Planted roof case studies

GSA has over 80 buildings equipped with green roofs, spanning approximately 2.2 million square feet. That is about 50 acres or 48 football fields of green roofs. This includes what is believed to be the second largest planted roof in the world: the U.S. Coast Guard Headquarters in Washington, DC, which is almost as large as ten football fields.

SSA Building (New Bedford, MA)

The SSA’s need for additional ground floor space encompassed the surrounding lawn so a vegetative roof was designed to mitigate stormwater runoff. The insulating value of the vegetative roof and the building envelope, including high-efficiency glazing and calcium silicate masonry units, resulted in a zero net gain for major heating, ventilating and air conditioning equipment in spite of doubling the square footage and occupancy.

• Building Name: Hastings Keith Federal Building Social Security Administration
• Location: New Bedford, Massachusetts
• Architect: Oak Point Associates
• Contractor: J & J Contractors, Inc.
• Size (Area): Building: 6,000 sf addition + 10,000 sf renovation
• Budgeted Cost: $2.4 million
• Completion: October 2004
• Green roof size: 4,000 sf

NOAA (Suitland, MD)

The NOAA Satellite Operations Center houses environmental satellite operations of national and global significance. This GSA facility not only enhances NOAA’s mission but also expresses the function of the building by exposing the satellite launch black box and associated dishes. The desire to create a low-impact building in keeping with the scale of surrounding structures led to a green roof design that merges with the landscape and has significant stormwater benefit to the Chesapeake Bay.

• Building Name: National Oceanic and Atmospheric Administration
• Location: Suitland Federal Center, Suitland, Maryland
• Architect: Morphosis/Einhorn Yaffee Prescott
• Contractor: P.J. Dick, Inc.
• Size (Area): Building: 208,271 gsf
• Budgeted Cost: $81 million
• Completion: September 2005
• Green roof size: 146,000 sf

US Coast Guard HQ (Washington, DC)

Due to the unique design challenges and requirements in Washington, DC, and specifically this National Historic Landmark site, the U.S. Coast Guard (USCG) HQ building is designed to be low in deference to the existing historic structures and to blend into the hillside which forms a portion of the sloping fringe of greenery or “green bowl” around the city. This design gives the occupants an advantage of views of the Potomac River, downtown Washington, DC, as well as views of the various courtyards of the building.

The green roof plant material is varied. Low growing sedum is used as well as tall and ornamental grasses, and other hearty plants along with some trees. The green roof is expected to lengthen the life of the roofing waterproofing membrane by 2 or 3 times. It reduces the heat island effect and it adds additional insulation to the roof, cutting down on heat gain. The green roofs are not only functional. In some instances the green roofs are courtyards where the occupants can enjoy the planting close up while walking, meeting, or enjoying lunch. Other green roofs are visible in the office and public spaces throughout the building. The USCG HQ green roof is the second largest in the US and the third largest in the world.

• Building Name: US Coast Guard Headquarters
• Location: St. Elizabeth’s West Campus, Washington, DC
• Architect: Perkins+ Will, HOK, WDG
• Contractor / Construction Manager: Clark Construction, Tishman - AECOM
• Size (Area): Building: 1,143,900 gsf / Garage: 804,783 gsf
• Completion: May 2013
• Green roof size: 557,000 sf