Green Roofs in Cold Climates
Dr. Leonie Nadeau, a faculty member within Biological Sciences (now retired), and her partners in industry worked to determine which Alberta native plant species grow best in Edmonton’s climate. But there’s a catch: they studied how these 17 plant species grow in various depths of growth material placed on Edmonton rooftops. This work is being continued by other NAIT staff who are conducting additional studies of these “green roofs”, also called “living roofs”:
- Dave Critchley, Biological Sciences
- Beverly Bruyere, Landscape Architecture Design
- Dr. Joe Varughese, Bachelor of Technology in Technology Management
In 2009 and 2010, researchers studied the roofs of three different buildings:
- Esak Consulting Ltd.
- Williams Engineering
- the Edmonton Waste Management Centre of Excellence
In 2011, Roofing Evaluation Modules bought from the British Columbia Institute of Technology (BCIT) complemented this research and helped determine heat flow, water retention and runoff on the different types of green roofs.
Of the native plant species studied, native grasses were the most resilient and competitive on roofs. Also, researchers found that, the deeper the material in which the plants were growing, the better the species performed. However, all species survived, and a few grew well in only 8 centimetres of growth media. Growth media that included biochar (a form or charcoal) supported plant species better than a commercial green roof medium or standard topsoil.