sign in sign up
<<
Home , Landscape architecture, Landscape design, Sustainable design, Urban design

Potentials and Systems in Sustainable

Erica Ko

Editor Werner Lang Aurora McClain

csd Center for II-Strategies Site

2 2.2 Potentials and Systems in Sustainable

Potentials and Systems in Sustainable Landscape Design

Erica Ko

Based on a presentation by Ilse Frank

Figure 1: Five-acre retention and native prairie grasses filter and slowly release storm water run-off from adjacent residential development at Mueller Austin, serving an ecological function as well as an aesthetic amenity.

Sustainable Landscape Design quickly as possible using heavy urban infra- structure. Today, we are more likely to take Landscape will play an important advantage of the potential for reusing water role in structuring the of tomorrow by onsite for and gray water systems, for allowing landscape strategies to speak more providing , and for slowing storm water closely to shifting cultural paradigms. A de- flows and allowing infiltration to signed landscape has the ability to illuminate systems—all of which can inspire new forms the interactions between a ’s view of for integrating water into the built environ- its societal structure and its natural systems. ment. Water can be utilized in remarkable employs many of the variety of ways–-as a physical boundary, an same design techniques as architecture, but is ecological habitat, or even a waste filtration unique in how it deals with time as a function system. A large-scale example of an outmoded of design (Figure 2), its materials palette, and approach is the Rio Bravo/Rio Grande, which how form is made. Today, landscape architec- once meandered between the cities of El ture plays a leading role in Paso, and Ciudad Juarez, Mexico. This because of its ability to address ecological body of water was rechanneled and defined concerns associated with urban growth and with concrete banks to create a more clearly the . Sustainable ap- delineated geo-political boundary between proaches to landscape strive to create places the two countries. While this intervention has of value and meaning while also respecting maximized the river’s potent physical and vi- and acknowledging the important functions sual ability to demarcate distinct spaces, it has that nature performs. Sustainable landscape also divorced the river from its unique capacity design combines aesthetic and psychological to engage a landscape through the ephemeral advantages while tapping into the enormous ebb and flow of erosion and deposition, and ecological and functional potential of living has removed the habitat potential of a large systems. swath of land. Water is a critical resource for cities in the 21st century, but we can no longer Shaping (the role of) water rely on concrete and heavy-handed engineer- ing to shape its flow. These techniques cause Water is a powerful element which has the critical problems for , ability to shape the organization of a site. erosion, and maintaining native . Attitudes toward water as a site element have We must integrate water into our site design, changed over the course of the 20th century. rather than pushing it aside, to generate new Water is no longer moved across a site as forms for living in the 21st century.

3 II-Strategies Site

Figure 2: as a catalyst for new development patterns for the of Quito through urban tree production. Parque del Lago Competition Design by Dean Almy, Ilse Frank, and Jason Sowell.

Water may act as a defining site feature dition permits the use of the water’s edge and ures 2 and 4), by providing an area of natural through various “edge conditions” where a encourages occupants to be in close interac- filtration and helping to break down some of transition occurs between water and land. tion with nature in an urban context where that the harmful substances in the run-off before Soil erosion is an important concern when is especially rare and valuable. the water drains into a stream. considering the interaction of water and land, and various strategies can be used to address Another type of edge condition is a ripar- Consequences of the built environment this issue. The or slope of the land may ian buffer, which is the strip of land adjacent be manipulated to protect the edge, and subtle to a stream where the vegetation is closely Rapid sheet flow across impermeable surfaces variations can be designed with this goal in influenced by the presence of water. A buffer at during a storm event and accumulation of mind. Edge conditions have various options to the edge of a creek or river can protect against sediments and pollution from roadways in consider in their design—whether to allow or soil erosion, provide habitat and food for native the storm surge are the two largest problems discourage human engagement with a water species, mitigate non-point source pollu- affecting the built environment’s impact upon body, to develop certain , or to direct tion, and slow surges. Depend- water quality. Water flows more quickly across the flow of water. In Park, ing on their width, buffers can serve multiple impermeable surfaces such as and which extends along the East River in Brook- functions, with increasing possibilities where paved areas, than it does across impermeable lyn, New York, some edges were treated in a greater width is available for the buffer area. A surfaces that allow water to infiltrate. The most rough and naturalized manner, with grass and narrow buffer can protect against erosion and critical volume of water in a storm event, with soil ending in a buffer of large irregular rocks supply an important source in the food web, regard to water quality, is the “first flush,” which toward the water. Since public use was also while larger buffers can serve additional func- contains the majority of the pollutants and a primary component of this program, some tions such as providing habitat, control, sediments which are washed across imperme- other points received a different treatment, with and sediment control, etc. Buffers can also able areas. As the water runs over these sur- large stone slabs terracing down to provide play an important role in managing non-point faces, it collects impurities and toxic elements seating in close proximity to the river. This con- source pollution, such as run-off (Fig- left by pollution from or other sources.

