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| The construction of the green roof was completed by applying a conventional roof system over the structural metal deck. |
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Resulting Design
The resulting design not only
succeeded in achieving the initial objectives, it has become a template for
future Ford Manufacturing facilities. The design allowed the building to
achieve LEED status through the use of structural steel, natural lighting and
the green roof assembly. Structural steel contributes to the building’s
sustainability because it is nearly 100 percent recyclable. Steel is one
material that can be recycled repeatedly without losing quality. The structure
was erected using nearly 8,500 tons of structural steel.
Natural lighting was also implemented in the design to reduce large-scale
energy usage. To help provide natural lighting into the interior areas a total
of 36 gabled skylights were installed in the roof covering the manufacturing
area.
In addition, a total of 10 monitors, each 33 feet, 4 inches by 100 feet, were
installed over the employee mezzanine. These installations provided natural
light into the building and reduced the need for artificial light during the
daylight hours. Photo sensors were installed in the artificial lighting to
brighten or darken the lights as needed. This allows for an even distribution
of light throughout the facility when the sun is in the clouds. To further
enhance the natural lighting, all of the exposed steel was painted a bright
white to provide reflectance and to lighten the spaces.
Largest Garden Roof
When the Ford Dearborn Truck
Assembly Building
opened in 2004 it had the distinction of housing the largest “garden roof
assembly” in North America — perhaps the
world. The 454,000-sqaure-foot (about 10 1/2 acres) living roof area was
designed to control the water runoff from the roof area to the aging
underground infrastructure. The actual roof construction was completed in 2002.
As the roof enters its sixth year, we thought it would be a good idea to find
out how the industry’s most famous roof has performed to this point.
On a cold Michigan morning I sat down with
Roger Gaudette of Ford
Land to talk about the
performance of the garden roof. Gaudette served as the liaison between
McDonough, Giffels, Walbridge Aldinger (general contractors) and Ford. His involvement
with the project was from inception of the project in the late 1990s through
2006, when he was reassigned within Ford
Land.
“The roof has performed extremely well,” Gaudette said as a fresh blanket of
snow covered the grounds of Ford Land’s offices in Dearborn, Mich.,
which are in the shadows of Ford World Headquarters and the Rouge Plant. “I do
not believe there have been any issues with the roof except for some shrinking
or pulling in of the garden area from the L-shaped metal that held it in
place.”
This issue did not affect the membrane and was filled in with sedum matching
the original construction. There have not been any reported leaks to the roof.
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| The Ford Dearborn Truck Assembly Building opened in 2004. |
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Roof Construction
The construction of the roof was complete by applying a conventional roof
system over the structural metal deck, Gaudette said. “This gives us the
opportunity to add garden components to the other areas in the future,” he
commented.
The roof construction consisted of a modified bitumen roof membrane set over rigid
insulation. The SBS Modified Membrane consisted of a base ply and cap sheet set
in hot asphalt. Isocyanurate insulation was fastened through the galvanized
metal deck and cover board insulation was set in hot asphalt over the
isocyanurate layer.
The garden roof assembly consisted of protection board; a thin, four-layer
growth media/drainage mat system, and a low-maintenance perennial ground cover
called sedum were placed over the membrane.
Gaudette traveled with members of the design team to Germany prior to the roof
design to inspect garden roofs completed using Xero Flor, an international firm
specializing in green-roof and other related systems that were used on this
project.
The primary intent of the living roof application was to filter the storm water
and minimize the storm water runoff from reaching the underground
infrastructure. Storm water becomes saturated and is retained within the
system. The total building size is 1.15 million square feet and the capacity of
the runoff would exceed the capabilities of the complex’s aging (early 1900s)
sewer system. The cost of a new sewer system would have been expensive and
could have jeopardized the entire project.
Water Runoff Rates
Ford has conducted testing on the completed roof system to decipher water
runoff rates, Gaudette stated. “What we tried to do once we got the roof on and
established was to test water runoff rates during different storms,” he said.
Ford hired Giffels to test water runoff by setting up a matrix and monitoring
each rainfall.
“The matrix was set up with heavy rains — long duration, heavy rains — short
duration all the way through light rains — short durations,” Gaudette said.
“They analyzed the water runoff composition to determine the extent of sedum
loss and they looked at different areas of the building for the water storm run
off plan.”
Preliminary testing indicates that the system has achieved its objectives
despite a thin (average 2 inches) sedum layer application.
Landscaping a Living Roof
WH Cannon a local landscape company that Ford has hired for this building has
completed maintenance of the living roof. Gaudette indicated that the
landscaping company has annual responsibility “of checking the viability of the
system, determining if fertilization is required, applying it and working with
the water irrigation.”
Gaudette stated that watering has been limited to the dry season of the year,
which is usually in July and August.
Application of the living roof has stimulated the habitation of the wildlife on
the site. Gaudette said he was surprised by the amount of habitat on the roof.
“From my perspective, one of the surprises has been the amount of wild life,”
he said.
Gaudette noted the abundance of nestling killdeers, Canadian geese nests,
insects, bee’s and dragonflies that are living on the roof.
“From a habitat perspective, it has done very well,” he said.
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| The 454,000-square-foot living roof area of the Ford Dearborn Truck Assembly Building. |
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Challenges and
Complexities
A project of this magnitude was not without challenges and complexities. The
physical size of the project and rigid schedule demands made the project
challenging. Integrating environmental design into a blue-collar construction
community was also complex. Gaudette noted that one of the major challenges of
the project was getting approvals from the city of Dearborn.
“The challenge became bringing them up to speed with what we were trying to
do.” Gaudette said. “This construction was new to the municipality and they
were trying to interrupt codes.”
“They (the city of Dearborn) were interested in determining what does it mean
when you put a green roof on a building and they were concerned about fire
codes what does it mean from a fire protection standpoint,” Gaudette said,
indicating that “getting everybody on the same page — including internal Ford
employees — and convincing them that this something that is viable and a good
thing to do was a challenge.”
Gaudette credited the team approach as the reason for the success of this
project. “We had a goal that we were going to incorporate and we were not going
to let anything get in our way of achieving these goals,” he said.
Overall from a design and application perspective Gaudette feels that Ford
reached its goals on this project.
“I think we first looked at the roof and we knew that energy savings itself was
not going to be the driving factor,” Gaudette said. “I think it was everything
together. The longevity of the roof combined with the environmental aspects and
some energy savings were the three key items that pushed us to do this.”
In Conclusion
Since the completion of the Dearborn Truck Assembly
Building, Ford has applied living
roofs on two facilities; one in California and
another at their World Headquarters in Dearborn.
Gaudette said he is optimistic about the further application of living roofs at
Ford facilities.
“I think we hoped that this would be one of a number of roofs that we would
start and I think we are looking to see how this will perform and what the
affect on the actual membrane is before we continue down the road with anything
of this magnitude,” he said. “We will look at facilities as we build and expand
and look at all environmental aspects, which will include green roofs as part
of the agenda to achieve LEED certification.”
