Editorial: why a practical guide to rooftop vegetable gardens?

Everywhere in France and around the world, pioneers are taking possession of our roofs, these reservoirs of untapped spaces, to grow tomatoes, du safran, carrots, cabbages, edible flowers, aromatic herbs, etc. but above all to produce new ways of designing the city to retain rainwater, to moderate the effect of urban heat islands, to germinate new links within neighbourhoods, to participate in the food resilience of cities and to welcome biodiversity.

Let the urban and the rural, the mineral and the vegetal, interact

Our wish is that the making of the city in the city makes it possible to preserve the existing agricultural and natural areas, that nature flourishes in the city, on the ground as on buildings, and that roofs become reservoirs of biodiversity, rainwater storages, urban heat island mitigation zones, social link catalysts, fruit and vegetable production areas.

Roof terraces are an under-exploited area in the city and yet of key importance: they can represent up to 32% of the horizontal surface of a city. Urban agriculture on rooftops is therefore an opportunity for local authorities to optimise built-up areas to integrate nature in the city, to participate in the climate resilience of cities, to recreate places where residents can meet and share while creating local jobs by offering functional and easily usable sites. Planners, developers and builders will see it as an asset for urban developments with high environmental and social added value, in line with the growing need of city dwellers to reconnect with nature.

Why a practical guide for those involved in the making of the city?

Developing urban agriculture on rooftops is not just greening the building, it is integrating a project, led by specific stakeholders, with its own operating model, its flows to manage, its needs to be anticipated. It is about understanding the challenges and diversity of urban agriculture, consolidating various skills to carry out the project, mastering different regulations, forging partnerships.

It is therefore to bring these different elements together within a single operational tool that we have written this guide, in the framework of the lab recherche environnement programme.We hope that our book will help local authorities, planners, developers, landlords, builders and managers of property assets to further develop urban agriculture on rooftops, in all its diversity, whether in the form of a shared garden, urban micro-farm, restaurant’s vegetable garden or productive urban farm.

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Structure of the practical guide

To this end, the book provides a review of current knowledge and practices, as well as a forward-looking vision of the building of tomorrow.

Then, all the criteria related to the layout of the rooftop for urban agriculture, whether technical, regulatory, related to flow management, project management, etc. are presented in a precise manner and accompanied by practical tips.

Finally, we offer methodological support to deploy these projects as well as summary sheets for each form of urban agriculture projects and for each production system. Twelve fact sheets presenting practices and feedbacks from rooftops in Paris, Lyon, Brussels and Besançon make it possible to adopt best practices.

Methodology – A guide designed with the players in the making of the city

To create this guide, we have:

• Analysed regulatory documents specific to rooftops or urban agriculture;
• Listed 170 agricultural rooftop projects around the world and analysed 70 French projects;
• Audited twelve sites in Paris, Lyon, Brussels and Besançon to better understand the constraints and present the details that make the difference in a project;
• Met many experts such as personnel from the technical departments of local authorities, construction and development stakeholders, project leaders and researchers;
• Led collaborative workshops on technical subjects;
• Benefited from the feedback of many contributors;
• Monitored urban agriculture projects during the construction phase.

Table of contents

Urban agriculture settles on the rooftops

1. Urban forms of agriculture
2. The advantages of making rooftops fertile
3. The peculiar ecosystem of the fifth facade
4. A shift towards “circular buildings”

Implementation guidelines

1. Getting to know the project area and defining it
2. Identifying the main elements of the roof structure
3. Identifying the necessary flows for a rooftop farm
4. What equipment for more functionality?
5. Anticipating the project management

Project methodology and fact sheets

1. The main project stages for a new or an existing building
2. Regulation and reference documents
3. Fact sheets presenting different forms of urban agriculture
4. Fact sheets presenting practices and feedbacks from rooftop agriculture projects
5. Bibliography