jun 07 | Urbanland

Signing sustainable buildings

by Gordon Gill

As everything within the built and natural environment is connected, so a building's design should stem from an understanding of its role within that context---locally, regionally and globally.

Urban areas are experiencing a renaissance, reestablishing themselves as facilitators of upward migration in the search for an improved livelihood. The densification of cities is evident worldwide---in India, the Middle East, Latin America, and North America. In China, more than 12 million people are expected to move into urban areas every year between now and 2030.

In 2015, 3.9 billion people worldwide will be living in cities and over 40 percent will be living in cities of more than 1 million people. Estimates suggest that by then, 375 million people will be living in 23 megacities---urban areas of over 10 million people---including Tokyo, with 26 million; Mumbai, 26 million; Lagos, 23 million; Dhaka, 21 million; and São Paulo, 20 million.

In response, cities across the globe are enhancing their infrastructures, resulting in a development boom so concentrated that it has been termed a 'Second Industrial Revolution.' At this critical juncture in the evolution of the urban area, cities have a unique opportunity to assert themselves as centers of healthy living.

Inherently, cities are more sustainable than suburban areas because they accommodate more people on less land. An urban residential high-rise tower can house 240 units on a fraction of a city block, for example, while the space required for a suburban development with the same number of units (on 1/8 acre lots) is about 30 acres (12 ha), not including roadway infrastructure. In addition, one of the byproducts of urban development is the ability to preserve rural land for agricultural development. The loss of farmland to suburban developments is profound: in the United States, land is claimed at about 1.2 million acres (486,000 ha) per year. At the height of Phoenix, Arizona's growth, the rate of sprawl was about one acre (0.4 ha) converted every hour.

Land consumption is not the only downside to sprawl. The time spent commuting from residence to work place has negative ramifications as well. A commuter living an hour's drive from work annually spends the equivalent of 12 workweeks or 500 hours in a car. According to a 2007 Department of Transportation report, traffic delays caused the United States to lose 3.7 billion hours and 2.3 billion gallons of fuel in 2003.

In contrast, city dwellers are far more likely to ride mass transit, bike, or walk to their place of work. An April 2007 study conducted by New York City's Office of Long-Term Planning and Sustainability noted that per-capita carbon emissions of New Yorkers less than one-third those of the average American, due, in part, to more efficient, shorter commutes in New York City. Yet, it would be irresponsible for cities to simply be satisfied with being more sustainable than their suburban neighbors. Despite generating less carbon dioxide emissions per capita---largely due to more sustainable modes of transit---cities are still responsible for nearly 80 percent of the carbon emissions worldwide. However, the major environmental offenders in urban areas are not automobiles, but buildings.

In the United States, buildings account for roughly 40 percent of carbon emissions; in New York City, the number soars to nearly 80 percent. Only the creation of sustainable communities will reverse this trend. They key to creating sustainable cities lies in better planning and design- and a holistic approach that begins at the outset of development. At this time of unprecedented urban growth, a unique opportunity exists to plan smart, sustainable communities.

The most inherently sustainable structure, the supertall tower, is also the cornerstone of the modern city. More than any other structure, skyscrapers serve as landmarks for cities and nations. Like the city, the supertall form is enjoying a revival. Following a nearly 30-year period during which the Sears Tower held the record for being the world's tallest, by 2009 three different buildings will have held the title in five years. High visibility, combined with efficiency and the ability to house dense populations, is making supertall increasingly popular amongst growing cities.

Though height is the chief reason for the skyscraper's popularity, it is also a large contributor to the structure's sustainability. Just as cities are inherently sustainable communities, skyscrapers are inherently sustainable buildings, due largely to efficiency and minimal land impact. But just as more environmentally conscious urban design can produce greener cities, skyscraper design can progress beyond 'efficiency through density.'

Developments that have a greater understanding of environmental context will support healthier lifestyles and respond to the changing needs of the planet. Buildings designed in response to their environments will make the best latent value of their site and generate natural, environmentally-friendly energy. This approach, which takes into consideration building orientation, daylighting, generation of wind power, solar absorption, and a site's geothermal properties, represents a fundamental change in the design process, in which form facilitates increased performance. The methodology, termed 'global environmental contextualism' by the office of Adrian Smith + Gordon Gill Architecture, is predicated on the understanding that everything within the built and natural environment is connected, and that a building's design should stem from an understanding of its role within that context---locally, regionally and globally.

Such a pluralistic approach acknowledges the interaction among building systems as well as between those systems and the natural environment, and seeks to improve each individual system's performance. By using this principle in the design of buildings, architects can create structures that relate symbiotically to their environment, not only reducing their negative environmental impact, but in some cases, virtually eliminating it altogether.

