Environment: The Rebuilding and Greening of the World Trade Center Site

“While creating exciting contemporary architecture is about icons, it is also about high performance and environmental sustainability at every level. It is an endeavor that should employ the greatest minds of our generation, which are capable of thinking across categories and fields at the interface of culture, technology, and urban life to build a satisfying relationship among these elements.”

— Principles of Rebuilding Lower Manhattan February 2002, New York New Visions

Out of the September 11 tragedy has come a rare opportunity to redevelop one of the world’s most vital and valuable urban spaces. As the world watches the redevelopment of the World Trade Center site unfold, it has become clear that the development process will not only create new icons in the Manhattan skyline, but also set a national and international precedent in design and construction techniques for future large urban development projects. Specifically, the agencies involved in the redevelopment are working to create healthier, more efficient buildings in Lower Manhattan — an approach commonly known as “green building.” While not a new concept, green building has reached new heights in popularity over the past few years. The planned utilization of green building for the redevelopment of Lower Manhattan may help propel this building model from a growing, but still small, segment of the market to a mainstream way of doing business. 

What is Green Building?

Conventional construction and building operation, as it has developed in the United States and throughout the world, often damages the surrounding environment and harms occupant health. Such impacts include the production of solid construction wastes, emission of greenhouse gases, unhealthy air inside buildings, and the consumption of valuable non-renewable resources (such as water and energy). Green building, described in the trade publication Building Green as “a collection of land-use, building design, and construction strategies” that has only begun to mature in the last decade, can diminish — even, in some cases, reverse — many of these negative environmental effects. Through better understanding of natural systems, advances in technology, and reductions in costs, green building is gradually becoming an important aspect of how buildings are built and operated in America, with particularly strong developments in the last few years.

Green building’s benefits fall chiefly into three areas: reduced energy consumption, protection of ecosystems, and improved health for building occupants. First, conventional buildings require vast amounts of energy — indeed, 40% of energy consumption and two-thirds of electricity consumption in the world results from the construction and operation of buildings. Conventional buildings meet these energy needs by burning fossil fuels directly to produce heat, or indirectly by using conventional electricity, which in turn is provided through the burning of fossil fuels. The combustion of fossil fuels emits greenhouse gases into the air, which contribute to global warming.

Green building reduces energy consumption by increasing the energy efficiency of buildings and using renewable energy resources, such as the sun. Green buildings often have insulation systems, known as “tight envelopes”, that prevent mechanically cooled or warmed air from escaping. In addition, facing buildings in the appropriate direction can maximize the use of the sun for lighting, while incorporating glazed windows helps ensure that the extra sun exposure does not require additional cooling of the buildings. “Green roofs“ — coverings that include insulation, waterproofing, soil, and native low-maintenance plants — can help keep buildings cool in the summer and warm in the winter, thereby reducing energy costs year round. These roofs have proved effective in urban environments throughout the country, such as Chicago’s City Hall. The use of energy-efficient appliances and lighting can also contribute to reduced energy consumption.

Alternative sources of energy can help meet the energy demand of buildings, without requiring the combustion of fossil fuels and subsequent emission of greenhouse gases. Solar panels along outside walls — such as those on 4 Times Square in New York City — or on roofs can generate electricity or heat water using the energy from the sun. In addition, recent technological advances mean that windmills and wind-turbinescan generate significant local supplies of energy, while heat pumps in the ground, such as those used in the 1400 on 5th residential development in Harlem, can contribute to energy savings.

Alternative energy sources and increased energy efficiency do more than reduce energy costs; they can also improve public health. In the summer, major American urban areas are warmer than outlying rural areas by as much as 10 degrees. This heat island effect is a result of the vast acreage of asphalt paving and dark roof coverings that absorb heat and then slowly release the heat back into the environment — thereby raising the temperature. The heat island effect also increases the intensity of the smog produced by vehicular exhaust, a major cause of degraded air quality and related illnesses (such as asthma). Reducing the heat island effect through the use of green roofs, landscaping, and heat reflecting building materials and colors reduce cooling costs for the green building and the surrounding area. And by helping to reduce smog, green buildings can reduce the occurrence of certain respiratory ailments.

