The Architect’s Role in Urban Regeneration, Economic Development, and Sustainability

Achieving urban regeneration, environmental sustainability, and economic development requires the commitment of the designer, the client, political leaders, and society at large. At the Transbay Transit Center in San Francisco (20072013), a public rooftop park will become the center of a new neighborhood and an emblem of a sustainable future.

As our quickly globalizing, interdependent world moves further into the 21st Century, the themes of urban regeneration, environmental sustainability, and economic development are becoming more and more relevant every day. Our world faces environmental and social challenges at a scale that requires the attention of everyone — from individuals to nations to international organizations. As building and development professionals, we bear a particular responsibility — and have a unique opportunity — to lead the world in the search for long-​term, practical solutions that take advantage of our existing urban assets in a sustainable, smart way.

In the following, three Pelli Clarke Pelli projects will be presented — case studies that illustrate some of the unique challenges and opportunities for architecture and development in today’s changing world. Each project engages with the themes of urban regeneration, environmental sustainability, and economic development in varying ways and to varying degrees. As a group, they illustrate the growing centrality of sustainability to large urban projects, many of which are being commissioned by developers, institutions, and governments, often in a collaborative partnership. The projects illustrate how pursuing a program of urban regeneration — a sustainable building practice in itself — can lead to reliable, long-​term economic development.

Sustainability has become an immense subject, and there are many pitfalls to any meaningful discussion about it. One danger is to define it too broadly, making it difficult to draw useful conclusions — instead, one is left with empty generalizations. On the other hand, there is a danger of focusing too closely on the particulars of one project or one strategy, examining technical details that are not applicable to all circumstances. For the purpose of this essay, two themes will be emphasized:

  • how issues of sustainability, urban regeneration, and economic development are particularly exemplified in large urban projects, and
  • how sustainability must be defined not only in engineering terms, but also in social terms: it is a project for all of society to address.

From an architect’s perspective, it must be said at the outset that issues as complex and far-​reaching as urban regeneration, environmental sustainability, and economic development are impacted first by choices made long before a project reaches an architect’s office. These are basic choices, like where a developer chooses to build. They are the choices a city government makes when it implements policies that encourage particular types of development. Most importantly, however, they are the choices a society makes about the ways it wants grow, and the legacy it wants to leave to future generations. In this context, it must be admitted that the individual architect has limited power — the architect doesn’t typically choose the site, nor does he or she make the laws. To produce a sustainable project, an architect must be a part of a larger team committed to sustainable goals. It’s been said many times: great architecture requires great clients. In fact, sustainable development requires much more than that. It requires the attention and energy of all of us — architects, developers, politicians, tenants, and the public at large — because to be effective, it must happen on a national and global scale.

All of this points to the fact that sustainability is not just a technical problem. To be successful, a sustainable project must address its social and economic contexts — in other words, a project must be socially sustainable and economically sustainable. A sustainable project must resonate with its society, providing an environment that attracts and inspires. And a sustainable project must make economic sense — it doesn’t matter how green a building is if it fails in the marketplace.

These issues are especially relevant to Japan, and this book and the conference that generated it are especially timely. Like no other market, Japan’s design and construction industry revolves around the presence of large develop/​design/​build firms. This sort of centralization provides a tremendous capacity for change, through efficient production and economies of scale. Furthermore, historically Japan has shown more concern for energy usage and conservation of resources than many western countries. These factors position Japan to become a world leader in the construction of a sustainable built environment.

In the end, sustainable architecture and urbanism require leadership, political commitment, design, money, open minds, and patience. By nurturing a public discussion about how best to grow and how to do so in ways that ensure a long and prosperous future, organizations like AIA Japan play an essential role in building a sustainable world.

Abandoibarra Master Plan & Iberdrola Tower

Bilbao, Spain (1993-​present)

Conceptual rendering of the Abandoibarra Master Plan in Bilbao, Spain. Iberdrola Tower (shown at an early stage of development) marks the point where the Duesto Bridge crosses the Nervión River.

