May 12, 2003—Birds and butterflies will have a new place to frolic—atop the world’s largest living roof on the new Dearborn Truck Plant’s Final Assembly building.
The 10.4-acre living roof, produced by German-based Xero Flor, is made up of a low-growing ground cover called sedum, which can absorb up to 4 million gallons of rainwater annually. The roof is expected to last at least twice as long as a conventional roof since it does not shrink or expand during temperature fluctuations, saving millions of dollars in replacement costs.
It is also expected to insulate the facility, saving 5 percent on energy use during both the summer and winter. It weighs approximately eleven pounds per square foot when soaking wet—fourteen pounds less than they planned for.
Sedum absorbs carbon dioxide as part of photosynthesis, releasing oxygen and reducing greenhouse gases. Other than watering during its early growth stage, the sedum is maintenance free, requiring no mowing or trimming. When fully developed, it will resemble a meadow with small red, white, yellow, and purple flowers.
When rain falls on the living roof, it is absorbed or filtered through plant roots, which cleanse the water of contaminants before it runs into the nearby Rouge River. Rather than being planted in loose soil, sedum on the living roof grows on a four-layer mat-like system that is only three inches thick. The bottom layer is a root-resistant membrane, followed by a drainage layer, a fleece mat, a vegetation blanket of semi-organic material and, finally, sedum plants.
Many other environmental innovations also are being planned or are already a reality at the Ford Rouge Center:
- Native plants will clean the soil around the Ford Rouge Center using a biological process called phytoremediation. Phytoremediation is safer, less expensive, and more environmentally friendly than digging up and hauling contaminated soil to a landfill.
- Phytoremediation plants break down and remove from the soil the polyaromatic hydrocarbons, a byproduct of years of steel manufacturing.
- Special ditches of gravel, sand, and cattails called swales are being installed throughout Ford Rouge Center to mimic the cleaning action of natural wetlands.
- The nation’s largest porous parking lot will be installed on 16 acres at the nearby vehicle shipping yard. Honeycombed with small holes, porous paving lets rainfall and snow seep into underground rock beds, where it is filtered by compacted stones and redirected to natural treatment wetlands.
- Ten huge window boxes called roof monitors and thirty-six skylights will bring daylight into the assembly facility. This system allows up to half the lights to be turned off on sunny days, reducing electricity costs.
