The project is located at the heart of the Brussels Pentagon and consist of the reconfiguration of the Rempart des Moines site: – social housing, divided into 3 distinct architectural typologies and in the centre a public space with its collective social equipment named Pole Rempart.

👉 Read more on the presentation sheet


Location: Lyon (France)

HABITER UNE FERME URBAINE by Ma Ville Verte : Located in the Lyon district in France, Alliade Habitat, social housing developer, will build a Urban farm on top of new apartment buildings.

👉 Read more on the presentation sheet


Location: The Hague (Netherlands)

The New Farm is a redeveloped building into a hub for production companies under 3 central themes: food production, circularity and social innovation.   

👉 Read more on the presentation sheet


Location: London (UK)

Grosvenor Works will expand the existing premises from its current 3 floors, to between 5 and 7 floors. The extension will be crowned with a rooftop greenhouse housing London’s first publicly accessible hydroponics school and high-tech urban farming hub, targeting the creation of new technology-led urban farmers.

👉 Read more on the presentation sheet


Location: Cork (Ireland)

Munster Technological University (MTU) is located outside of the city and positioned on an elevated site, the Tourism and Hospitality building benefits from a feeling of openness with views of the natural environment.

👉 Read more on the presentation sheet


Location: Bruxelles (Belgique)

The project Elizabeth by Green nest is a decrepit building complex including a concert hall that will be renovated and operated with a coherent sustainable and circular approach to address, at its scale, environmental challenges. 

👉 Read more on the presentation sheet


Location: Damendorf (Germany)

The project Himmelgrun Children Nursery will be based on the same model which has been installed at ebf as their pilot rooftop greenhouse but on the ground. The production itself is not sold, but grown with the children and then harvested, processed and consumed directly on site. 

👉 Read more on the presentation sheet


Location : London (UK) is part of a wider project based around bringing aeroponic tower growing directly into both food service and food retail.

👉 Read more on the presentation sheet


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Four Pilot Projects

The GROOF project is investing in four pilots, designed to prove the effectiveness and durability of the models related to different building types, in Belgium, Germany, France and in Luxembourg.

Read more on each project below.



The potentials of synergies between buildings and integrated rooftop greenhouses are described in previous reports and articles. This article provides an overview of the interim results of Greenhouse Gas Emissions (GHG) of the GROOF pilots. For this topic, the research institutes HS Trier /
IfaS and CSTB have developed a method as well as reference scenarios to compare the GROOF pilots with a commercial greenhouse vegetable production.


→ Fermes de Gally - Pilot

Paris, France

Urban roofs remain a little exploited space on which agriculture can develop and provide sustainable solutions to food, economic and climate issues in the city. A new stage in this urban agricultural development is therefore to create greenhouses on the roof that are totally integrated into the building's flow: in particular heat, water and CO2.
In this context, our greenhouse project on the roof of the Ferme Urbaine de St Denis consists of the construction and operation of a productive vegetable garden of 360 m² on the roof of the office and workshop building of the Ferme de St Denis, an urban farm run by les Fermes de Gally. This project will produce hydroponic and substrate agricultural products sold locally, in addition to farm production in the ground.
The greenhouse will have to work in synergy with the support building. Its location on the roof offers the advantage of enhancing the flat roof surface and thus preserve the floor space for the activities of the Kersanté Farm of St Denis (FKSD in the following). This feature will also allow it to easily connect to the heating and ventilation network of the building to recover heat and CO2, contained in the stale air, necessary for the cultivation of plants.

Follow the project of Construction21: Ferme de Gally - FRANCE

→ Université de Liège - Pilot

Gembloux, Belgium

The urban greenhouse of the TERRA building is part of the WASABI platform which brings together in one location all the innovative agricultural production systems adapted to the city and in dialogue with biodiversity. The platform and the urban greenhouse is an institutional project supported by Gembloux Agro Bio-Tech and ULiège.