The Abandoibarra Master Plan and Iberdrola Tower projects, in Bilbao, Spain, illustrate many of the opportunities and challenges for socially responsible, sustainable urban design at a large scale. In particular, these projects illustrate how

  • the public’s view of sustainability has changed over time;
  • large scale projects have particularly large impacts;
  • taking advantage of existing assets is one of the best green building strategies; and
  • addressing the public realm is essential to the social and economic sustainability of a development.

As with most large urban projects, the Master Plan and Tower projects developed over the course of several years, during which time the social and environmental priorities of the client and the society changed significantly. What started as an effort to spur economic growth in a city adapting to the loss of its industrial economy grew to become a project focused on environmental and social sustainability. Both projects are lessons in the inevitability of change and examples of the ways in which a client and a design team must remain flexible over the course of a long project.

Abandoibarra Master Plan

Pelli Clarke Pelli won the competition for the Abandoibarra Master Plan in 1993, four years before Frank Gehry’s Guggenheim Museum would bring a cascade of international fanfare to this provincial city. Located just inland from the Bay of Biscay on Spain’s northern coast, Bilbao is a gritty, industrial city, occupying the green hills that surround the curving River Nervión. In its heyday, Bilbao was a port and an industrial town, and from the middle of 19th Century it used its riverfront for shipping and manufacturing. By the middle of the 20th Century, however, like many cities, Bilbao’s economy was shifting away from heavy manufacturing, and as a result it was left with dirty void at its center.

Realizing the potential of the site to help reinvent Bilbao for the 21st Century, a public entity was created to attract investment to the waterfront and to use the money raised from leasing building sites to fund the creation of public parks and other amenities. The Guggenheim Museum was one element of this redevelopment effort.

Pelli Clarke Pelli was commissioned to plan an area of the riverfront stretching from the Guggenheim west to Doña Casilda Park, a turn-​of-​the-​century urban park with picturesque paths winding through a rolling landscape of ponds and large trees, and bordered by some of Bilbao’s fine 19th Century buildings. The site for development was a one-​kilometer-​long rail yard, which formed an impassable barrier between the city and the river.

The design team proposed to start from scratch: remove the rail yard and reclaim the waterfront for the residents of Bilbao. There was a challenge, however. At the boundary of the rail yard and the existing city was a sudden, 16-​meter drop in elevation — a deep cut running the length of the site. This change in elevation would lead to one of the major elements of the master plan: the construction of a gradual slope starting at the existing city and descending to the river’s edge, making it possible for pedestrians to reach the waterfront without having to negotiate stairs or ramps, and providing a seamless and welcoming transition from city to river. This also provided the opportunity to hide five thousand parking spaces below grade, freeing the site of traffic and providing additional parking for the new buildings on the site.

Across this gradually sloping platform — effectively a mile-​long tabula rasa in the center of a large city — four existing urban elements were extended and emphasized: the natural setting of the River to the north; the Doña Casilda Park to the west; the Guggenheim Museum to the east; and the Beaux-​Arts avenues of the existing city fabric, running from the south to the river and across an existing bridge.

To weave the newly developed area into the street life of the surrounding city, two avenues were extended through the site. The first, Calle Elcano, runs from one of Bilbao’s prominent traffic circles, through the site, and across a bridge, the Puente de Duesto, to the north side of the River. A new public plaza was introduced onto the avenue, using formal language that resonates with the existing city and providing a focal point for the new Master Plan. The Master Plan called for a tower adjacent to the plaza that would be visible from all parts of Bilbao — an obelisk, or beacon, marking the center of the new development.

