The Bio Tray™ is the first biodegradable modular green roof system in the U.S. market. Highlighted and developed for Renzo Piano’s green roof for The Academy of Sciences, it achieved the conceptual vision Piano had of integrating the landscape with the building by achieving a curvaceous form not usually associated with green roofs. The roof is planted with four perennials and five colorful annuals creating a habitat for wildlife and beneficial insects while also meeting the aesthetic requirements for the conceptual vision of Renzo Piano. The team at Rana Creek, headed by Paul Kephart, experimented with 29 different plants before arriving at that combination. At 2.5 acres, the roof is the largest swath of native plants in San Francisco. It is the work of a collaborative effort by Renzo Piano Building Workshop (RPBW), Rana Creek, Green Roof Solutions and SWA Group; it would not have been possible without 48,000 Bio Trays.
The Bio Tray was developed specifically for The Academy of Sciences project and was led by the innovations of Paul Kephart of Rana Creek and Kurt Horvath of Intrinsic Landscaping. The two met at an International Green Roof Conference in Switzerland where they started discussing the possibilities of a green roof modular system that is not dependent on plastic. The Bio Tray is an organic, biodegradable modular system that acts as a carrier for green roof media eventually degrading away to leave behind a carpet of vegetation. It is the only modular system in the United States that does not use any plastic. The standard size is 17” by 17” and has three depth options: 3”, 4”, 5” and 6”. Originally, they were 2’ x 2’ and it was found to be too large to handle. The average planted indoor life span is two to three years and only one to two when exposed to outdoor landscape conditions, the coconut fiber begins degrading when it starts to retain moisture. The raw materials required are coconut fiber (coir), a wood frame at the top for stability and natural latex. Lining each tray are 36 strains of fungi, which supply vital nutrients for the plants while also inoculating the soil to start the long-term work of creating a vibrant mychorrizal network. This network is an organic approach to managing landscapes and will ensure the development of a healthy soil profile for the long-term maintenance of the roof.
The main challenge with any green roof system, especially in the United States, is to dispel the myth that they will eventually leak. While many are beginning to realize the benefits of green roofs regarding the urban heat island effect, increased biodiversity in cities, reduction of impervious surfaces and stormwater runoff, energy efficiency and an extension in roof life; the main inhibition to more green roofs being installed is the fear of the roof leaking. All waterproofing for a roof lies beneath a green roof system. The green roof system placed on top of it will insulate the roofing membrane from water pressure during storm events, UV radiation from direct sunlight and thermal flexation during season changes extending the life of the roof and minimizing the chance of that roof ever leaking.-- Vanessa Lindley Palmer