Green Roofs - Living Architecture Monitor - Winter 2010 - (Page 27)

VIEW ONTO A GREEN ROOF Assuming that having a view onto a green roof has a similar effect to new tree plantings, we estimate the value of the benefit accrued to owners of properties to be nine percent of the value of the portion of a building that affords a direct view onto a green roof. This is based on Wachter’s (2004) finding that tree planting increases property values up to nine percent. Where neighbours of the green rooftop are concerned, we assume that greening a rooftop is equivalent to tree planting at-grade. For them, the greening of the rooftop has much the same effect as tree planting – it adds greenery but does not change the amount of green space to which they have access. We do not attribute any increased value to a green roof without trees. For the purpose of estimating the value of the benefit for a whole building, we assume that only half the neighboring storey’s above the green roof are oriented so as to afford a view onto it. The increase in property value that accrues to a building with a view onto a green roof can therefore be estimated using the following formula: AREA-WIDE BENEFIT The above stated formulas are intended for calculating the value of proximity benefits that accrue to individual properties. Municipal decision makers may be more interested in the total, area-wide increase in property values resulting from a green roof project. In this case, it is necessary to sum the values of the benefit accruing to the host property with those accruing to neighboring properties. Toronto. The garden is accessible to the residents of the host building and visible from a 14storey residential building across the street. Using the formulae given above, the total property value increase due to this roof garden can be estimated at $2.3 million. D Dr. Ray Tomalty, Principal of Smart Cities Research Services and adjunct professor of Planning, McGill University and Bartek Komorowski, Senior Researcher, Smart Cities. Dr. Tomalty will be presenting his findings on the soft benefits of green roofs in Washington D.C. on June 2. REFERENCES Crompton, J. (2005). “The Impact of Parks on Property Values: Empirical Evidence from the Past two Decades in the United States.” Managing Leisure 10(4), 203-21. Voicu, I. & Been, V. (2008). “The Effect of Community Gardens on Neighboring Property Values.” Real Estate Economics 36(2), 281-243. Wachter, S., 2004 The Determinants of Neighbourhood Transformation in Philadelphia - Identification and Analysis: The New Kensington Pilot Study. University of Pennsylvannia, The Wharton School. The Monetary Value of the Soft Benefits of Green Roofs, CMHC 2009 (to be published in 2010). btotal = ∑bn WHERE: btotal = total area-wide property value benefit ($) bn = property value benefit of an individual property ($) To summarize, properties with accessible green roofs are subject to a 20 percent property value premium, while those with rooftop food gardens gain seven percent in property value. Neighbors of both types of green roofs also stand to benefit significantly from their presence. Those who have views onto a green roof could gain up to 4.5 percent of property value, while those adjacent to rooftop food gardens could gain from two percent to seven percent. It should be noted that the sum of the all the property value gains accruing to neighboring properties could be considerably larger than the value of the benefit accruing to the host property. Among the soft benefits examined by the authors, the property value benefits are by far the most significant. For example, a recreational roof garden was built on a four-storey commercial building at 401 Richmond Street West in 1 b = 0.09 – hv-h vv 2 ––– hv hv-h b = 0.045 ––– vv hv WHERE: b = value of benefit ($) vv = value of neighboring property with a view onto the green roof ($) h = height of the green roof host building (storeys) hv = height of the building with a view onto the green roof (storeys) For the purpose of estimating the value of the benefit for a single unit in a building that has a direct view onto a green roof, we propose using the following formula: b = 0.09 • vv LIVING ARCHITECTURE MONITOR WINTER 2010

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

Green Roofs - Living Architecture Monitor - Winter 2010
Contents
Laying Roots for Green Jobs
Outstanding Student Design
Passing of a Legend
New Federal Stormwater Guidelines From EPA
Partnering Science with Service
On the Roof with...Eden Brukman, Reg. Arch., LEED(R) AP
The Leaf Effect
Who Owns the Green Roof?
Planting the Federal Inventory
Curb Appeal
Maintenance Matters
Professional Development Update
Professional Calendar
Congratulations New GRPS
Welcome New Corporate Members
Green Roof Energy Calculator
Doing No Harm

Green Roofs - Living Architecture Monitor - Winter 2010