The urban greenhouse will have an area of ​​198m² and will be divided into three compartments dedicated to research, teaching and demonstration of innovative systems adapted to urban agriculture. The main compartment (132 m²) will be dedicated to research only and will host experiments related to urban agriculture (hydroponics, aquaponics and bio-ponics). The second compartment will be dedicated to the demonstration and experimentation of innovative systems, both for students and for other publics. The third compartment will be used as technical hall. The greenhouse will reproduce conditions suitable for temperate crops such as lettuce and tomato. This greenhouse will be characterized by an accurate climate control, the production system will be modular in order to grow different crops.

Follow the project of Construction21: Université de Liège - BELGIUM

→ EBF - pilot

Bürstadt, Germany

The ebf pilot is a Sunlight greenhouse, which is a modern approach to the classical lean-to concept. It is a greenhouse which is focused on minimal energy demand and utilizing existing energy flows to achieve a year-round operation. In combination with an internally mounted photovoltaic shadowing system, the greenhouse is becoming the worlds first plus energy greenhouse.

The pilot will be installed on an old packaging hall of a former nursery which is now being reinstated by ebf to show how a futureproof and sustainable horticulture business can look like. It will unite modern plant production technics with a social aspect of creating a community starting from an early age. The rooftop greenhouse will be implemented in the whole operation harboring specialized plants like chili peppers which can be harvested all year. Furthermore, the schools and kindergardens of the surrounding area will participate in the operation. Here, they have the possibility to learn and share the knowledge for food production. This gives the opportunity to help people reconnect with food production and give them back the responsibilty for their own food security.

Follow the project of Construction21: EBF - GERMANY

→ SOTA - Pilot

Bettembourg, Luxembourg

The IFSB pilot project will be installed on the extension of its company restaurant. The size of the greenhouse will be 18 x 20 m. The rooftop greenhouse will be located near the training site and will house plants that can be used directly in the restaurant below.

Here, the idea is to integrate a food production greenhouse above a restaurant. A reconnection between local food production and people in order to raise awareness about their food. In addition, a corridor will allow visibility over the production area without disturbing it.

The connection to the building to recover CO2 and heat makes sense for the construction sector. Indeed, this sector in Luxembourg will thus be able to have a project integrated into the building allowing a recovery of CO2, a future challenge for this sector.

Follow the project of Construction21: SOTA- LUXEMBOURG

Groof Partners

GROOF project is coordinated by the CDEC (Conseil pour le Développement Economique de la Construction), with the support of the INTERREG NWE programme, and carried out with eleven partners (public and private) from Luxembourg, France, Belgium, Germany and Spain.

Each partner brings valuable skills and knowledge to the project such as construction process and methodology, building energy management, urban agriculture development, knowledge of plants and cropping systems, entrepreneurial skills, socio-economic skills, etc.

Find the partners interviews here.

Company Country Field of expertise
Conseil de Développement Economique pour la Construction Luxembourg Building/construction

Université de Liège – centre de recherches en agriculture urbaine et smart city Institute 

Belgium Agro-socio-eco
EBF GmbH Germany Energy/Technic
ASTREDHOR: Institut Technique de l’Horticulture France Agro-socio-eco
Centre Scientifique et Technique du Bâtiment France Energy/Technic - Building/construction
Hochschule Trier Institut für angewandtes Stoffstrommanagement Germany Energy/Technic - Agro-socio-eco
Groupe One Belgium Agro-socio-eco
Cluster Eco Construction Belgium Building/construction
Universitat Autònoma de Barcelona Spain Energy/Technic - Agro-socio-eco
Les Jardins de Gally France Energy/Technic - Agro-socio-eco
Institut de Formation Sectoriel du Bâtiment Luxembourg Building/construction

With the support of the Walloon Region


Increase building's attractivity

Posted on

A rooftop greenhouse (RG) is not a simple agricultural production tool. It is a way to increase the whole building value, and to show your interest in modernity and ecology. Rooftop greenhouse can be used to product fruits and vegetables only, in an intensive way, or can also be seen as a place for people to meet and exchange. Read More