Another street, Calle de Juan de Ajuriaguerra, was extended through the site, running east-​west and intersecting with the Calle Elcano at the new public plaza. This street defines the south edge of the Master Plan, along the boundary with Doña Casilda Park, and is the site of several new, lower buildings, matching the heights of those in the existing city. As the properties have been leased and the new buildings’ programs have been defined (with the input of Pelli Clarke Pelli), a rich mix of uses and design styles has taken root. There is a hotel by Ricardo Legorreta; a shopping center by Robert A.M. Stern; and apartment buildings by a number of distinguished Spanish architects; and soon there will be a university building by Alvaro Siza and a library by Rafael Moneo. Over time, there will be upwards of two million feet of new construction and a very broad mixture of public and private endeavors. The variety of programs is essential to the Master Plan’s success, attracting diverse groups of people to the area, and animating the site at all times of day — in other words, making a truly urban space.

Often smart urban planning is, by its nature, sustainable. The Abandoibarra Master Plan calls for two-​thirds of the site to be occupied by public green space. A generous promenade, now built, lines the river’s edge, and has quickly become one of Bilbao’s most popular gathering spaces. Approached by foot from the city, visitors traverse a formal urban park, with grassy fields and curving rows of trees, to a strand of broad stone staircases that descend the last few feet to the river walk, providing casual seating for people watching and gathering. A line of tall, angular lamps marks the curve of the river and gives the plan vertical expression. These elements were conceived in the mid-​1990s mostly for reasons of restoring the public realm and generating economic growth. By the early 2000s, however, as sustainability was growing in importance for municipalities, the original Master Plan and landscape design resonated very comfortably with the city’s new interest in green design.

The site, which drops 16-​meters between the city and the river, is covered by a concrete platform topped by a public park. Streets and parking are underneath, allowing city dwellers to walk to the river’s edge unimpeded. A riverfront promenade connects the Guggenheim Bilbao to the new development.

Iberdrola Tower

By the time Pelli Clarke Pelli was awarded the commission to design the Tower for Abandoibarra — the centerpiece of the Master Plan — in 2005, environmental sustainability had become an urgent public priority, especially in Spain. Nonetheless, as a private development project, it was not a foregone conclusion that the design would embrace the tenets and technologies of green design.

Early in the design process, the tower was leased to Iberdrola, Spain’s largest power company and a global leader in the production of alternative energies, and their arrival signified an opportunity to emphasize the green elements of the design. To the design team’s surprise, however, Iberdrola was not so enthusiastic at first. They were even resistant to applying for LEED certification, which they feared was an administrative burden that would increase their costs without resulting in a meaningful financial benefit.

LEED — or Leadership in Energy and Environmental Design — is a green building certification system developed by the United States Green Building Council, a non-​profit organization of building industry professionals. LEED is a checklist of green building strategies that can be applied to new construction or existing buildings in an effort to make them as environmentally responsible as possible — distinguished projects are given a Silver, Gold, or Platinum designation. In many communities, a LEED certified project can receive tax incentives, encouraging developers to build green. In recent years, LEED has gained such wide acceptance that it is even used to promote new projects to the general public, making it an attractive feature to potential tenants.

After proceeding with the design and documentation of the building for several months, in 2007 Iberdrola had a change of heart, and directed the design team — and its sustainability consultant, Buro Happold — to review the design and look for opportunities to make the tower as green as possible. What changed? In short, the market. The value of a certified green project has gone up — in a very short time. The increased costs of building green have become justifiable in terms of the perceived benefits: benefits to a company’s image, savings in energy consumption over the life of the project, and competitive advantage in the marketplace, where potential tenants are making sustainability a part of their leasing decisions. 

