The Federal Government is greening its operations through several innovative projects throughout Washington, D.C. area. One such example can be found atop the new Department of Transportation Headquarters facility near the Navy Yard in Southeast Washington D.C. The roof of the complex sports a 65,000 square-foot garden, consisting of various plants and grasses, which help reduce storm water runoff and pollution flowing into the Anacostia river.
"In Washington there is a combined sewer system," says Paul Elias, senior vice president of construction for JBG Properties, the facility's owners. "Imagine this huge 18-foot diameter pipe, and in the middle of the pipe is this swollen old bowling-alley gutter. That's where the sewage is flowing. During major rain events this thing fills up to 12 or 15 feet, mixing the [rain]water with sewage and it goes straight out into the Anacostia River."
The green area of the roof consists of various drought-resistant succulents like cacti and sedum, which are planted in a mixture of sand and soil. This mixture acts as a sponge, absorbing rainfall during storm events and thus reducing the amount of runoff.
The plants also act as filtering systems that purify the water they absorb. Water that is released as runoff during a storm is clean of air pollutants that cling to rain on the way to earth.
Other possible benefits of the massive rooftop garden include the reduction of energy used to heat and cool the facility. Green roofs absorb less heat from the sun than plain black tar roofs, making the interior of the buildings cooler. As a result, less air conditioning becomes necessary to keep the building's occupants comfortable. In the winter, rooftop gardens provide the opposite effect, shielding the building from harsh winter weather so less heating is necessary.
Similar design efforts are underway for a landscape renovation project at the Environmental Protection Agency's headquarters in D.C.'s historic Federal Triangle area. The agency, in conjunction with the General Services Administration, is working to redevelop the site's various roofs, sidewalks, courtyards and parking lots, which are for the most part impervious to rain.
Efforts to reducing the impact of polluting effects from storm water runoff at the 25-acre site include the construction of absorptive rain gardens (also known as bio-retention cells), permeable paving, sustainable landscaping and a large cistern within one of the building's interior courtyards, intended to capture storm water.
The EPA hopes its redesign efforts at the site will help to demonstrate the feasibility and cost-effectiveness of such projects. To leverage the facility as a demonstration project, the EPA is building an onsite research facility that will allow the agency and local governments to "observe and monitor point source pollution."
The recently opened Food and Drug Administration campus in White Oak, Maryland also utilizes innovative design features intended to reduce energy use and costs. The 3 million square foot facility consists of 14 interconnected buildings powered by an on-site, self-sustaining cogeneration plant that runs on a combination of natural gas and diesel fuel.
The plant is unique in that it harvests waste heat from the engine's cooling system and exhaust stack to provide cooling and heating for the entire complex, thereby avoiding additional fuel consumption through the use of traditional heating and cooling systems.
The facility's main building, called the Central Shared Use Building, also features a green roof as well as windows that open automatically in coordination with the central air conditioning system. Increased use of glass takes advantage of sunlight for heating, and waterless, low-flow plumbing fixtures conserve water usage.
Since the federal government spends one out of every five dollars in the U.S., it's important they lead the way in spending on innovative energy-efficiency and environmentally friendly programs such as these. Mass deployment of new technologies through government procurement will help drive down the costs of green building products for others looking to save a little green in their wallets and on their Earth.