Festa de la Ciència, Barcelona

Posted on

This past weekend, 26 and 27th of October, the Sostenipra research group from ICTA-UAB, along with the GROOF project took part in the Science fair “Festa de la Ciència” coordinated by the City of Barcelona. It was the 13th edition performed at the public space “Moll de la Fusta” during which lots of citizens who were interested in science and technology got the opportunity to be closer to the different topics related to technological advances and catch up on current problematics that science and technology are helping to solve. Read More

Press release from Sostenipra

Posted on

On the 28th of October 2019 the GROOF partner Sostenipra from the institute ICTA-UAB based in Barcelona, joined with Entorno XXI, Eixverd, 4A + A Arquitectura Ambiental, COAC and with the support of the City Council of Barcelona, organized a seminar discussing the barriers and opportunities of the new use of the urban rooftops. These were identified by the actors involved in the Green Cover call (Cobertes Verdes) promoted by the City Council of Barcelona as owners, communities, administrators, technicians and the administration itself. Read More

Saving CO2e emissions with Rooftop Greenhouses – But how to prove it?

Posted on

The project GROOF aims to reduce Greenhouse Gas (GHG) emissions expressed in CO2e by implementing greenhouses on rooftops for local production of vegetables. The reduction of GHG emissions is expected to result from the synergy effects of building and rooftop greenhouse (RTG), such as recovering heat losses from the building below to heat the RTG, and from reduced transport emissions. The questions are: How can we prove the emission saving from the four GROOF pilots? And compared to which greenhouse production do we save CO2e emissions? Read More



Press releases of the coaching :

         -  Download in English

         -  Download in German

          - Download in French


Final Press releases  :

   -  Luxembourg

   -  Belgium

   -  Spain

   -  France

   -  UK - Ireland

  -  Germany







                                                                    MEDIA TOOLKIT



What expertise do you bring to GROOF project?

"We offer knowledge in circular economy and material flow management, especially in regards to energy and resource efficiency and management. HS-Trier/IfaS has also an expertise in environmental assessment methodologies, such as greenhouse gas emission accounting, in order to contribute to the identification of potentials to improve buildings’ environmental performance. Thus, we contribute to GROOF with technical support including technical monitoring of CO2e performance in order to maximise emission savings."

Thomas Anton: Hochschule Trier Institut für angewandtes Stoffstrommanagement, Germany

"Innovation, sustainability, health, three key words representing the impact of GROOF project!"

Pierre Raulier, Project Manager, Centre de Recherche en Agriculture Urbaine, Université de Liège, Gembloux Agro-Bio Tech, Belgium

Quelles seraient les principales raisons pour un développeur de projet d'installer une serre sur toit ?

"Au Luxembourg, un maître d'ouvrage pourra se convaincre de faire une serre sur le toit de son bâtiment en prenant en  compte les arguments suivants :

  • utiliser et rentabiliser un espace perdu
  • augmenter la performance de son bâtiment grâce à un système qui isole, voir chauffe son bâtiment tout en s'autofinançant
  • apporter une plus value dans la vie sociale des bâtiments de logement ou tertiaires."

Marcel Deravet - Sustainable construction project manager, Institut de Formation Sectoriel du Bâtiment, Luxembourg

What were the motivations of the Universitat Autònoma de Barcelona (UAB) to get involved in GROOF project?

"Transfer knowledge accumulated during the last ten years of work and research within ICTA-UAB in urban agriculture in southern Europe. Also, help promote Urban Agriculture in cities and, in this way, reduce CO2 emissions in buildings and make horticultural production more circular."

Xavier Gabarell Durany, Projet Leader, Universitat Autònoma de Barcelona, Spain.




General contact:


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The social media for sustainable buildings and cities

Follow our activities

Join our community on Construction21


Since 2017, the GROOF project partners have joined efforts to encourage the utilisation of rooftop greenhouses in Northwestern Europe.

The Final Event allowed to present all the deliverables form the projet, encouraged the discussion and showed all participants concrete cases. 


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