Iberdrola Tower has been pre-​certified for a LEED rating of Platinum, the first such building in Europe. Achieving this was the result of the accumulation of several efforts to optimize the design and construction rather than one sweeping design move. These strategies include:

  • highly efficient, state-​of-​the-​art mechanical systems;
  • a high-​performance double wall glass façade;
  • recycled concrete resulting from the demolition of the existing train yard;
  • recycled fly ash — the residue of coal burnt by power plants — in the building’s concrete;
  • materials procured from within a 500-​mile radius of Bilbao;
  • double the amount of fresh air intake required by code;
  • a continuous loop of 30°C water running through the building; because the tower has two occupancy types — offices and a hotel — that are active at different times of day, the water can be used to assist in heating or cooling, depending on the context, and in turn, it can be passively heated or cooled by the two occupancies, again, opportunistically depending on the context; and
  • a plumbing system that collects and recycles grey water.

The double wall glass façade reverses the typical configuration — the permeable wall is on the inside, and the watertight wall is on the outside. As sun heats the cavity between the two, cool interior air circulates through, drawing heat up and into the ceiling plenum. This allows the building to capture the heat and take advantage of it as circumstances determine — for heating in the cooler months, for instance.


Seville, Spain (2003-​present)

Cajasol consists of a tower and two low buildings that form an outdoor shopping promenade. The project, which occupies part of Seville’s World Exposition site, draws from the historic city’s characteristic urban forms: narrow streets that provide shade and towers that are visible from a distance.

Cajasol is a mixed-​use development in Seville, Spain consisting of a tower, two low buildings and a landscaped mall and plaza. The project engages with a web of issues that surround the themes of sustainability, economic development, and urban regeneration:

  • it is a private development built on public land – the largely vacant grounds of a World Exposition;
  • it aims to spur growth in the context of a crowded, historic city;
  • it takes advantage of the local climate and traditional building strategies;
  • it leverages a strong local commitment to sustainability to enlist the support of the development team;
  • it recognizes that scale is directly proportional to impact, and that as a large development, it has an equally large responsibility to its social and environmental contexts; and
  • it engages the public realm to ensure its social and economic sustainability.

Cajasol Planning and Site Design

The medieval city of Seville, the capital of the province of Andalusia, shares important qualities with a number of Japanese cities. The center of Seville is densely packed and very historic. There is little room for development in the downtown area, and even if there were, it would be a great challenge to provide the sorts of services demanded by a modern building, let alone the access needed for large-​scale construction. 

As hard as it would be to build out in this dense urban fabric, however, it is also impossible to build up. By law, building heights are limited in an effort to preserve the prominence of Seville’s historic towers on the skyline, especially the Giralda, the bell tower of the Seville Cathedral, which was originally a minaret of a Moorish Mosque.

These constraints have made it difficult for Seville to grow, and the city has tried a number of strategies to encourage development without disturbing the historic city center. One such strategy — familiar to Japanese architects and planners — was to host a world exposition, which Seville did in 1992, in the hopes that the exposition facilities would sow the seeds for future growth. Unfortunately for Seville — and many other cities — this strategy has not often been successful. Exposition grounds around the world — or Olympic sites, for that matter — tend to founder after the events have passed, often leaving large voids on the outskirts of cities, failing to deliver on their promises of economic development. This was the case for Seville. Luckily, instead of being located far from town, the Seville fairground is adjacent to the Old City, just across the Gaudalquivir River. It provided an opportune area for new development that could become part of the center city rather than — in the parlance of the urban planner — an Edge City or Exurb.

Seville has one of the world’s most forward-​looking energy codes, as well as an aggressive program to develop alternative energy sources, like wind and solar. For instance, the city is currently building a series of “concentrating solar power plants”— arrays of mirrors that focus sunlight on a large tank filled with salt that heats up, becomes liquid, and produces steam to turn a turbine, thereby making electricity. Remarkably, in five years, by 2013, these plants are anticipated to provide all of Seville’s electricity, without creating any greenhouse gases. The political context that supported the investment in these and other advanced green technologies made it possible — in fact, almost compulsory — for Pelli Clarke Pelli to design a highly sustainable project, even in the context of a commercial development.