4 2.2 Potentials and Systems in Sustainable Landscape Design

Collecting and slowing this first run-off from a Bioswales retention and detention basins provide an storm event, thus managing pollutants onsite opportunity for stormwater to recharge the as much as possible, is the most important Bioswales are shallowly sloped channels filled groundwater onsite, provide irrigation, and to task that landscape design can undertake with with vegetation, or rocks that have supply an amenity on site, whether functional regard to water. Water cannot penetrate imper- been graded to accept run-off and move it or aesthetic. meable surfaces and thus cannot be filtered slowly over their surfaces. They are designed and absorbed by and soil. In addition, to maximize the amount of time the water Sediment/infiltration basins the flow of water is not slowed by the absorp- spends in the swale, allowing contaminants tion process and therefore places a greater and silt to be captured and slowing the flow Sediment or infiltration basins also allow water burden on our storm sewer systems. Cities of water to larger bodies. They are commonly to percolate slowly into the ground and are with combined sewer systems are at high used around lots and roadways, commonly used in urban conditions as land- , since the overflow of combined sewer where run-off tends to be highly polluted. As a scape elements. They can take a variety of systems can cause raw sewage to end up in physical intervention, bioswales can engage forms and can make use of vegetation which natural waterways. When run-off drains rapidly seasonal changes through vegetation, make is able to handle a wide range of moisture in into bodies of water, it causes higher levels of evident the natural processes of vegetation order to survive dry periods as well as times toxicity, erosion problems, and the possibility of interacting with water, and provide a new edge of inundation. A second kind of sediment/ storm surges and flooding conditions. We must condition between and buildings. infiltration basin (Figure 3) can be contained design the path of the water, especially the sub-grade which sends storm water for cleans- “first flush,” to mitigate the problems of erosion, Retention and Detention Basins ing through a filtration system composed of non-point source pollution, and overburdening varying grades of fines in a contained area. our municipal storm sewer systems. Retention basins (Figure 1) serve a similar This system can be of particular benefit to purpose but hold water in pools, whose water more urbanized areas where open is Retention and filtration strategies levels fluctuate with the of rainfall versus at a premium, and vegetative water-cleansing the rate of absorption. Retention basins can techniques are not feasible. Through all of Allowing the landscape to filter and absorb take on the form of a vegetated pond, similar these retention methods, rainwater can be water naturally is a key strategy for sustainable to a wetland condition, which can engage pub- captured and reused with a pumping system landscapes. Some fundamental approaches lic space as a respite from the day to day ur- for irrigation, thereby greatly reducing overall include bioswales, rain , retention ban built environment. At further extremes, the water consumption. basins, detention basins, and sediment/infiltra- form of a retention basin can take on a format tion basins. In addition to providing ecological that engages pools in a series of functions that Rain gardens benefits, these systems also supply landscape slow water and filter different sediments—with amenities that are of significant value to the the potential to alleviate a new development’s Another landscape amenity that also serves users of the site. The addition of functional reliance on . A second basin a functional need is the rain . It is es- vegetative elements to a site can provide condition, the detention basin, acts similarly sentially a more specific type of bioswale or aesthetic value and the psychological benefits but does not necessarily always contain water. sediment/infiltration basin. Rain gardens are of viewing natural elements, through inviting Its main purpose is to capture water during planted depressions located in areas where native species such as birds and insects to high levels of rainfall, when any retention rainwater drains from an impermeable source be involved in a user’s daily interaction with a basins may already be exceeding their holding such as downspout on buildings or a parking space. capacity, thus slowing its flow and allowing it lot. They can be used at points where a shift to absorb slowly into the ground. Detention between pervious and impervious occurs. basins may be heavily vegetated and during Rain gardens create an attractive alternative drier periods can serve multiple functions to the typical drain set into a depression in the as sports fields or open green spaces. Both asphalt below a downspout.

