California Academy of Sciences - D+H Mechatronic

® Tim Griffi th / California Academy of Sciences
WORLD OF D+H
Overview of further North American reference objects:
BILL & MELINDA GATES
FOUNDATION
Seattle, USA
Showroom »California Academy of Sciences«
THE BOW
Calgary, Canada
KENDALL SQUARE
Cambridge, USA

2
WELCOME,
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more details from one of our reference objects on the following pages:
The California Academy of Sciences, Renzo Piano´s ecological work of
art building in San Francisco.
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With pleasure we would like to introduce you to the project »California
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of Sciences«.
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ISSUE 01/09
01/09 smart buildings - materials - technologies
Renzo Piano
Building Workshop
Ove Arup & Partners
Barkow Leibinger
Transsolar
VJAA

Golden Gate Park San Francisco with De Young Museum and California Academy of Sciences
East-West Building Section
North side with main entrance Living roof
Photographer: Tom Fox
Photographer: Tom Fox
Photographer: Nic Lehoux
CALIFORNIA ACADEMY OF SCIENCES
SAN FRANCISCO, CA, USA
RENZO PIANO BUILDING WORKSHOP / STANTEC ARCHITECTURE
The California Academy of Sciences in San Francisco is one of the few
Natural Science Institutes where the public experience is directly related
to in house scientific research, done in the same building, since its
foundation. The primary goal of building a new Academy was to provide
a safe, modern facility for Exhibition, Education, Conservation and
Research under one roof. The new building will become one of the
world’s most innovative and prestigious scientific and cultural institutions.
The new Academy is designed on the same site of the previous
facility in Golden Gate Park. This project required the demolition of
most of the 11 existing buildings, built between 1916 and 1976.
Sustainable Design
The mission statement of the Academy, “To Explore, Explain and Protect
the Natural World”, (combined with the mild San Francisco climate)
made this project ideal to incorporate sustainable design strategies.
Not only energy efficient heating and cooling, but also a more holistic
approach was agreed to, involving a serious effort in the choice of
materials, recycling of the materials of the old Academy and the way in
which they are put together. The location of spaces in relation to daylight
and ventilation, the efficient use of water and the run-off from the
roof, as well as the generation of energy are integral to the building
design.
Sustainability is also part of the exhibition design, the exhibition philosophy,
and its day-to-day operation. As a functioning demonstration the
public will be able to see and understand many of the principles of sustainable
design.
The Design
The new building retains the former location and orientation, and like
the original Academy, all functions are organized around central Piazza,
or courtyard. Three historic elements of the previous Academy have
been maintained in some fashion, as a memory and a link to the past:
African Hall, North American (California) Hall and the entrance to the
Steinhart Aquarium.
Two spherical exhibits, the Planetarium Dome and the Rainforest Bios-
phere, are located adjacent to the Piazza. Together with the reconstructed
entrance of the Steinhart Aquarium, these elements represent
the Academy: Space, Earth and Ocean.
These 3 icons ‘push’ the roof up, and thus create the undulating roofscape.
This roof, floating at the same height as the roof of the original
halls, formally unifies the institute. It is landscaped with native plant
species which are drought resistant and do not require irrigation once
established. The green roof extends beyond the perimeter walls and
becomes a glass canopy providing shade, protection from the rain and
generates energy through more than 55,000 photo voltaic cells in the
glass.
In the center of the Living Roof a glazed skylight covers a piazza. Much
smaller skylights distributed over the surface of the roof, allow natural
light into the exhibit space and can be automatically be opened for the
natural ventilation of the space below.
The Research activities and the storage of scientific specimens (a collection
of 18 million specimen in jars and special containers) will be
concentrated on the 5 floors facing south to the park. Additionally the
exhibit halls and the public entrance, will be oriented to the other wind
directions on the ground level. In the basement, below this floor, a large
aquarium has been located together with back for house functions of
the museum and the life support system for the tanks.
The Piazza
The piazza is the focal point of the new institute and is covered partly
with a glass roof, its structure recalling a spider web, while the center is
open to the sky. The two main aquarium tanks are positioned adjacent
to this space and connect the groundfloor with the aquarium in the
basement.
During opening hours the piazza will be used as a lunch and break-out
space, in the evening for concerts, diners and parties. A sophisticated
system of retractable fabric screens under the glass skylight assures
the comfort level in this event space. Sun and rain screens, as well as
special screens to improve the acoustics, are important features that
help to control the microclimate in the space.
Client
California Academy of
Sciences
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Architects
Renzo Piano
Building Workshop, architects
in collaboration with
Stantec Architecture,
San Francisco
Design team: M.Carroll,
O.de Nooyer (senior partner
and partner in charge) with
S.Ishida (senior partner),
B.Terpeluk, J.McNeal,
A.De Flora, F.Elmalipinar,
A.Guernier, D.Hart, T.Kjaer,
J.Lee, A.Meine-Jansen, A.Ng,
D.Piano, W.Piotraschke,
J.Sylvester; and C.Bruce,
L.Burow, C.Cooper, A.Knapp,
Y.Pages, Z.Rockett, V.Tolu,
A.Walsh; I.Corte, S.D’Atri,
G.Langasco, M.Ottonello
(CAD Operators);
F.Cappellini, S.Rossi,
A.Malgeri, A.Marazzi (models)
Consultants
Ove Arup & Partners (engineering
and sustainability);
Rutherford & Chekene
(civil engineering);
SWA Group (landscaping);
Rana Creek (living roof);
PBS&J (aquarium life support
systems);
Thinc Design, Cinnabar,
Visual-Acuity (exhibits)
General contractor
Webcor Builders