The site is at the south edge of the Expo fairground, with quick access to one of Seville’s main approaches, the Puente de Chapina. The site is a 300-​meter by 120-​meter rectangle, flat, and bounded by existing streets, with little around it. Presented with a blank slate, and with little in the immediate vicinity to respond to for inspiration, the design team decided give the block a self-​sufficient character — to create density and energy on the site by placing the public attractions — dining, retail and an auditorium — on the interior of the block. Not wanting to hide the public space, however, the block is open at each end, and the two buildings that enclose the sides are low and slope down to grade, minimizing their bulk and presenting a welcoming posture to visitors.

The negative space between the two serpentine buildings at Cajasol forms a curving street at the base of the tower. The buildings slope down to grade at each end, allowing pedestrians to easily access lushly planted rooftop parks.

Although the areas directly adjacent to the site did not provide an inspiring context for the design team to respond to, the Old City, just across the River, possesses several meaningful and unique urban forms. For instance, the narrow, twisting streets of the medieval city are perfectly suited to provide cool shade in Seville’s hot, bright climate, and they bustle with activity. In addition, groves of fruit trees are commonly used to give shade to the city’s medieval plazas, making for intimate, enclosed spaces rather than the large public squares one finds in other European cities. In fact, in many respects Seville’s urban form is closer to the ancient cities of the Middle East, which stands to reason, since southern Spain was under Moorish control for over 500 years.

To resonate with Seville’s unique urbanism, the design team decided to create a “street” on the interior of the site, rather than a plaza. Two long, low buildings were placed along the edges of the site and pinched together, bending the plan of each toward the interior of the block. The residual figure has an hourglass shape, wide at the ends and narrow in the middle: the result is the “street”, shady and filled with people. Each building is covered by an occupiable green roof. The buildings’ roofs slope down to grade at each end, allowing pedestrians to follow paths directly from the sidewalk onto, up, and over the roofs, which are generously planted with diverse varieties of local flora. The ground floors of the two buildings are lined with welcoming storefronts and cafes, and offices fill the three stories above. It is traditional in Seville to stretch sheets of canvas from rooftop to rooftop, shading the narrow street below, and adding to the sense of enclosure. The design team took advantage of this wonderful tradition by stretching a system of tensioned cables over the new street and draping fabric shades over them in a loose, striped pattern. The shades are adjustable and respond to the position of the sun. Finally, at the north end of the shopping street, a shady grove of fruit trees fills the space, much like the plazas of the old city. Below the trees, underground, is an auditorium.

Despite the creativity of the design solutions, it is important to emphasize that this project is eminently rational. In order to have a chance of winning the competition — and for the project to be successful in the long term — the proposal needed to make economic sense. It had to be profitable, and therefore, it needed to be buildable and leasable. Seville’s ambitious green building program created a context in which we could be adventurous with our proposals, but ultimately they had to survive a cost-​benefit analysis. That they do is particularly well illustrated in the tower design.

Cajasol Tower

The Cajasol Tower is a 37-​story office tower with an elliptical plan that gently tapers as it rises. Its skin is lightly reflective glass with horizontal bands of exterior shading devices that striate the facades, expressing the ellipse and adding visual complexity. The structure and service core sit within the building envelope, giving the building an idealized form, uninterrupted by large structural members. 

The tower’s top story is a public observation deck, capped with a sloping roof that at its highest point is 22-​meters above the floor, creating a large airy space to view the historic city center of Seville. From within the Observation Deck’s space, a crown of expressive structural members extends upward from the building’s core to support the roof. The Observation Deck is a symbol of the project’s commitment to the public realm: at the top of Seville’s tallest tower, a grand public room, visible from miles around.

The elliptical plan arose from a recognition that some residents of Seville might be uncomfortable with the introduction of a tall building so close to their protected historic city. Towers hold a particular importance to Seville — for centuries, the Giralda has been the tallest structure, soaring over the city, symbolizing its Muslim and Christian history. In deference to this, the long axis of the Cajasol Tower is in line with the Giralda, so when viewed from it, the thinnest profile is seen. The elliptical form also allows the tower to have an attractive profile from everywhere in the city — towers with pronounced corners have “thick” and “thin” silhouettes, depending on where they’re viewed from. The ellipse mitigates this phenomenon, presenting all residents of Seville with an attractively shaped tower.

