New Shade of Federalism
The General Services Administration's great architectural awakening came 10 years ago, with the implementation of its Design Excellence Program. In recent years, sustainable design has become a primary component of design excellence in GSA projects. Since 2003, the GSA has required all its buildings to receive certification (or, better still, a Silver rating) through the U.S. Green Building Council's LEED green-building rating program.
Sustainable design has become a dominant theme in a trio of high-profile, big-ticket GSA building projects whose very size and dimension reflect the significance of their purpose and symbolize the characteristics of a strong and enduring government.
The Seattle Federal Courthouse, Los Angeles Federal Courthouse, and San Francisco Federal Office Building take a holistic approach to sustainability, treating the concept as an integrated process in which each building's site, its place in the context of the urban environment, its functional program, and its massing figure as much into the overall sustainability of the projects as do the individual green components that comprise the buildings.
Although the new Seattle Federal Courthouse predates the Design Excellence Program, the design of the project, which opened in September, takes a "holistic approach that ties into sustainability," says Steve Connell, AIA, principal for local lead architect NBBJ. "You can build the most energy-efficient building in world, but if you just have one long row of offices, how sustainable is that?"
Building orientation is crucial to all three of these new Federal buildings. With each building being located in a dense urban environment, their site and local climatic conditions were central to their planning and design. NBBJ conducted solar analyses to determine where the most light would be distributed onto the site and how to plan the layout of courtrooms and offices to maximize the use of natural light.
During design of the San Francisco Federal Office Building, now under construction, Los Angeles firm Morphosis studied climatic patterns, focusing on temperature and wind. The result is the design of a narrow 18-story tower with operable windows, a greatly downsized mechanical heating and cooling system, and an innovative metabolic skin (called a "living machine") made of rotating metal panels that envelopes the tower's exterior, providing shade and blocking out heat and glare.
A self-professed nonbeliever in green architecture, Morphosis principal Thom Mayne, AIA, says he's interested in architecture as gestalt, looking "at architecture in response to the urban environment, the workplace, and energy."
Chicago's Perkins + Will planned the orientation of the one-million-sf Los Angeles Federal Courthouse in accordance with the path of the sun, the city grid, and the historic city hall (which sits diagonally across the street). A southeast-facing entry portal provides a visual connection between the courthouse and city hall.
The courthouse's innovative iconic element takes the form of a towering, south-facing, 80,000-sf "metamorphic energy wall" made of glass and photovoltaic panels collecting solar energy to power a small portion of the building's energy needs and providing an energy-saving enclosure for the building's grand atrium.
Nearly finished with its design, Perkins + Will will soon turn the project back over to the GSA, which will let the next phase of the bridging contract out for bid. Construction is expected to begin in 2006, with completion in 2010.
Let's take a look at the sustainability features of these remarkable GSA projects.
Daylighting measures are pushed to the extreme in each of the projects. To make the most of daylighting, NBBJ separated the Seattle courthouse — dubbed by a local newspaper the "courthouse of light" — into three sections: courtroom tower, judges' chambers, and office.
Courtrooms in the tower were arranged two per floor, with one on the east side of the tower and one on the west, to maximize natural light. Inside the courtrooms (which are standardized in size, a first for Federal courthouses, with three judges sharing the two courtrooms per floor to reduce the total number of courtrooms required) light shelves, light scoops, and articulated ceilings fill the rooms with light. Outside of the courtrooms, usually cloistered transactional spaces where cases are filed are opened up and glass doors are installed on attorney-client conference rooms.
Connell says NBBJ's experience in the corporate sector helped ensure that the daylighting measures enhanced the indoor environment in such a way that "the building performs for the people that work in it." Sustainability is "not about just installing triple-glazed glass," he says.
Perkins + Will's strategy for lighting a deep floor plan was key to winning the Design Excellence competition for the Los Angeles Federal Courthouse, says principal Ralph Johnson. Natural light is a fixture in the courthouse's 41 courtrooms, with light entering the courtrooms from the north and south via clerestory windows located above secured corridors. The south-facing secured corridor looks out onto the glass curtain-wall-enclosed atrium, says Perkins + Will principal Aki Knezevic, AIA, LAP. On the north back-of-house side of the building, judges' chambers are arranged in an alternating series of vertical columns and lightwells. The lightwells "break apart the columns, allowing the penetration of light into the building," says Johnson. Perkins + Will expects a 20–40% reduction in electrical loads for lighting.
In the Seattle courthouse's office wing, 70-foot clear spans allow for easy access to daylight. "It's much more like a European office wing, where they have regulated standards for daylight," says Connell.
When completed in early 2006, the San Francisco Federal Office building will be illuminated using natural light through 80% of its space. The amount of energy consumed by lighting is expected to be reduced by 26%, says Morphosis's Thom Mayne.
