The Sustainable Sites Initiative
Why Sustainable Sites?
Well-designed landscapes promote biodiversity with a mix of native species and ecologically appropriate non-native species.While standards exist for sustainable structuresóìgreen buildingsîóthere are no standards to guide those who want to create sustainable landscapes as there are for green buildings. Yet landscapes have great potential for both environmental good and severe environmental damage. For example:
Greenhouse gas emissions. Vegetation helps reduce the amount of carbon dioxide, a greenhouse gas, in the atmosphere by capturing and storing it for use in producing roots, leaves and bark. In the United States, urban trees capture up to 25 million tons of carbon each year.1
Urban Climate. Urban trees reduce the urban heat island effect and provide windbreaks. A study of five U.S. cities found that the presence of urban trees can result in substantial annual energy savings--$553,000 per year in Berkeley, CA and $187,000 in Cheyenne, WY.2
Biodiversity. Well-designed landscapes promote biodiversity with a mix of native species and ecologically appropriate non-native species. Approximately 85% of the invasive woody plant species in the U.S. were introduced for landscape or ornamental use,3 and approximately 5,000 plant species are estimated to have escaped to natural ecosystems.4 Purple loosestrife (Lythrum salicaria), for example, was introduced as an ornamental plant in the U.S. and has since rapidly and aggressively spread to 48 states, resulting in control costs of almost $45 million per year nationwide.5 Through competition with native plant species, invasive species such as purple loosestrife are a threat to native flora and fauna.
Water waste. Native plants and water-conserving landscapes reduce the use of scarce water resources. The turf grasses used in residential and commercial lawns and golf courses are the single largest irrigated crop in America in terms of surface area, covering an area the size of the state of Mississippi. On average, each U.S. citizen uses 200 gallons of water per day in order to maintain this ìcrop.î
Water pollution. The U.S. Fish and Wildlife Service reported that ìhomeowners use up to 10 times more chemical pesticides per acre on their lawns than farmers use on crops.î6 Careful plant selection and organic soil additions reduce the use of pesticides and fertilizers that can contaminate water. Good design and techniques like rain gardens or swales reduce runoff. 1995 EPA data showed that urban runoff contributed to damaging more than 26,000 river and stream miles. In addition, the National Water Quality Inventory: 2000 Report to Congress identified urban runoff as one of the leading sources of water quality impairment in surface waters.7
Recycling of landscape trimmings to serve as compost, and mulch provides additional benefits to on-site soils and vegetation.Yard waste. Composting leaves and grass is good for the soil, yet leaves and grass comprise as much as 18 percent of landfill volume, with another seven percent consisting of rock, soil and woody landscape waste. In Texas alone, it costs $150 million a year to dispose of this yard waste.8
Public health. Studies show that the visual effect of flowers and plants are good for people. Nursing homes in Texas that incorporated more plants and animals into residentsí daily lives noted a marked decrease in behavior incidents, bedsores and restraints.9 A Chicago study links tree and grass cover to fewer property crimes, fewer violent crimes, stronger ties among neighbors, more frequent use of common neighborhood spaces and a greater sense of safety.10
Energy consumption. Using local, sustainable materials takes less of a toll on our energy supply. The energy demands to produce and transport materials (embodied energy) can account for up 15 percent of a buildingís energy use over its entire lifespan.11
 Nowak, D.J. and D.E. Crane, Carbon Storage and Sequestration by Urban Trees in the USA, Environmental Pollution116 (2002).
 McPherson, Greg, James R. Simpson, Paula J. Peper, Scott E. Maco and Qingfu Xiao. Municipal Forest Benefits and Costs in Five US Cities. Journal of Forestry(December 2005): 411-416.
 Reichard, S.H. and P. White, Horticulture as a pathway of invasive introductions in the United States. BioScience 51 (2001): 103-113.
 Pimentel, D., R. Zuniga, and D. Morrison, Update on the environmental and economic costs associated with alien-invasive species in the United States. Ecological Economics 52 (2005): 273-288.
 U.S.Fish and Wildlife Service. Homeownerís guide to protecting frogs ñ lawn and garden care. Division of Environmental Contaminants (July, 2000).
 U.S. Environmental Protection Agency (USEPA).2002b. 2000 National Water Quality Inventory. U.S. Environmental Protection Agency, Office of Water, Washington, DC. www.epa.gov/305b/2000report. Last updated August 18, 2003. Accessed August 19, 2003.
 Texas Commission on Environmental Quality (TCEQ). A Green Guide to Yard Care. GI-028 (Rev. 6/05).
 Texas Long Term Care Institute. ìEden Alternative: The Texas Project,î San Marcos, Texas: Long Term Care Institute (1999)
 Kuo, Frances E. The role of arboriculture in a healthy social ecology. Journal of Arboriculture 29 no.3 (May 2003): 149-155.
 Thormark, Catarina. A low energy building in a life cycleóits embodied energy, energy need for operation and recycling potential. Building and Environment 37 (2002): 429 ñ 435.
This effort began as separate projects of the Sustainable Design and Development Professional Practice Network of the American Society of Landscape Architects (ASLA) and the Lady Bird Johnson Wildflower Center. In 2005 the two groups joined forces and held a Sustainable Sites Summit in Austin, Texas.
In 2006, the United States Botanical Garden joined as a major partner in the initiative. A Product Development Committee representing 11 stakeholder groups was selected to guide the initiative. In addition, there now are more than 30 experts serving on subcommittees developing sustainable practices for soils, hydrology, vegetation, human well-being and materials. These subcommittees are developing the technical foundation for the standards and guidelines.
The US Green Building Council (USGBC), a stakeholder in the initiative, anticipates incorporating these guidelines and standards into future iterations of the LEED (Leadership in Energy and Environmental Design) Green Building Rating Systemô.
The first interim report on the Standards & Guidelines was released in November 2007.
©2007 Sustainable Sites Initiative