In a contemporary response to Seville’s tradition of shaded architecture, the Cajasol Tower has an ambitious sunshading design, with a carefully integrated system of horizontal and vertical fins and hanging shades. Each element is sized to respond to the position of the sun as it journeys through the sky. In this, the building becomes a “heliotrope”: its architectural form is generated by the particular path the sun takes through the Sevillian sky. The continuous horizontal sunshades that extend from the edge of the tower’s floor plates grow deeper as they reach the building’s southern face, where the midday sun is brightest. On the east and west faces, the vertical fins are emphasized, blocking the low early and late day sun. The strips of horizontal blinds are shorter or taller depending on their position. The sensitive viewer can read the sun’s impact on the building by looking closely at the configuration and depth of the shading devices. In one final, heliotropic move, the Tower’s top is angled toward the south, and it is covered with an array of photovoltaic cells. Not only does the Tower’s form reduce the impact of the sun, passively reducing heat gain by shading; where it can, it opportunistically soaks up the sun’s radiation, turning it into an asset.

Transbay Transit Center and Tower

San Francisco, California, USA (2007-​present)

The Transbay Transit Center in San Francisco is five blocks long and topped by a public park. Transbay Tower is adjacent and was designed in concert with the Transit Center. The project is a unique public-​private joint venture: the Transit Center is funded in part by revenue from the sale of the land for the Tower.

Partnering with the real estate developer Hines, Pelli Clarke Pelli was named winner of an international competition to design a new multi-​modal transit center and office tower for downtown San Francisco in September 2007. The Tower will be San Francisco’s tallest by nearly two times, remaking the city’s skyline. The Transit Center, at its base, will become a new typology: a clean and sustainable transportation hub. A 5.4-acre public park will form the roof of the Transit Center and will become the centerpiece of a new and growing neighborhood.

The new Tower and Transit Center are intended to spur economic development by reinvesting in a centrally located part of San Francisco that has missed out on the region’s recent economic boom. The project was conceived by the city as a public-​private partnership, a fact that will help to ensure its economic viability, and thus, its sustainability. The Transit Center, which is replacing an existing and outmoded bus station on the same site, is a public project. To raise money for this ambitious project — the Transit Center is expected to cost several hundred million dollars — architects and developers were invited to submit proposals as teams. The expectation was that a developer would make an offer to purchase part of the site for the construction of a tower, and the purchase price would be used to fund the construction of the public Transit Center. Teams could propose whatever mix of programs they felt appropriate for the tower.

If successful, Transbay will become a new standard bearer for large-​scale urban sustainable design. Implicit in our design are several assertions about what makes a city sustainable:

  • Placemaking” can be an engine for growth.
  • A new public park can be the generator of a new neighborhood.
  • Public-​private partnerships are beneficial to the success of large-​scale public developments.
  • A Transit Center, typically a polluting building type, can be an environmental symbol.
  • Large scale equals large impact.
  • The general public must be given a voice in the design process.

Transbay Transit Center

The existing Transbay Terminal is located on the east end of Mission Street in Rincon Hill, on the edge of San Francisco’s financial and commercial district. Built in the 1930s, the Terminal is San Francisco’s main bus station, especially for commuters arriving from Oakland and Berkeley. Large elevated ramps lead directly to and from the Bay Bridge, forming imposing structures in the neighborhood. Rincon Hill is rundown — a commercial borderland between the bustling city center and the industrial buildings of San Francisco’s once-​busy waterfront. The neighborhood has become a gathering place for the homeless and the location of transient businesses like cell phone stores and fast food restaurants. Nonetheless, Rincon Hill is centrally located and is within walking distance of the many of San Francisco’s great attractions and businesses. It was only a matter of time before city leaders and real estate developers recognized it as a great financial opportunity and urban asset, and in the last couple of years it has become the focus of energetic residential and commercial development.