The goal of providing as much natural ventilation as possible in the building drove Morphosis and the Los Angeles office of engineering firm Arup to perform initial studies of temperature and wind patterns, which led to the design of an extremely narrow 65-foot-wide tower with clear spans. The design produces loft-like workspaces that are heavily daylit. "We eliminated the hierarchical structure of private offices," says Mayne. "There are no corner offices in the building. The emphasis is on natural light, fresh air, and flexible office space for a sustainable workplace."
Natural light lends a special nuance and a "sense of majesty" to both the Los Angeles courthouse's glass atrium and the Seattle courthouse's skylit portico, says NBBJ's Connell. "As you enter the portico [in Seattle], it's flooded with light on all sides."
Engineering out energy usage is also crucial to these three structures. The temperate climate in Seattle, as well as San Francisco, means that heat-gain issues associated with the extensive use of glass and glazing may be less of a concern than in a city such as Los Angeles. However, with the U.S. consuming 25% of the world's energy, Morphosis's Mayne says it's important to reduce energy consumption across the board. "We believe we have a fundamental responsibility to take on these issues," says Morphosis project manager Tim Christ.
Each of the design teams uses a combination of methods to cool and heat the three projects, with underfloor displacement air ventilation and radiant heat being common components of all three projects. In Seattle, a conditioned zone design enables four air-handling-unit zones to serve the 60-foot-high main entry lobby and the courtroom lobbies in the tower. An indirect/direct evaporative cooling system and a displacement air ventilation system will cool by exhausting warmer, lighter air through the top of the atrium, while cool, clean air is delivered at extremely low velocity at floor level to the first six or seven feet of space. The system is "ideally suited for transitory public spaces," says NBBJ's Connell, because they are not required to be kept at an optimal 69 degrees.
Above the fifth floor, Morphosis' Federal office building uses operable windows and horizontal awnings that can be slid out four inches to let in fresh air. This, combined with the metabolic perforated metal skin worn on the building like a jacket, enables 70% of the building to be cooled without the use of mechanical air-conditioning, says Mayne. This equates to an estimated 86% reduction in annual operating costs for cooling. Due to security needs and heavy computer-server requirements, displacement air ventilation is used in the lower levels of the building.
Cooling is also reduced through the process of thermal storage, which enables the building's concrete skeleton to store much of its cooling energy at night and disperse it during the day. On the southeast façade, the metabolic skin is designed to act like a sunscreen to reduce heat gain. A chimney effect is also created between the screen and the tower's glazing, which pulls warm air out of the building and up the stack space.
Solar wall reduces energy use
Culminating in a statuesque spire, the Los Angeles courthouse's curving metamorphic energy wall is comprised of 60,000 sf of clear glass panels and 20,000 sf of monocrystalline photovoltaic panels. Spawned by Perkins + Will's Ralph Johnson and Guy Battle of Battle McCarthy during an encounter in Chicago, the concept of a "solar wall" that is both a solar collector and energy-reducing atrium enclosure is a unique and has required close collaboration between the two firms. The genesis of the wall, says Johnson, was formulated during the course of the six-week Design Excellence competition "and we've been trying to make it work for three years. The design has changed, but the concept has held together."
The limitations of current photovoltaic technology will only enable the wall to provide 2–3% of the building's energy. But Perkins + Will's Aki Knezevic says the wall is designed to be flexible and will be able to be modified as technology advances. The number of panels can be adjusted as needed to supply varying amounts of energy. The payback period for the wall is 10–15 years.
Computational fluid dynamics modeling enabled the energy wall to be designed to work in unison with the building's air displacement ventilation system to reduce the energy required to heat and cool the building. In terms of energy usage, Knezevic says the building's 40,000 BTUs per year is below ASHRAE standards and well below GSA guidelines.
It seems counterintuitive, Knezevic says, but "by using high-performance glass and variable-ratio photovoltaic cells on the wall, you can fine tune and contour the space to bring in more natural light or add more shade as the space demands." Using the technology, it's possible to "engineer a space to produce more energy, provide more shade, and filter heat rays while allowing visible light to pass through it."
According to Knezevic, the design of the wall system and the use of displacement air ventilation cause the atrium to act like a large heat buffer, where the first six feet of air is cooled and warm air is exhausted out through the top of the building. A cavity space in between the glass/PV-panel curtain wall and the perforated stainless steel metal mesh screen that backs it acts as another buffer space through which warm air is upwardly exhausted. The screen filters light entering atrium and serves as a structural component of the wall system, enabling it to meet blast-resistance requirements.
These three buildings are prime examples of how GSA is using its position to advance and showcase innovation in sustainable design in big-budget, high-profile projects. Morphosis' Tim Christ credits GSA's support at the national and local levels for "allowing us to win over some skeptics early on" in the design of the San Francisco Federal Office building. "It would have been difficult to win over people if this had been a spec office" and not a Federal building, he says.