Green Roofs - Living Architecture Monitor - Fall 2010 - (Page 34)

GRHC UPDATE MACRO-SCALE FOOD PRODUCTION By Steven W. Peck GRADUATE STUDENTS POWER A VISIONARY LOOK AT THE POTENTIAL OF ROOFTOP AGRICULTURE IN TORONTO, CANADA With ties to shrinking farmland, food security, foodmile emissions and sustainability, the challenge facing urban centres today is integrating food production into the cityscape. Green roof-based food production is a viable method of doing exactly this. In 2008-2009, graduate students Stacey McDonald, Kelsey Norman and Nina Damsbaek from the University of Toronto, Masters in Public Policy program were asked by GRHC to develop and implement a method of estimating the multiple benefits of widespread food production on the rooftops of Toronto: a theoretical case study of widespread rooftop urban agriculture. Here is a brief summary of their non-peer reviewed findings. he overall purpose of this research effort is to design a theoretical, case study rooftop – in terms of dimension and capacity – and develop indicators that would estimate and evaluate the effective implementation of rooftop food production for a rooftop of this scale. The research extrapolates and elaborates on existing data, from both the theoretical case as well as from other jurisdictions, and forecasts the costs, savings and other benefits of green roofbased food production. This research has generated a scenario that details the planning and practical application of rooftop food production for the City of Toronto, including what opportunities there are (and should be) for funding and incentivizing such projects. Estimated values were calculated for a 350-square-meter intensive green roof and then extrapolated to a larger scale – 50 million m2 for the following: Seven crops that have demonstrated an ability to grow on rooftops in the area and which have the highest yields (see table). • The design, construction and annual maintenance costs of the green roofs. • The amount of water and fertilizer required as inputs. • The estimated yields of produce by weight. • The estimated market value of the produce. • Estimated greenhouse gas (GHG) emissions reductions through less importation of food from the United States • T EXPECTED YIELD AND RETURNS FOR ROOFTOP FOOD PRODUCTION – CITY OF TORONTO Commodity Expected Yield kg/m2 0.55 3.78 2.01 0.95 3.88 8.05 1.77 Expected Yield kg/50m2 27.46 188.86 100.32 47.64 193.90 402.39 88.55 1,049.11 Expected Yield kg/50 million m2 27,460,796.77 188,862,476.1 100,316,047.5 47,635,697.8 193,903,421.4 402,386,047.5 88,547,664.11 1,049,112,151 Average Calculated Price in Cdn. $/kg 1.89 0.76 1.95 4.44 0.79 1.87 2.20 Expected Return ($/m2) 1.04 2.87 3.91 4.23 3.04 15.05 3.89 Expected Return for 50m2 ($) 51.83 143.54 195.49 211.62 152.21 752.46 194.36 1,701.52 Expected return for 50 million m2 ($) 51,832,253.9 143,535,481.83 195,490,897.57 211,621,587.48 152,214,185.81 752,461,908.74 194,362,122.73 1,701,518,438.06 Beans Carrots(2) Cucumbers Lettuce(3) Dry onions Tomatoes Peppers Total (2) Includes baby carrots and regular carrots (3) Includes leaf and head lettuce // Source: Statistics Canada. Table 001-0013 - Area, production and farm value of vegetables, annual (table). CANSIM (database); Using E-STAT (distributor). www. (accessed: November 13, 2008) 34 LIVING ARCHITECTURE MONITOR FALL 2010

Table of Contents for the Digital Edition of Green Roofs - Living Architecture Monitor - Fall 2010

Green Roofs - Living Architecture Monitor - Fall 2010
From the Founder - Urban Agriculture
Strata - T.O.’s New Green Roof Construction Standard
On the Roof With…Richard Conlin
Project - Farming for the City
Beekeeping - Diary of an Urban Apiarist
Exemplary Design - GRHC’s 2010 Awards of Excellence Winners
A Green Roof That Moves
Steeped in Ecological Design
Creating Community
A Model of Municipal Leadership
A Green Roof That Works
Like a Grassland Stream
Prairie in the City
Recycling Rainwater
Research - Increasing Urban Food Security With Extensive Green Roofs
Economic Valuation of a Rooftop Food Garden
Grhc Update - Macro-Scale Food Production
New Corporate Members
New GRPs
On Spec - Urban Agriculture — Hero or Hype?

Green Roofs - Living Architecture Monitor - Fall 2010