In the decades since the original Transbay Terminal was built, the Bay Area has developed into a sprawling region, and commuters now travel to the city from long distances. San Francisco’s incredible growth has happened in spite of a meager public transportation system, and it has become clear that to continue growing — and to do so in a sustainable way — the city needs to make a significant investment in public transportation. Currently there is not a conveniently located multi-​modal hub to bring trains, busses, and cars together in an intelligent way. And surprisingly, San Francisco does not have a great point of entry — a Grand Central or Victoria Station to celebrate its status as a global city.

The new Transit Center will be five blocks long, stretching over two existing streets and a pedestrian alley. The architecture employs an exoskeleton — a line of steel “baskets” or “petals” that form the exterior walls of the building. The open structure allows for a light-​filled, airy space that expresses a new vision for transit center design: clean, light, and open. On the exterior, the rhythmic pattern of glass and steel will sparkle in the sunlight and emit a warm, welcoming glow in the evening. At grade, shops and restaurants will enliven the street, attracting commuters and neighborhood residents alike.

The heart of Pelli Clarke Pelli’s proposal is City Park, a large public park atop the new Transit Center.  Parks have played a central role in the development of the modern city, providing growing communities with a cultural focal point and a space of repose. Early San Franciscans in particular recognized this, setting aside land for parks before neighborhoods even existed. With little open space available in the blocks around Transbay, the rooftop of the new Transit Center presented a great opportunity to provide a park for the surrounding neighborhood, and at the same time, reduce the negative environmental impacts of the bus terminal.

In City Park, visitors can discover several distinct Northern California ecologies, as well as a variety of artworks, activities and public spaces. Waterways will define the long edges of the park, supporting a range of natural and exotic flora and fauna. On the north side, a flowing stream runs from west to east, cleaning and storing storm water and pretreated greywater from the Transit Center and the Tower. Along the south edge of the park, there is a shallow, meandering wetland, planted with water flora. Between the two is a gently undulating landscape that is home to a series of distinct ecologies native to the San Franciscan landscape: grassland, riparian, chaparral, marsh, and oaks. An extensive interpretive program will make City Park an educational space, explaining the natural processes on display.  Social spaces are woven into the natural landscape, including playgrounds, a children’s garden, gathering spaces, a half-​mile jogging path, cafés, and an amphitheater. City Park will host concerts, street theater, political meetings, interpretive lectures, art and craft shows, and neighborhood gatherings.

A multi-​modal transit center, by its nature, has a profound impact on its surroundings. It is a concentrated source of exhaust from cars, buses, and trains, and due to its 24-​hour-​a-​day activity, it uses resources and generates pollution at a rate much greater than other buildings. At a minimum, there is an ethical obligation to reduce the effects of the Transit Center on the neighborhood. The design team concluded, however, that it is possible to go much further — that in fact it is possible to design a transit center that benefits the environment.

In the design proposal, exhaust from the buses and the central power plant are captured and filtered through biological systems in the Park that absorb and process carbon dioxide. To reduce the energy required to cool the building, the size of the Transit Center’s footprint makes it possible to take advantage of “ground coupling” — a process that harnesses the relatively low temperature of the Earth to chill water passively. Pipes will be coiled around the foundation’s concrete pilings, circulating water deep below grade. The waterways of City Park are used to recover and treat the Tower’s and Transit Center’s greywater, allowing the water to be reused for landscape irrigation, cooling towers, and restrooms. The large scale of City Park is another benefit. What would otherwise be a five-​acre roof, absorbing and radiating heat, will instead be a green, cool park, reducing the effect of San Francisco as an “urban heat island.”

