Green Roofs - Living Architecture Monitor - Summer 2013 - (Page 8)

RESEARCH ESTIMATING GREEN ROOF BENEFITS A GUIDE TO ATTRIBUTING ECONOMIC VALUES TO PUBLIC GREEN ROOF POLICY & INVESTMENT BY: HITESHI DOSHI AND STEVEN PECK, GRP D The use of green roofs can offer tangible solutions to many challenges faced by urban communities. While some benefits are directly measurable and have ‘hard’ values (such as energy savings), many benefits are not readily measurable and their values are difficult to estimate (such as health benefits). Public benefits can be hard, like the amount of jobs created in the community, or they can be soft or indirect, e.g., how the reduction in air pollutants will positively impact community health. ue to the difficulty of directly applying monetary benefits, we developed a guide for attributing economic values to selected hard and soft public benefits of green roofs at the community level. For the purpose of quantifying the public benefits, the benefits of green roofs were broadly categorized into: urban heat island mitigation, improvements in onsite stormwater management, aesthetic improvements, urban food production, carbon sequestration, employment from manufacture, design, installation and maintenance, increase in property values and corresponding increase in municipal tax base, noise attenuation, shading, increase in life of building envelope components, improved biodiversity, incorporation of green products and systems, and reduced flooding (see table). A series of North American economic benefit studies were examined and divided into two broad categories: those that focused on the process of determining the economic benefits and those that provided economic benefits at a community scale. The process of determining these benefits and the approximations of the soft public economic benefits are applied based on square meters of installed green roofing. Based on the results of North American economic benefit studies, it was inferred that the typical cost for a jurisdiction to LIVING ARCHITECTURE MONITOR / SUMMER 2013 / 8 carry out a detailed study of the benefits of widespread green roof program implementation exceeds $100,000. As a result, the four step procedure for determining the economic public benefits, offers jurisdictions a normalized parameter for estimating public benefits prior to conducting a more detailed assessment. The four step procedure is broken down into: determining the scope, estimation of the costs and applicable benefits, normalization of values and calculation of the potential benefits. Determining the scope of the project assesses the policy and program tools used, and and their influence on the total area of green roofs that will result. Regulations that require green roofs and financial incentives should be considered. There is a considerable variation between incentives, however when used in conjunction with one another, the building owner will receive a greater financial benefit. Following the establishment of the policies being used, the annual green roof area that will be implemented is estimated. The procedure for determining annual green roof area differs depending on the type of policy. For example, green roof incentives are typically in the $5 to $7 per square foot range. The estimation of cost and applicable benefits involves several small sub-steps. Determining the average cost of an extensive green roof can be done through a quick survey of designers and manufacturers in the area. Once the average cost has been determined, the financial feasibility of the project can be assessed and the proper regulatory incentives can be obtained. Understanding the public benefits which apply to the community ensures that the design of the green roof will satisfy the different regulations. Following the selection of public values and benefits, the next step is to normalize the values by modifying factors to account for variation in local conditions. In order to normalize the values provided in the table, the following questions should be asked: • Are these the right benefits? • • Are some benefits missing that are unique to your circumstance? Do the values/m² need to be raised or lowered to reflect your specific circumstances? • • What is the cost of a cubic meter or cubic foot of stormwater? What is the cost of energy? Finally, calculating the potential benefits involves applying the modified values to the square meters (square feet) of the green roofs that will result from the program. There are two approaches to calculating the potential benefits. Life cycle cost benefit studies typically range from 25 to 75 years; or you can use the planned length of the incentive. However it should be noted that benefits will accrue to the community long after incentives have expired. The tool provides a basic approach for estimating the cost and benefit of investments and regulatory initiatives for local green roof development. Although far from perfect, the tool does provide policy makers with an approximation of costs prior to conducting a detailed assessment. Hiteshi Doshi is a professor at Ryerson University. Steven Peck is the founder and president of Green Roofs for Healthy Cities. FIND OUT MORE http://ow.ly/kCaip READ THIS ISSUE ONLINE AT WWW.LIVINGARCHITECTUREMONITOR.COM http://www.ow.ly/kCaip http://WWW.LIVINGARCHITECTUREMONITOR.COM

Table of Contents for the Digital Edition of Green Roofs - Living Architecture Monitor - Summer 2013

Green Roofs - Living Architecture Monitor - Summer 2013
Contents
From the Founder
Green Roof Installation Raises Value of Boston Apartment by $2.4 Million
Green Roof Industry Grows by 24 Percent in 2012 & Washington Dc Is #1
Burgeoning Green Roofs and Green Walls Market to Be Worth $7.7 Billion in 2017
Green Roofs Designated as Certified Wildlife Habitats by National Wildlife Federation
On the Roof With … Art Rosenfeld
Estimating Green Roof Benefits
Mind Mapping the Business Case
The Business Case for Investing in Green Roofs in Portland
CITIESALIVE San Francisco Preview
Policy and Standards
Leadership – for the Sake of the Client and the Environment:
Plant – Profitable Green Roof Plants
Project – It Takes a Village: YMCA
Project – Was It Worth It?
New Corporate Members
Professional Calendar
New and Improved Green Roof Training
Submit a Project to the 2013 Awards of Excellence
Journal of Living Architecture Call for Papers
Great Community Resiliency Project Contest
GRHC Buyers Guide
The Case for Green Façades

Green Roofs - Living Architecture Monitor - Summer 2013