Figure 3: Subsurface STORMChamber system maximizes Figure 4: Pervious concrete paving promotes on-site retention Figure 5: Selective mowing practices promote habitat potential pollutant removal from stormwater on a minimal footprint size. of water and grounwater recharge with a variety of finishes. as well as carbon sequestration.

5 II-Strategies Site

Alternative surface treatments

Pervious concrete paving (Figure 4) and porous asphalt are also options for managing stormwater run-off. This provides a smooth, drivable surface that while still allowing water to penetrate through it and be absorbed into the ground. Pervious paving can take many forms, from pre-cast pavers or bricks set in sand, to a concrete mix that preserves pockets of air to allow infiltration. It should be noted that pervious pavement is not suitable for all situations, since it needs to be regularly maintained and vacuumed out so that sediment will not clog the. Pervious paving can take many forms, from pre-cast pavers or bricks set in sand, to a concrete mix that preserves pockets of air to allow infiltration. It should be noted that pervious pavement is not suitable for all situations, since it needs to be regularly maintained and vacuumed out so that Figure 6: Intensive terraces at terrace edges of the Gulbenkian Museum in Lisbon, Portugal. sediment will not clog the pores of the asphalt. This may also limit its use in colder climates where roads are salted in the winter to prevent snow accumulation.

A second, inexpensive alternative surface treatment is selective mowing of grasses (Fig- ure 5). By planting native grasses and allowing them to grow tall, animal habitat and diversity is restored and a greater amount of carbon sequestration function is restored.

Green roofs and their benefits

Green roofs are perhaps the most iconic sys- tem utilized in sustainable landscapes. There are two types of green roofs–extensive and intensive. Extensive green roofs are typically composed of a mat of sedums or grasses with a minimum soil depth of three inches (Figure 7). They are typically self-sustaining, requiring very little maintenance; however in more arid environments, such as Texas, some irriga- tion may be required to supplement in times of . Intensive green roofs (Figure 6) Figure 7: Extensive green roof of native vegetation viewed from inside the Starbucks in Circle C Ranch Development in Austin, TX. require a greater soil depth and can support larger plants such as trees. They typically require a fairly high level of maintenance and regular irrigation but are commonly designed to also function as and withstand those associated live load conditions.

Like the previously discussed infiltration and drainage systems, green roofs also capture, slow, and filter rainwater. The soil and plants bind and can capture up to 95% of the , copper and particulates that fall on them. Besides creating a perme- able layer that reduces the flow of rainwater and moderates runoff temperatures that could harm aquatic life, green roofs provide addi- tional insulation to the ’s roof, reducing the energy needed to heat and cool the interior Figure 8: Flexible installation of green roofs is possible with pre-grown tray panels set upon waterproofing and drainage mats.

6 2.2 Potentials and Systems in Sustainable Landscape Design

spaces. This added mass also serves as an which can be mental types of green walls - acoustic buffer. When used in cities, green green facades and living walls. Green facades roofs can have a significant impact on reducing consist of climbing plants which are trained the effect through absorbing to grow over certain portions of the wall and solar radiation and releasing the heat through are rooted either at the bottom of the structure evapotranspiration, which cools the building or in intermediary planters. Living walls (also and the local air. In addition, the layer of plants known as biowalls) are made up of modular protects the roof from UV deterioration, dou- pregrown panels, similar to those used for bling its lifespan. The plants absorb gaseous green roofs, which can be installed onto a pollutants through their leaves and filter dust vertical surface in both exterior and interior and dirt particles out of the air, thus improv- applications. These wall systems can have ing air quality for the building’s occupants. benefits similar to those of green roofs, though Ten square feet of leaf surface can trap five generally to a lesser degree. pounds of dirt from the air every year. Sixteen square feet of uncut grass can provide a one Speculations and potentials year supply of oxygen for one person. Beyond these numerous environmental advantages, The incorporation of new greenspaces into green roofs also provide immense aesthetic urban environments can be accomplished value by replacing views of typical black, tar through early decision making for allocation roofs with the beauty, color and texture of of functional open space and the re-use of plantings. derelict for new purposes (Figure 11) as well as finding new potential in existing Green walls urban spaces (Figure 9).

