This
large office and retail complex of 1.2 million square feet total was to be located
adjacent to a busy freeway and a major sports complex. Phase I (design completed
Fall 2001) includes 800,000 square feet in three atrium office blocks with low
rise retail to the south. The objective of the client and the architects was to
create a nearly transparent building, highly visible from the freeway and unique
in the Bay Area. The client also specified that the building must receive LEED
certification to fulfill terms of the financing. We worked with the architect
and design team from early in the schematic design phase on issues of daylighting,
glazing, curtain wall issues and sustainability certification, including initial
studies for wind turbine generation. The large and deep floor plates in
Phase I vary from 250 feet by 180 feet at the base of the scheme to the much smaller
plates of 155 feet by 120 feet in the towers. Such large plates are a real challenge
to daylight, but the scheme is based on the insertion of substantial atria into
each of the three office blocks. These atria are designed to be as transparent
as possible, delivering daylight and acting as an exhaust plenum for the mechanical
system while providing an enhanced social space for each cluster of offices. The
exterior glass facing south is clear, single pane with deep horizontal catwalk
grates designed with the structural system to intercept and diffuse direct sun
during the summer months. Radiance simulations were used to study the potential
character of various atria west wall conditions. In concert with the atria
as a plan strategy, the section of the offices is developed with a 13' 4" floor
to floor height. Collaboration with the mechanical and structural engineers enabled
the underfloor system and structure together to take only 2'-0" of this dimension,
leaving an 11'-4" floor to ceiling height for admitting daylight deep into the
office floors. Part of the sustainable strategy developed for this building involves
the issue of seismic response and structural design. Seismic codes in California
are written to protect human life but not necessarily to protect the building.
Post-earthquake occupancy is not a consideration in the seismic requirements,
with the result that occupant safety in a major quake may be enured but building
damage may also be enough that many buildings cannot be re-occupied without major
repair or rebuilding. The client requested from the design team to include
building re-occupancy and continued as part of the design. This required the structural
design to address a much higher standard of building response than that required
for human life and safety. The structural post-occupancy strategy was to be submitted
under the Innovation in Design credits during LEED certification. The design required
a deep spandrel beam to run just behind the curtain wall glazing, initially blocking
over 5 feet of the upper glass and reducing the effective window head height to
7'-3". With review and discussion, this beam was redesigned as an open truss providing
a high degree of transparency. A deep interior light shelf, working with the extended
horizontal mullion cap at 7'-3" up from the floor, intercepts and reflects direct
sun entering the upper glazing panels. A further rethinking of standard
practice addressed the issue of shades necessary to diffuse direct sun in the
offices on clear days. The mechanical roller shades mounted separately for the
clerestories and the view glass are classified as required tenant improvements.
They are automatically controlled by the the building automation system with protocols
developed by us to maximize the use of daylight while reducing the admittance
of direct sun on to the workspace. Lighting controls are included to effect the
energy savings possible through the coordinated design. In addition, the glass
specified is a clear glass with high performance coatings designed to admit the
least amount of heat for the greatest amount of light. This design enabled a large
relatively uprotected south clear glass facede to be both energy efficient and
at the same time ensure a glare free daylighted workspace. This design
is also unique in the determination of the client to explore the less obvious
credits available in the LEED rating system. The site is among the windiest in
the Bay Area and large-scale wind turbines were studied for this site as part
of the overall project. The turbines, coupled with PV arrays on the available
roof areas, address the three Renewable Energy points available under Energy and
Atmosphere. Electricity generated on site could be used by the offices and excess
sold as renewable energy to the neighboring residential developments. The projected
energy generated would have exceeded that required by the development, in this
way contributing to the reliability of the grid, particularly during periods of
high demand. | 
