Landscapes can have a powerful impact on the environment
The green-building 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 (quickly) about what elements count most toward a building's greenness. The metrics provided in the U.S. Green Building Council's voluntary LEED standards have largely defined the goals of the building industry's greenward turn. But, in the USGBC'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 impact on the environment. In recent years, those impacts—both positive and negative—have been under study by scientists and engineers around the world. The Washington, D.C.-based American Society of Landscape Architects (ASLA), together with the Austin, TX-based Lady Bird Johnson Wildflower Center and the U.S. Botanic Garden in Washington, D.C., 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 green-building umbrella.
Called the Sustainable Sites Initiative, this interdisciplinary coalition is addressing land development and management practices 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) the global climate, but also to the people who live and work around greener landscapes. Including land-development standards in green-building 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 by Arboriculture & Urban Forestry (formerly the Journal of Arboriculture).
Tremendous advantages in terms of 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 are intended to restore our ecosystem's ability to regulate itself and, in the process, reduce environmental damage. (All of these actions will lead to cost savings for building owners, too.)
Look at water: In the past, landscape design treated rainwater as a waste product, using large drainage systems that rapidly dumped water 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. And, on the other side of the equation, high-quality municipal drinking water - in shorter supply all the time—is used to irrigate these human-altered gardens and lawns.
How would the Sustainable Sites Initiative address the 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. And, water infiltration—to increase groundwater recharge, irrigate vegetation, and reduce soil erosion—can be a built-in feature of landscape plans by incorporating rain gardens and vegetated catchment areas to capture excess water.
The recommendations briefly outlined in this article are taken from the Sustainable Sites Initiative's Preliminary Report on Standards and Guidelines, released in November 2007. It's a strong start, and landscape architects will be watching its progress closely; we have been encouraged to comment and contribute what we have learned in the field. And, as the evidence in favor of more efficient sites mounts, we anticipate raising the green bar higher, starting from the ground up.
Jo Ann Jarreau, president at Houston-based JAJ Landscape Architectural Services, is a LEED Accredited Professional and a member of the American Society of Landscape Architects (ASLA).