February 18, 2008 - 10:51PM
EDWARDSVILLE
— A “green” roof takes some environmental heat off
humans.
Flat, black impervious surfaced roofs heat up and radiate heat,
but Southern Illinois University Edwardsville students are
helping a company discover how green, modular roofs — a
living plant system that goes on top of the rooftop — can
replace the “urban heat island.”
Green Roof Blocks, a subsidiary of Saint Louis Metalworks Co.,
approached SIUE in fall 2004 to have researchers evaluate its new
product of modular green roof systems. SIUE’s ongoing
research, started in 2005, evaluates the environmental benefits
of green roof implementation; how green roof installation
benefits the building owner; and the performance of various green
roof materials and techniques.
SIUE’s Green Roof Environmental Evaluation Network, or G.R.E.E.N.,
led by SIUE professor William Retzlaff, chairman of the
Department of Biological Sciences, Environmental Sciences Program
at the College of Arts and Sciences, is training and working with
students to evaluate this new green technology.
“An urban or built environment causes an environmental
problem,” Retzlaff said. “Years ago, the ecosystem
there was natural. Now, we’ve created this urban living
space.”
Black asphalt and roofs in urban areas heat up 10 to 15 degrees
hotter than surrounding rural areas, which is called the “urban
heat island effect,” and creates potentially hazardous high
temperatures in inner cities.
“(Urban heat island effect) creates its own atmosphere,”
Retzlaff said.
With a green roof system, Retzlaff said summer roof temperatures
under a planted surface could be 85 degrees Fahrenheit, compared
to 150 degrees on a flat, standard surface.
Also, storm water runoff from flat, impervious surfaces has
caused problems in urban areas, including St. Louis.
The city of St. Louis has a combined storm water and sewage
system. All the storm water runoff ends up at the municipal waste
water treatment facility, causing waste water and runoff to
overflow into the Mississippi and Missouri rivers, thereby
causing contamination downstream, Retzlaff said.
The U.S. Environmental Protection Agency estimated certain green
roof systems could retain five to 10 times more water than flat,
impervious surfaces.
Retzlaff, along with two other faculty members and more than 60
students, have nine green roof projects going at SIUE, with six
on the Engineering Building’s roof, two on a field site and
a green wall by Bluff Hall. G.R.E.E.N. also has seven industry
collaborators and two faculty members at Southern Illinois
University Carbondale.
A new project will start in March to research green roof blocks
for homes with steeped, sloped roofs.
And SIUE is not alone in seeking green solutions. Lewis and Clark
Community College, in its current project with the National Great
Rivers Research and Education Station, is helping develop a state-of-the-art
river research facility. Green elements of the building will
include a vegetative roof, long-wearing bamboo floors, innovative
waste water technology, on-site wind and hydro power, and many
other environmentally friendly and energy-efficient options.
LCCC President Dale Chapman pointed to the college’s current
project with the National Great Rivers Research and Education
Field Station as a prime example of the focus the college has on
green initiatives. This spring, the college will sign the
American College and University Presidents Climate Commitment,
which will pledge the college’s commitment toward climate
neutrality.
“These are really just the first steps in our vision to be a
green campus,” Chapman has said. “We continue to
develop new ideas for our campus and community on a daily basis,
and we intend to take a lead role in providing green solutions
for our campus and the community as part of our education and
research mission.”
SIUE also considers greening part of its mission.
“The green roof project fits the university’s mission,”
Retzlaff said. “Part of its mission is to serve the
community of Southwestern Illinois and inform them of new
technologies.”
The purpose of SIUE’s ongoing research is to continue to
provide the green roof industry with independent, unbiased
information, he said. New SIUE campus buildings are proposed to
have green roofs, he noted.
But Green Roof Blocks already sells green roof systems. Some St.
Louis buildings with Green Roof Blocks’ products include St.
Louis Children’s Hospital, Oak Bend office building and the
headquarters of the Alberici Corp., a construction company. Also,
it sold a 96,000-square-foot green roof system that’s on
Chicago’s convention center, McCormick Place. Two Wal-Mart
Stores Inc. facilities also have green roofs, Retzlaff said; one
is near Chicago and one is in Texas.
He said the developers of the new residential lofts in Alton
considered a green roof.
Green Roof Blocks also has been featured on “Extreme
Makeover Home Edition” and has been invited to exhibit for
the 2008 Beijing Olympic Committee.
Two other benefits of the green roof product are being researched
currently: roof replacement and heat load. If plants intercept
the ultraviolet light, the roof itself lasts longer, Retzlaff
said, because it disrupts the “freeze-thaw” cycle. And
if roof temperatures are lowered, the building’s heat load
is not as high.
“We think if we can demonstrate energy benefits, the use of
green roofs will grow tremendously,” Retzlaff said.
Green Roof Blocks range in cost from approximately $12 to $25 per
square foot.
General green roof maintenance requires one monthly green roof
visit by the owner and once-yearly fertilization. At first, a
system could need to be watered for the first 10 weeks, but
Retzlaff said some plants never have needed water since they were
planted and watered once. The company installs the green roof and
checks the plants once a year.
“It’s designed to be very low-maintenance,”
Retzlaff said.
Two things are important for a successful modular green roof
system: the growing medium and the plants.
It is a living plant system with a growing medium that goes on
top of the roof, so the deeper the medium, the heavier the module.
The medium could be lava rock with composted pine or aggregate-based
with organic material, Retzlaff said.
“A light medium that holds storm water allows the plants to
grow and doesn’t blow away,” he said.
Plants that can tolerate drought are needed. Plants must be able
to survive 30 to 60 days without water and where it gets very hot
and dry.
“Sedums have been used for years in horticulture as ground
cover, and they do really well on the roof,” Retzlaff said.
SIUE’s green roof projects are open to the public. For more
information, visit www.green-siue.com, where detailed research
results are posted. Other Web sites of interest are www.greenroofblocks.com
and www.greenroofs.com.