'Global Environmental Contextualism', while a universal concept, is especially applicable to supertall structures. Due to their height, high rise structures act as 'sails' in the wind, disrupting natural patterns and creating harsh local weather conditions. To limit this effect, the buildings often 'telescope', reducing their floor plate size as they grow. This sheds wind vortices, reduces loads and improves structural performance. But this approach fails to take advantage of the power of the natural environment. In contrast, supertall buildings formed to work harmoniously with their environmental context can harness natural energy while simultaneously resolving structural and performance issues.

The 111-story Samsung Togok Tower, designed in 1995 but never built, was envisioned to be a 'working laboratory' for sustainability. Designed by Adrian Smith at Skidmore, Owings & Merrill, the building's tapered form incorporated several large sky atrium openings, designed to re-direct oscillating wind forces. Wind driven turbo generators in the atrium then captured air movements, generating power for the building.

Ten years later, the concept of forming a building to take advantage of natural forces was further refined in the design of the supertall 'Zero Energy' Pearl River Tower in Guangzhou, China. Designed by Gordon Gill with Adrian Smith at SOM, the project is designed to work in complete symbiosis with the environment, harnessing natural power to produce as much as much energy as it consumes. The tower is oriented and formed to take advantage of local wind patterns. The curved façade funnels wind down the vertical face of the tower, accelerating the air toward a series of turbines. The building takes advantage of solar patterns, incorporating a light scoop on the ground floor to maximize natural light and absorbing the sun's energy through photovoltaic elements etched within the tower's glass surfaces. This utilization of latent, natural energy sources combines with over 30 other efficient building systems to provide enough natural energy to fully power the building, reducing its effect on the natural environment to essentially zero.

While new developments like Pearl River Tower can help lower the carbon footprint of a solitary piece of land, existing low-performance, inefficient buildings will continue to pollute the environment. The development community needs to address existing structures. Incorporating green technologies into these buildings will help curb emissions, but the reality is that some inefficient buildings will be slow to evolve. The next generation of sustainable development must compensate for these large carbon emitters, by naturally generating excess energy.

'Positive Energy' buildings are already under development. In Chicago, Adrian Smith + Gordon Gill Architecture's 321 South Wacker office tower continues the progression of the highly sustainable, supertall tower. Building on principles of aerodynamism, biomimcry and global environmental contextualism, 321 South Wacker incorporates new technologies, advanced building systems and even greater flexibility to harness natural forces. Recognizing the unique wind conditions already in place in dense urban areas and the fact that it is not always feasible to allow for openings in through buildings, 321 South Wacker captures wind as it accelerates around building corners. As wind speed increases at higher floors, the placement of wind turbines becomes increasingly dense as the building grows. At the apex, a domed double roof cavity pulls in air, capturing wind at its fastest speed and generating a maximum amount of power. The excess power generated through faster wind speeds, advanced photovoltaics and a host of other sustainable initiatives contribute to 321 South Wacker's extreme sustainability.

Positive Energy buildings like 321 could one day store or trade energy with neighboring buildings, supporting themselves as well as the local community, through efficient distribution of energy to buildings in close proximity. This concept could grow into a network of energy-generating and sustainable buildings, resulting in net zero-energy city blocks, neighborhoods---even cities---and serve to promote a new standard for sustainable, responsible lifestyles. In the context of global development, and in a time when entire cities are being designed and built from scratch, these environmental goals are not only attainable, but vital to our survival.

Urban migration rates are estimated to remain high for the next 50 years. The United Nations projects that the world's population will be 9.3 billion by 2050, and that of the ten most populous nations in that year, only the United States is currently industrialized. The U.S. must begin today to set new standards for sustainable design in the global community. Programs to drive new standards are already underway, such as the 2030 °Challenge, which calls for the building community to greatly reduce fossil fuel consumption in all new buildings, and completely eliminate carbon emissions in all new buildings by 2030. At the local level, U.S. cities including New York, Boston and Seattle have developed strong policies to encourage green building construction. The federal US government must follow this example and mandate sustainable building in our cities and across the United States, setting an example for development and the creation of the sustainable community of the 21st century.

It is the responsibility of the design community to help make the "sustainable city" real. Planners and architects must export their knowledge worldwide to help countries experiencing the greatest environmental stress. In the end, it is the age-old concept of respect for the land and one another that will guide the development of the sustainable city: a truly global concept that strikes chords across the world.

Gordon Gill, a partner at Adrian Smith + Gordon Gill Architecture in Chicago, Illinois, is involved in performance-based designs that work symbiotically with their natural surroundings, contribute to the sustainability of cities, and create an optimal user experience. (Carrie Neill contributed to the article.)