Design Options for Greening Urban Environments

Green infrastructure versus grey infrastructure
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Sponsored by Bison Innovative Products, DeepRoot Green Infrastructure, greenscreen®, Invisible Structures, Inc., and IRONSMITH, INC
Elena M. Pascarella, PLA, ASLA
The Visionaire, NYC

Modular decking on the green roof of the Visionaire Condominium in New York City meets LEED credit in Materials and Resources.

Photo courtesy of Bison Innovative Products

The Visionaire is New York City’s first LEED Platinum-certified condominium project. This project used a modular decking system for their roof patio and as access to their green roof plantings. The Visionaire features a green roof covering 70 percent of the rooftop. The decks on the Visionaire used FSC Massaranduba Tiles and thus qualified for LEED credits. The pedestals have recycled content and thus provided a credit through Materials and Resources.

This project also qualified for a tax credit through a 2008 New York City bill (A.11226) that allowed building owners in New York City who install green rooftops to receive a property tax credit. Under this law, building owners in New York City who install green roofs on at least 50 percent of available rooftop space can apply for a one-year property tax credit of up to $100,000.

These modular decking systems protect and extend the life of costly roofing and waterproofing systems, and reduce heat and cold penetration into the building so they provide a means of reducing energy and the related costs.

 

Sustainable green infrastructure begins with providing appropriate conditions for the growth and maintenance of vegetation. It is essential that planting areas provide sufficient room for plant growth and provide a planting medium that is loose, friable, and containing sufficient organic matter so that soil can retain porosity for air circulation and water absorption. Sustainable urban green space can be attained through a number of innovations that provide plantable soils, pervious and flexible pavement systems, urban tree protection, vertical planting frames, and flexible surfaces for roof insulation.

Recapturing and Enhancing Urban Green Space

According to the U.S. Forest Service Urban and Community Forestry Report, June 2010, Sustaining America's Urban Trees and Forests: Forests on the Edge, “...tree cover in urban areas of the conterminous United States is estimated at 35.1 percent (20.9 million ac). As urban areas expand, the amount of urban forest will increase and urban forests will become increasingly critical to sustaining environmental quality and human well-being in urban areas. Careful planning and management will be crucial to maintain and enhance urban forest benefits.”

Mature urban forests provide innumerable benefits to a community. They reduce and slow stormwater runoff; serve as habitat for birds, mammals, and insects; reduce energy consumption; mitigate extreme temperature fluctuations; reduce heat island effects; enhance air quality; remediate contaminated soils; help to moderate climate change; and provide attractive, healthy living environments for people. However, urban trees rarely live to their mature age due to the challenges of survival in the urban environment. These challenges include compacted soils, poor hydrology, and constraints to trunk expansion and root growth from urban infrastructure.

Providing Better Soil Structure for Urban Forests

Structural soils are one means of providing urban trees with the medium essential to proper growth and sustainable long-term viability. A study conducted at the Urban Horticulture Institute at Cornell University (N. Bassuck, J. Grabosky, P. Trowbridge, J. Urban) introduced structural soils as a medium for integrating trees into pavement. Structural soils are designed to meet or exceed pavement design standards so that pavement compaction levels can be achieved while the soil remains sufficiently “porous” for root growth and stormwater penetration. Structural soils also provide a continuous base course under pavements for tree root growth.

 

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Originally published in Architectural Record
Originally published in November 2012

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