clarke urban regeneration

1056 Chapel Street, New Haven, CT 06510 | T: 203.777.2515 | F: 203.787.2856 © Pelli Clarke Pelli Architects 2012

Pelli Clarke Pelli Architects 1

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

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

By Fred W. Clarke, City Connect (2012)

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 (2007-2017), a public rooftop park will become the center of a new neighborhood and an emblem of a sustainable future.



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)

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.

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.



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.

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;

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.



• 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.

Cajasol

Seville, Spain (2003-present)

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

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.



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.

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.

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.



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)

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

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.



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 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



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.

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.

Conclusions

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.

clarke urban regeneration

Documents

themes of urban regeneration

environmental sustainability

longterm economic development

large urban projects

pelli clarke pelli architects

pelli clarke pelli projects

development professionals

issues of sustainability