Software can keep green roof over Torontonians’ heads

A new Toronto city bylaw requiring that certain new buildings install a green roof may bring big environmental benefits.

The “green roof” stipulation is to reduce urban heat, lower energy consumption and ease storm water management.

The sweeping bylaw will affect many new city construction projects.

It’s applicable to residential, commercial and institutional permit applications made after January 31, 2010 and January 31, 2011 for all new industrial development.

Buildings covered by the bylaw are developments with more than 2,000 square metres of gross floor area and have a graduated coverage requirement ranging from 20 to 60 per cent.

The city’s Toronto Eco-Roof Incentive Program helps fund green roof projects with a $50 per square metre, or up to a maximum of $100,000 grant.

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As some architects revisit their plans to accommodate the bylaw, a local geographical information systems (GIS) provider has come up with a software application that enables government and private developers to quickly identify areas and buildings ideal for green roof construction.

ESRI Canada Ltd. distributes ArcGIS 9.3.1, a suite of desktop, server and Web-enabled applications that enable users to overlay GIS-based maps with customizable operational data to suit various business needs.

GIS technology helps users make sense of information that’s commonly used on spreadsheets and databases by putting them on a map and relating them to geographical data.

The tool can be integrated to mapping services such as Microsoft Virtual Earth, which provides area views of the city and thermal imagery tools to identify “urban hot spots” or areas with sparse green coverage, says Alex Miller, president of ESRI Canada.

With ArcGIS, users can focus on a certain topographical area or specific building. The image appears on the computer screen much like a Google Earth page but with greater close-up capability. A pull down menu calculates sunlight exposure and heat reflection of a chosen area.

Bare areas such as parking lots, roofs, and arid ground come up as orange while places with vegetation are represented in green.

ArcGIS also supports Microsoft’s Silverlight Web development platform, according to Christopher North, director, technology strategy, ESRI.

“End users can view … an interactive map, search for and display GIS data features and attributes, locate addresses, identify features, access raster imagery, and perform complex spatial analysis by simply clicking a button or feature on the map,” said North.

The GIS technology, North said, can even be configured to determine if planned structures are bound to violate city codes and regulation.

“Contracting aerial surveying can be expensive,” Miller noted. “A lot of time and money can be saved by using existing bird’s eye view images of the city and analytics tools.”

Miller’s firm  recently opened a green roof a top their headquarters at 12 Concorde Place in North York, Toronto.

Because of existing structures, ESRI five-month-old garden of miniature scotch pine, sage, catnip and other hardy mountain plants covers only five per cent of the roof.

However, Miller estimates its cooling effect on their offices can reduce ESRI cooling air conditioning bill by as much as 10 per cent each year. Because the plants also drink up much of the rain water pouring down on the building, the green roof also reduces storm water ran offs that burden city sewers and pollute Lake Ontario.

The ESRI Canada chief said that full compliance with Toronto’s upcoming roof garden bylaw can potentially save the city some $60 million to $100 million in storm water management cost alone and drastically reduce the cooling expenses of many buildings.

Miller said in a recent test of ArcGIS, ESRI uncovered some information that could be very helpful to Toronto City planners looking to expand the city’s green space.

“We found out that the largest available green roof areas in the city, belong to educational institutions.”  

If and when Toronto decides to use these untapped areas, Miller thinks it would be much easier because the buildings already belong to the city.

Construction of green roofs in Toronto have reached a new high, according to Terry McGlade, manager of Gardens in the Sky, whose Mississauga, Ont-based firms specializes roof garden and green roof construction. “We’ve recently seen a growing demand in new construction and retrofitting of existing buildings for green roof installation,” he said.

Scott Torrance, principal of Toronto-based Scott Torrance Landscape Architect Inc.believes ESRI’s ArcGIS can be a vital tool in the development of more green spaces in Toronto. The tool can help planners identify which areas of the city to concentrate work on, according to Torrance.

“This is a cost effective easy to use tool that provides instant access to information on where the hot spots that contribute to urban heat effect are,” said Torrance who helped build the ESRI green roof.

With a tool like ArcGIS, Torrance said, city planners can build a “green corridor” in Toronto. “The tool can be used to help planners determine where green roofs can be installed to help bridge the network of parks and small environmental reserves in the city,” he said.

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