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Exhibit Spaces
The exhibit design in concept was developed parallel with the building
design resulting in a large, flat, 34 feet high flexible exhibit space on the
ground level which benefits from the natural light and ventilation
through the facades and the roof. (the space is ventilated by means of
operable vents in the glazed facades and openings at the large undulations
of the roof, where warmer air is allowed to escape during the day)
This exhibit space continues outside of the building envelope, and is
first protected by the glass canopy and then continuing in the park in
which the Academy is situated. A new aquarium exhibit is realized in
the basement, taking advantage of the absence of light for better visibility
into the tanks. The large open tanks adjacent to the Piazza are
connected to the aquarium exhibits, thus allowing natural light to penetrate
through the water into the aquarium below. Because of the need
for a highly controlled environment in the tanks they are positioned next
to the life support system spaces.
African Hall was restored and continues to display its historic dioramas,
while California Hall was replaced by a similar volume which houses the
new Auditorium as well as the Academy Restaurant.
Public Entrance
The main entrance on Music Concourse Drive was shifted about 80
feet to the northeast, to center the facility on the site. This new configuration
achieves a more compact footprint and in doing so returns one
acre of land to the Golden Gate Park.
The elimination of one driveway and landscaping the area between the
Concourse bowl and the Academy, the original formal stairs accessing
the Academy have been eliminated creating a gentle slope that leads
up to the entrance.
The new parking garage under the Music Concourse Drive has a protected
exit under the glass canopy, adjacent to the entrance doors of
the Academy.
A second entrance, from Middle Drive, passes through the Research
and Administration block, thus becoming mainly the staff entrance with
a possibility to allow public access also here in the future.
Cross section of the RCA Building
The Research, Collection and Administration Building
Only three of the five floors of the RC&A building are above grade. The
two lower floors are under the main exhibit floor level, directly adjacent
to ‘back of house functions’, such as the aquarium life support, the
loading dock, workshops etc.
The scientific library occupies the upper floor and the research departments
most of the lower 4 floors, mixed with Administrative functions.
The entire scientific specimen collection is stored between these
research and administration spaces at the facade and the flexible
exhibit floor.
The Research and Administration facility will be naturally ventilated and
naturally illuminated by employing operable windows and automatic
sun blinds, which will balance the natural light in the workspaces.
Materials
To emphasize the roof and the building as a whole, the materials used
for the new Academy are minimal. The use of color is sporadic, (e.g.
only to indicate circulation of visitors), leaving the spaces neutral in
color intentionally. The material palette is “frugal”, not rich, to make the
space strong and essential.
Light gray architectural concrete is the main material for the walls and
closed facades, apart from the restored the African Hall which features
the original limestone. The formwork tie holes have been left visible and
are used to fix exhibits.
The floors are polished concrete and the exhibit hall soffit consists of a
series of individual white acoustic panels, mounted horizontal under the
undulated roof, thus creating a “fish scaled” surface
The four glazed facades in between the more solid blocks are executed
with extra white glass, to enhance their transparency and to
improve the visual transition of the interior into the Golden Gate Park.
The roof is a hybrid concrete\steel structure with vegetation on top,
including a water “storage” layer. The roof transforms towards the
exterior into a light steel structure supporting glass panels with PV
cells.
OdN, Genoa, 28 July, 2008
Photographer: Nic Lehoux

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5
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RCA Building East
RCA Building West
Planetarium
Piazza
Rain Forest Hall
Africa Hall
Cafe
Retail
Exhibit
Labor workroom visitors
Side entrance
Main entrance
Rrainforest exterior: Inside the four-story rainforest dome, visitors can meet live rainforest residents from Borneo, Madagascar, Costa Rica, and the Amazon.
Ground floorplan
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9 3
5
9
6 7
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Photographer: Tim Griffith/ARUP
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Rainforest interior: A winding
ramp allows visitors
to explore the different
levels of the rainforest.
A 100,000-gallon
Amazon Flooded Forest
tank graces the bottom of
the exhibit.