Transbay Transit Center uses several strategies to reduce energy consumption and mitigate its impact on the surrounding city. The public rooftop park, initially an idea about urbanism, is the centerpiece if the Transit Center’s sustainability program, helping to filter bus exhaust and reducing the “urban heat island” effect.

Transbay Tower

Transbay Tower will be the tallest building in San Francisco, joining the Golden Gate Bridge and the Transamerica Building as one of the skyline’s defining images. Thus Transbay Tower has a special obligation to be exciting and to respectfully complement its surroundings. We believe that, like San Francisco itself, the Tower should be urbane and dignified, classic and contemporary — a memorable icon. 

To be a good citizen, Transbay Tower will need to balance the natural power of its height and scale with its impact on the skyline and the growing neighborhood at its base. Our thirty years of experience in tower design has taught us that the taller the building, the simpler the form should be. With this in mind, our proposal is in the architectural tradition of obelisks and pylons, but with a contemporary scale and expression. The 1200-​foot-​tall, 80-​story Tower has a slender, tapering silhouette that emphasizes verticality.  The walls are composed of metal and high-​performance, lightly coated glass, resonating with the material expression of the Transit Center. A screen of horizontal metal fins articulates each floor, providing light shelves and solar shades for the interior space, much like the Cajasol Tower in Seville.

Transbay Tower employs several green building strategies. The metal sunshades, working in concert with opaque bands of spandrel glass that rise to sill height on every floor, are carefully calibrated to maximize light and views while reducing solar gain. Paired with high performance, low-​emissivity glass, the building’s cooling load is reduced significantly, potentially resulting in energy savings of 15% relative to the standard baseline. The cooling that is required will be provided in part by heat-​exchanging coils wrapped around the Tower’s deep foundations, harnessing the constant, cool temperature of the earth, once again reducing the Tower’s dependence on public utilities.

In addition to energy reduction, our proposal also addresses indoor air quality. A band of louvers at each story, carefully coordinated with the building’s structure and skin, work with dedicated fans to provide 100% fresh air at every floor. It is expected that these strategies will result in a LEED rating of Gold, a significant achievement for a tower of this size.

Above the 80th floor, the glass in the curtain wall stops, but the metal elements of the Tower continue to rise and taper. This subtle change in the building envelope gives the Tower an expressive top, while maintaining the simplicity and natural verticality of its form. Within the space created by the metalwork is an array of visually expressive wind turbines generating power to light the Tower’s top. The faster the turbines spin, the more electricity they create, and the more intensely the light glows. The breezes from San Francisco Bay are continuously registered and made visible, reinforcing the environmentally sensitive attitude of the Tower and the Transit Center.

It is hoped that Transbay Tower will become a symbol of a new approach to sustainability, one that unites the ambitions of the city, the developer, the environmentalist, and the residents of the neighborhood. All of these important constituencies have a stake in the success of the project. On a broader scale, sustainability requires the support of everyone, everywhere. We need new models that unite all of us in this global effort.


As sustainability has gained prominence in recent years, Pelli Clarke Pelli has reconfigured its practice to support new, sustainable forms of collaboration and design. From our efforts to educate clients about the necessity and benefits of sustainable design to our ongoing mission to expand our palette of green building strategies, we have organized our practice around several important principles.

  • Design economically sustainable projects.

Understand that economic viability is essential to environmental sustainability.

  • Design socially sustainable projects.

To be sustainable, projects must grow from their unique social context.

  • Encourage Densification and Urban Regeneration.

Help your community understand its existing assets and how they can be improved and reused.

  • Recognize that projects don’t stop at the property line.

A building impacts its neighbors and its neighborhood, and must always be, as my partner Cesar Pelli has often said, “a good citizen.”

  • Encourage dialogue about sustainability.

Get involved in the public discussion so developers and institutions make smart decisions about growth.

And finally,

  • Educate yourself, educate others.

Stay on top of new technologies and strategies for sustainable design.

Share your knowledge with people in positions to make a difference.

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