Green Roofs Commercial/Industrial/Institutional
(Ultra Urban Retrofits)
Green roofs can be
integrated into a proposed or existing project to help meet stormwater
management requirements. Beyond stormwater management concerns, many
green roofs in urban areas have been designed with multiple benefits in
mind, such as aesthetic enhancement, improvements in air quality, and
habitat re-creation.
Toronto City Hall
In November of
2000 the Green Roof Infrastructure Demonstration Project was
launched in order to showcase the benefits of green roofs in urban
areas. The project consists of a public-private partnership between
the member companies of Green Roofs for Healthy Cities, the City of
Toronto, the Toronto Atmospheric Fund, the National Research
Council's Institute for Research in Construction and Environment
Canada. The goal of the demonstration project was to generate
reliable technical data on green roof performance in areas such as
energy efficiency, heating and cooling benefits, air quality
improvement, stormwater retention, and the extension of roof
membrane life span and plant survival in the Toronto climatic
context.
1
Green
roof plot at Toronto City Hall
Green Roof Infrastructure Demonstration Project
(Source: Green
Roofs for Healthy Cities)
Semi-extensive green roof plot at
Toronto City Hall
Green Roof Infrastructure Demonstration Project
(Source: Green
Roofs for Healthy Cities)
Components of
the demonstration rooftop include a native butterfly and bird
habitat, urban agricultural plots with perennials and annuals, two
semi-intensive plots featuring a variety of flowering plants, shrubs
and small trees, two extensive plots featuring a variety of sedum
and alpine perennials and, species native to Black Oak Savannah, a
native prairie ecosystem.
For more
information on this project visit
http://www.greenroofs.org/, or please contact
Steven Peck, through the same web site address.
Chicago City
Hall
As a part of the
EPA Urban Heat Island Initiative project a 38,800 square foot
semi-extensive green roof was installed in April 2000 for the Chicago City
Hall. This retrofit application, which cost more than a million
dollars to design and install, was created as a demonstration
project to showcase the benefits of green roofs in moderating summer
temperatures within ultra-urban environments. The landscape design
followed a formal garden plan as opposed to a meadow-like
environment. The project included a wide range of roof landscape
environments, from a 3.5-inch deep 'extensive' system to 24-inch
deep 'intensive' landscape islands. Approximately 14,000 cubic feet
of polystyrene will be used to create the illusion of a rolling
terrain. A drip irrigation system fed partially by water collected
from the adjacent penthouse roof, was also incorporated into the
roof design. The project was completed in the summer of 2001 and
will be monitored for plant survival as well as other environmental
features such as stormwater management.
2
Chicago City Hall
Urban Heat Island Initiative project
(Source:
Roofscapes, Inc.)
Fencing Academy
of Philadelphia PA
An extensive
3000 square foot green rooftop with a meadow-like setting of
perennial sedum varieties was installed on the Fencing Academy of
Philadelphia in the spring of 1998. The installation was a
retrofit design with the performance objective being the restoration
of the pre-development hydrology for the 2-year return-frequency
storm.
Fencing Academy
of Philadelphia PA
Vegetated roof cover
(Source:
Roofscapes, Inc.)
The vegetated
cover has now reached a mature stage of development, creating a
meadow-like setting of perennial Sedum varieties that had
been selected to withstand the range of seasonal conditions typical
of the Mid-Atlantic region without then need for irrigation or
regular maintenance. The appearance of the roof changes with the
seasons. In the spring fescue grass and sedge, along with allium,
burnet and dianthus dominate species. During the summer and fall
months flowering sedum varieties dominate.
The roof cover
is only 3.4” thick, including the drain layer, and weighs less than
5 lb/sf when dry, with a maximum saturated weight of under 17 lb/sf.
The moisture content of the soil media at field capacity is 45%
(volume), and the saturated infiltration capacity is 3.5 in/hr. The
Philadelphia Fencing Academy green roof has been continuously
monitored for temperature readings since its completion and compared
with an adjacent unvegetated roof cover. During the spring and
summer, the daily variation in temperature on the bare roof ranges
up to 90 degrees F (50 degrees C), while the variation under the
vegetative cover is only 18 degrees F (10 degrees C), or less.
2The green roof is growing in
nicely and has met its stormwater management design requirements.
Fencing Academy of
Philadelphia
Vegetated roof cover
temperature data
(Source:
Roofscapes, Inc.)