The sustainable sites initiative
The greenbuild ethic—less waste, more efficiency—has gone mainstream. City after city is requiring its new construction projects, both public and private, to adhere to green building standards. The architects, developers and builders of America have had to get smart, and quickly, about what elements count most towards a building’s greenness. The metrics provided in the U.S. Green Building Council’s voluntary LEED standards (Leadership in Energy and Environmental Design) have largely defined the goals of the building industry’s green-ward turn, but in the council’s urgency to release its standards to an eager building community, the benefits offered by greener sites and greener landscapes were neglected.
Those of us who work with landscapes understand that they can have a powerful effect on the larger environment. In recent years, those effects, both positive and negative, have been studied by scientists and engineers around the world. The American Society of Landscape Architects (ASLA), together with the Lady Bird Johnson Wildflower Center and the United States Botanic Garden, is pulling together this research to formulate guidelines for creating sustainable sites. These guidelines will supplement the voluntary LEED standards and bring site issues under the greenbuild umbrella.
Called the Sustainable Sites Initiative (www.sustainablesites.org), this interdisciplinary coalition is addressing land development and management practices both for sites with buildings, and for parks and other open spaces. Standards for sustainable sites are expected in spring 2009. A rating system much like LEED will recognize performance in meeting these standards, and is expected in spring 2011.
The partnership’s look at the research is yielding information about benefits not only to local environments and (potentially) global climate, but also to the people who live and work around greener landscapes—no surprise, when you consider that LEED-qualified buildings have already been shown to reduce rates of respiratory disease, allergies and asthma among building residents, leading to lower absenteeism and higher productivity. Including land development standards in greenbuild projects will increase these healthy-environment benefits. Positive social interaction is another benefit we can expect to find when landscapes are designed with well-being in mind. For example, the presence of tree and grass cover was tied to lower crime rates in a 2003 study of urban Chicago from the Journal of Arboriculture.
Tremendous advantages to energy and resource conservation are linked to sustainable sites as well. In developing its recommended practices, the Sustainable Sites Initiative has rethought many of the traditional uses of water, soils, plants and materials in site design. The practices it recommends instead are intended to restore our ecosystem’s ability to regulate itself, and in the process, reduce environmental damage.
In the past, landscape design has treated rainwater as a waste product, using large drainage systems that dumped water rapidly into creeks and rivers, causing flooding and erosion and severely reducing the absorption of groundwater needed to keep soil healthy. This rapid runoff is often contaminated by the weed killers and fertilizers used to feed and maintain installed landscapes, which has downstream effects on wildlife and recreation. On the other side of the equation, high-quality municipal drinking water—in shorter supply all the time—is used to irrigate gardens and lawns.
|JAJ Landscape Architectural Services of Houston has just completed LEED Certified Landscape Design and Installation for Walnut Bend Elementary, Houston Independent School District’s first LEED accredited elementary school. Environmentally friendly materials were used including native plants and recycled materials.|
How would Sustainable Sites address these issues of water waste and pollution? Instead of draining contaminated water away, landscape designers are encouraged to provide vegetated swales and filter strips to both clean and slow down water runoff. This slowed water can be harvested and used in place of municipal drinking water in irrigation systems, fountains and custodial applications. Water infiltration can be a built-in feature of landscape plans, by incorporating rain gardens and vegetated catchment areas to capture excess water.
The author is a U.S. Green Building Council LEED Accredited Professional and a member of the American Society of Landscape Architects.