A is a vertical surface which is The greater sum of all new green space in covered in material. There are two fun- a city can have a significant impact upon damental types of green walls - green facades its future. Balmori Associates undertook an and living walls. Green facades consist of exploration of the potential for green roofs in climbing plants which are trained to grow over the dense urban context of . certain portions of the wall and are rooted Looking specifically at a particular neighbor- either at the bottom of the structure or in hood, Long Island City, in Queens, they posed intermediary planters. Living walls (also known the question – What if every building had a as biowalls) are made up of modular pregrown green roof? They discovered that the added Figure 9: 2009 PARK(ing) Day temporary installation, Austin, panels, similar to those used for green roofs, green area would be equivalent to the area of TX.

Figure 10: Hundertwasser’s “man tenant” and “tree tenant”. Figure 11: Re-use of abandoned infrastructure as . The Highline in New York City by Field Operations.

7 II-Strategies Site

Prospect Park, one of the most significant park Notes Biography spaces in Brooklyn. In addition, 55% of the ex- isting impervious cover would be transformed 1. + “6 Things Ilse Frank holds a Bachelor of Architecture into pervious green space. These changes You Need to Know About Green Walls” http:// from the University of Texas at Austin and a would lead to significant benefits both at the www.bdcnetwork.com/article/CA6459410.html Master of Landscape Architecture and Master scale of the neighborhood and at the larger of City from the University of Penn- scale of the city in ameliorating the urban heat 2. NYC Department of Design and Construc- sylvania’s School of Design. island effect, cleaning air, and regulating water. tion “High Performance Building Guidelines” and “High Performance Infrastructure Guide- At Penn, she was research assistant to Dr. Another more speculative approach to the lines” http://www.nyc.gov/html/ddc/html/design/ Susan Wachter, Wharton Professor of Real integration of landscape and building appears sustainable_home.shtml Estate & Finance and co-director of the Penn in the work of the Austrian artist, Friedensreich Institute for Urban Research, focusing on Hundertwasser. His whimsical sketches and future development patterns and natural re- projects place trees as dominant elements, Figures sources of the Everglades and Biscayne Bay, bursting out of windows and even acting in and around Miami-Dade County. as “tenants” (Figure 10) within buildings. Figure 1: Courtesy of Ilse Frank. Hundertwasser’s work suggests a significant Ms. Frank’s interdisciplinary experience focus- rethinking of the secondary role we tend to Figure 2: Courtesy of Dean Akmy, Ilse Frank, es on and landscape architec- assign to landscape and nature and envisions and Jason Sowell. ture. Ms. Frank has practiced in design what such a reevaluation could inspire. in New York, Philadelphia, and The Nether- Figures 3-9: Courtesy of Ilse Frank lands. In practice, Ms. Frank has joined with Conclusion collaborative teams for winning, international Figure 10: http://voluntarysimplicityinaction. competition entries for urban-scale projects in Sustainable landscape design serves an blogspot.com/ , , and Korea. important role in mediating the significant environmental damage caused by common Figure 11:Courtesy of Ilse Frank building practices. It aims to create places that can link into ecological systems instead of de- stroying them. Landscape is also recognized Recommended Reading for its profound psychological and aesthetic benefits- helping us to understand our place in Corner, James (ed.). Recovering Landscape: the world. The intrinsic value of landscape can Essays on Contemporary Landscape Architec- be rediscovered and brought to the forefront ture. New York: Princeton Architectural Press, of design and the built environment. Sustain- 1999. able landscapes investigate how we reflect ourselves in landscape and how landscape in Shepheard, Paul. What is Architecture? An Es- turn reflects us. say of Landscapes, Buildings, and . Cambridge: The MIT Press, 1994.

8 2.2 Potentials and Systems in Sustainable Landscape Design

9