4.13

Green Roofs: Supporting Biodiversity, Communities and Climate Adaptation Efforts

The video below defines what a green roof (living roof) is and describes the four main types available, along with their environmental, economic, and social benefits. The four types are:

Extensive: Low-maintenance, not for human use, shallow substrate (less than 100 mm), uses hardy plants like sedum.
Biodiverse: Aims to replicate the local habitat to attract flora and fauna, uses a mounded surface with 100-150 mm substrate.
Semi-Intensive: A hybrid requiring more maintenance than extensive but less than intensive (100-200 mm substrate).
Intensive: Aesthetically similar to a conventional garden, used in high-traffic areas, requires regular maintenance, and uses over 200 mm substrate.

Key benefits discussed include absorbing carbon dioxide and releasing oxygen, reversing the urban heat island effect (reducing air conditioning usage by up to 40 percent), and providing social benefits like improving mental health through gardening.

The video here showcases the world’s largest urban rooftop farm in Paris. It emphasizes its role in environmental, educational, and community building, connecting city residents to nature.

Green roof challenges include high weight load requirements for deeper substrates, especially for food production roofs, necessitating stronger structures. Additional issues are permit complexities for frequently accessed roofs, the need for permanent and clean irrigation, and the risk of contaminant leaching into edible crops.

Further reading, learning and references

New Society Publishers – Have You Ever Dreamt of Having a Roof Capable of Producing Food? https://newsociety.com/blog/2023/11/16/have-you-ever-dreamt-of-having-a-roof-capable-of-producing-food/

Doyle, L. (2021). Essential Green Roof Construction: The Complete Step-by-Step Guide. Gabriola Island, BC: New society Publishers https://newsociety.com/book/essential-green-roof-construction/

Plantation Paris https://www.plantation.paris/

Living Architecture Monitor – Insight Into Germany’s Green Roof and Wall Market, Trends, and Policy https://livingarchitecturemonitor.com/articles/insight-into-germanys-green-roof-and-wall-market-trends-and-policy-f21

© Daniel Mossberg, CEMUS, Uppsala University and Sonali Phadke, studio Alternatives and Stephanie Foote