Second, conventional buildings harm natural ecosystems by degrading water quality. For example, many conventional buildings allow storm water run-off from roofs and other paved surfaces to escape into bodies of water. Green building strategies such as site landscaping, permeable pavement materials, and the aforementioned roof vegetation can absorb and hold water during a storm to lessen run-off from pavement into the waterways while also naturally filtering the water. Through water conservation measures, such as the installation of water-efficient plumbing fixtures and appliances, green building reduces the demand for water from already strained reservoirs. Rainwater and “graywater” — used water from sinks and showers — can be collected and recycled for landscape irrigation and toilet flushing to further reduce water consumption. 

Green buildings are also economical with building materials where conventional construction is not. When feasible, they use fewer materials or incorporate recycled materials, conserving energy and saving money compared to conventional building components. Examples include insulators made of cellulose insulation, recycled glass tiles, and recycled fixtures. In instances where recycled and alternative materials are not feasible, designers of green buildings procure environmentally responsible supplies such as certified sustainable harvested wood or local hardwoods, instead of the tropical woods and other ecologically harmful materials that conventional buildings use. These substitutions can cut down on both financial and environmental costs. In the selection of materials, consideration of the total impact of the products, which includes looking at the use of resources and creation of pollution throughout the mining, production, distribution, and disposal phases, is key.

Finally, green buildings improve occupant health. In conventional buildings, many toxic materials, such as polyvinyl chloride, hydro-chlorofluorocarbons, and volatile organic compounds (VOCs), are used in building materials like solvent-based finishers, adhesives, carpeting, and particleboard. These materials, which release fumes into the air during use, play a major role in creating “sick building syndrome.” According to the World Health Organization, 20% of white-collar workers in the U.S. experience sick building or related syndromes caused by VOCs, combustion gases, carbon dioxide levels, mildew, mold, and tobacco smoke. Green buildings incorporate materials that do not produce toxic gases during use. In addition, green designers integrate effective ventilation systems into buildings that cycle air between the outside and inside to reduce sick building syndrome. Operable windows can also help improve the ventilation of buildings and the comfort of their occupants.

The success of green building over the long term will largely depend on its cost-effectiveness. Increasingly, green building produces significant cost savings. Green building techniques, over the long run, reduce energy costs, maintenance needs, and material replacement costs, which offset initial costs that are sometimes greater. Green buildings result in increased worker productivity due to the healthier environment they create, producing bottom line benefits over the long term. According to David Gottfried in The Economics of Green Building, only 2% of building costs occur during the construction phase of buildings, 6% of costs come from operation and maintenance and an immense 92% of costs come from payroll expenses. An initial “green” investment in constructing a building can garner a significant return in terms of the long term health of the building’s occupants.

While the initial investment required to build a green building can be substantial, government subsidies help. For example, the EPA’s EnergyStar program offers a rebate with the purchase of EnergyStar rated energy-efficient appliances. New York has created the first state-level green building tax credit and has allocated $25 million to this program. Still, more financial incentives are necessary to make these technologies competitive in the short run, since the developers who incur the higher short term costs are not necessarily the tenants who will benefit from the long term savings. Even so, green building now offers a fairly practical, increasingly cost-effective method of conserving energy, reducing environmental impact, and improving occupant health. When green building strategies are well-integrated into the building design early in the development process, it is often possible to create a green building without higher cost.

Building Green: The WTC Site Consensus

The drive to incorporate green building techniques into World Trade Center site redevelopment has come from three sources: the public at large, community groups, and government entities. This strong consensus around environmentally sensitive development of Lower Manhattan means that green building will likely play a significant role in any redevelopment plan.

