Urban Sustainability Enhanced Through Landscape Architecture
By Thomas R. Tavella, FASLA
Many architecture and engineering firms have faced declining workloads and reduced workforces in recent years. But landscape architecture firms appear to be doing well and even growing.
The reasons why? For starters, landscape architects are playing a more significant role in municipal projects thanks to Americans becoming more health conscious. This means they are planning and designing more running and walking spaces for communities.
Meanwhile, there is the impact of the ever-popular “green” movement, which has led to more building owners and operators seeking LEED (Leadership in Energy & Environmental Design) Certification from the U.S. Green Building Council—a goal landscape architects can help achieve.
The interest in sustainable landscape architecture design helped spur the Sustainable Sites Initiative. Launched by the American Society of Landscape Architects, and in partnership with the Lady Bird Johnson Wildflower Center University of Texas at Austin and the United States Botanical Garden, the Sustainable Sites Initiative is an interdisciplinary effort to create voluntary national guidelines and rating system for sustainable land design, construction, and maintenance practices for landscapes of all types with or without buildings.
This article explores ways that landscape architectures are not only “greening” up properties in the more literal sense, but “greening” them up through the implementation of sustainable technologies and approaches.
Filtering out pollutants and sediments
Urban development such as streets and parking lots diminish the amount of open ground available for the absorption of stormwater. This means pollutants and sediments tend to accumulate before ultimately being released into local water supplies.
Pervious pavement is one way to combat this problem. Pervious pavement helps filter out the automobile oil, grease, and sediment that frequently accumulates in parking lots and streets, as well as other areas where vehicles are frequently found. After the stormwater is filtered, it is absorbed back into the natural aquifers in the earth. Also, thanks to this filtration process, the stormwater is released at a much slower rate than in a typical drainage infrastructure system. This ensures that a municipality’s sewer system will not be overwhelmed.
Engineers and planners are sometimes hesitant to use pervious pavements in cold weather areas, fearing that they could freeze over in icy weather. However, that line of thought is changing, as many projects are showing that pervious pavement is actually useful in Northern areas since their design keeps the ground warmer than traditionally paved roadways.
Cleaning and slowing down stormwater runoff
Landscape architects are also promoting sustainability in urban areas through the use of “green” infrastructure techniques such as biofiltration swales. Comprised of grasses and durable plants, biofiltration swales are vegetated areas that remove pollutants from stormwater runoff as it flows
through the vegetation. The plants featured in a biofiltration swale can withstand the most extreme conditions, including extensive rain and severe heat.
Biofiltration swales are designed specifically to treat stormwater runoff for a specified water quality volume. The swales clean the runoff by naturally filtering out contaminants, which prevents polluted stormwater from infiltrating local streams and wetlands. Some plants can even filter heavy metals from water, which is particularly useful in industrial areas. The stormwater is also slowed down before it’s safely distributed to sewers for disposal. This helps reduce erosion and flooding.
The many benefits of using vegetation
Similarly, landscape architects are using vegetation such as street trees and shrubs to improve air quality, particularly during excessively hot weather. Air temperatures can be up to 20 degrees cooler beneath trees than in surrounding areas, an important health benefit for people who live in areas of extreme heat. Also, the leaves from various species of trees and shrubs can help improve air quality by removing dust and other particulates, as well as absorbing carbon dioxide.
Another—and particularly more innovative—use of vegetation involves the “green” roof (also known as the living roof). Comprised of trees, shrubs, low-growth grasses, and sedums, “green” roofs can cap just about any structure in a community. The vegetation on a “green” roof is drought tolerant, weed resistant, can withstand extreme temperatures, and do not need mowing.
One of the main purposes of a “green” roof is to control stormwater runoff. Rainwater can be collected, filtered, and stored in a cistern. The water is then utilized in irrigation and wash-down systems. Also, drainage systems can help control the amount of stormwater being released into a community’s sewer system.
A “green” roof can also help reduce urban heat island effect, a phenomenon in which a metropolitan area is significantly warmer than its surrounding rural areas. They are also particularly useful in eliminating the risk of salt and other corrosives being introduced to a structure’s roof, improving outdoor air quality since the vegetation can trap dust and absorb carbon dioxide, and increasing biodiversity by creating a habitat for insects, birds, and butterflies.
Sustainability: A Cornerstone
More and more landscape architects are incorporating “green” technologies and approaches in projects. And the result is properties that not only better serve the public, but are better for the environment. Sustainability has truly become one of the cornerstones of today’s landscape architecture profession.
Thomas R. Tavella, FASLA. is director of design for Fuss & O’Neill’s Landscape Architecture Studio and president-elect of the American Society of Landscape Architects. Manchester, Conn.-based Fuss & O’Neill is ranked among the top 200 environmental firms and top 500 design firms in the United States. Tavella can be reached at TTavella@fando.com.