The planning process for the redevelopment of the WTC site has boasted some of the most successful democratic involvement of any development planning process in American history. Last July, the non-profit Civic Alliance to Rebuild Downtown New York organized Listening to the City, a town meeting about plans for the site. Over 5000 people participated in small group discussions on the future of Lower Manhattan, both in person and online. The conversations addressed the expected pivotal topics: the “what” and “where” of development, including recreating the skyline and designing an inspiring memorial. Along with discussion of these topics, however, emerged a surprisingly loud voice in support of “how” development should occur in order to protect the environment of downtown Manhattan. Specifically, participants highlighted the importance of incorporating ecologically sensitive building technologies into the design and construction of future development. The Civic Alliance reported that the use of environmentally-conscious and energy-efficient techniques in rebuilding was one of Listening to the City’s six most prominent themes. In an online voting system, 45% felt that focusing on the environment while rebuilding was “very important.”

This public concern has been buttressed by demand for green building among New York’s academic and non-profit community. In early October 2001, the Pratt Institute, a renowned New York design school, published Principles of New York’s Recovery, which suggested that “we need to collectively advocate for the implementation of Green Building principles in the redevelopment of Lower Manhattan.” The center’s insistence on green building came from its recognition that the benefits of green building accrue to not just the site itself but also to the city and region as a whole. Soon after, over 400 individuals, including representatives of the American Institute of Architects, the American Planning Association, and the Regional Plan Association, created New Visions New York, which published Principles of Rebuilding Lower Manhattan. The February 2002 report suggested that the redevelopment plans for the WTC should set new standards for environmental sustainability while requiring decreased life-cycle costs and energy use. Local and state government are advocating for green building as well. Even before September 11, both the city and the state promoted green building. The city’s Department of Design and Construction (DDC) wrote the High Performance Building Guidelines to outline green building strategies and techniques for the city’s own building projects, such as libraries and courthouses. In one of the most important residential green building successes to date, the quasi-public Battery Park City Authority created guidelines for the development of residences neighboring the World Trade Center site that required environmental sustainability in both the construction and operation of new buildings.

New York state has been a leader in the green building movement for years. As mentioned above, the New York State Energy Research Development Authority (NYSERDA) offers tax credits for green building. The tax law is “intended to encourage building owners and developers to design, construct and operate buildings that are energy efficient, utilize recycled materials, provide clean air, and incorporate renewable and energy efficient power generation.” In November, the US Green Building Council awarded New York Governor George Pataki the first ever Sacred Tree award for his leadership in the green building movement.

A new city-state joint agency that oversees the revitalization of the WTC site and the surrounding area is following the the green building precedents set by the city and state. Former New York City Mayor Rudy Giuliani and Governor Pataki established the Lower Manhattan Development Corporation (LMDC) to revitalize Lower Manhattan south of Houston Street. Among its guiding principles, LMDC includes the promotion of “sustainability and excellence in design for environmentally sensitive development.” In its search for innovative designs for the World Trade Center site, LMDC, working with New York New Visions, states it is looking for firms or individuals that have a history of superlative design and site planning, including experience with “projects that exhibit extraordinary design excellence with an emphasis on environmental consciousness and sustainability to create long-lasting economic and social value.”

The support of green building from the public, community organizations, and, especially, the government, has already led to action. Governor Pataki’s administration has agreed to require the construction equipment at the World Trade Center site to adhere to strict air pollution controls. Such controls will prevent the aggravation of air quality problems downtown. This commitment is crucial since it will take an estimated six to ten years to rebuild on the World Trade Center site — no doubt one of the largest urban reconstruction projects in the U.S.

The consensus behind prioritizing environmental protection in the design and rebuilding of the WTC has created an opportunity for New York to prove its commitment to the environment and the public health of its residents. By doing so, the city will cement its role as a leader in the use of new technology and sustainable development, creating a model for future large urban redevelopment projects. The WTC site will demonstrate, more than any previous green building project, that it is possible to create a beautiful and functional space that also protects water resources, minimizes waste production, and reduces air pollution.

Hugh Eastwood, a LMDC planner, sums up the sentiment on green building that has emerged from the redevelopment process. “Lower Manhattan will be a model of a 21st century sustainable downtown,” Eastwood says. “If we do not do that, we will have failed.”