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CALIFORNIA ACADEMY
OF SCIENCES
Engineering
and sustainability
by Ove Arup & Partners
Text
Janette Lidstone
Peter Lassetter
Eric Ko
Jean Rogers
Armin Wolski
Paul Switenki
Founded in 1853, the California Academy of Sciences is the largest
cultural institution in the City of San Francisco, one of the ten largest
natural history museums globally, and has a mission to explore and
explain the natural world.
The Academy’s new $484 million home located in Golden Gate Park
opened to the public on 27 September 2008 and its completion marks
the end of a seven year collaboration between Arup, and the architects
Renzo Piano Building Workshop and Stantec.
The visually-striking building features an undulating 2.5 acre living roof
with a perimeter steel canopy supporting photovoltaic cells, a large
glass skylight supported by a tensile net structure, a freestanding 90foot
diameter planetarium dome, five separate iconic aquarium tanks
and a 90-foot diameter glazed dome housing a rainforest exhibit.
Come inside and learn about the engineering and consulting solutions
that made this new San Francisco icon a reality.
STRUCTURAL SOLUTIONS
From the ground floor up, the Academy appears as four, rectangular
cornerstone structures reminiscent of the old Academy arrangement.
These structures contain the research, collections and administrative
areas, exhibits, retail, dining and conference facilities.
The main structure of these buildings consists of concrete shear walls
and columns with concrete flat plate floors on a 24-foot x 24-foot grid.
From the main podium level, two 90-foot diameter domes rise to house
the planetarium and rainforest exhibits. Glass walls and an undulating,
2.5 acre, native green roof - representing the seven hills of San Francisco
- enclose the volume between the cornerstone structures. Included
within are the two large spherical volumes (the rainforest and planetarium),
a 6,000 square foot glass piazza and 38,000 square feet of flexible
exhibit space. As the executive architect Renzo Piano described it,
the green roof design is like lifting up a piece of the park and putting a
building underneath it. The rainforest and planetarium form two of the
seven mounds that represent the topography of San Francisco.
The living roof
The undulating 2.5 acre ‘living roof’ blanketed with 1.7 million native
California plants is one of the key building features. With seven ‘hills’
mimicking the seven hills of San Francisco, the roof structure consists
of a grillage of curved steel beam sections – some spanning up to 96feet
- that support a contoured concrete slab. The curved steel beams
form a structural skeleton whose concrete skin was applied from
above (with the aid of temporary timber formwork) to achieve a carefully
contoured finished surface.
The combination of complex geometry, architecturally exposed steel
and necessary seismic detailing made the steel connection design a
challenge. Three-dimensional computer modeling techniques were
used extensively to create connection details that were both structurally
and aesthetically acceptable. Once developed, these computer
models were provided to the steel fabricators who then prepared their
own computer models for final detailed shop drawings.
The piazza skylight
At the center of the roof is a curved 72-foot x 98-foot glass skylight
supported by a steel tensile structure. This structure consists of two
nets of threaded stainless steel rods, each with a 6-foot x 6-foot grillage.
Vertical steel pipe struts connect the two nets at the nodal points.
The connections at these nodes are made by an articulated cast stainless
steel connector. This allows for all connections with varying geometry
to be made with a single connector type and allows for required
rotation.
The tensile structure is then supported by a perimeter ring truss which
transfers lateral forces into the surrounding roof structure. The glass
panels in the skylight are 6ft x 6ft triangular panels with three-point
support, using both patch and point support. These triangular panels
provide for a faceted geometry which allowed for a significant cost
reduction as compared with the alternative using doubly curved glass.
The exhibit tanks
The museum features five new aquarium tanks, including a Philippine
coral reef tank containing the largest living coral reef exhibit in the
world, a California coast tank featuring native California marine life, a
swamp tank including a flooded Amazonian rainforest floor with walkthrough
acrylic tunnel, gar tank and a penguin tank. The relative complexity
of the tank geometry and openings to receive acrylic panels
provided for extensive concrete detailing. Concrete water tightness is
addressed by using a mix design with a Xypex crystalline admixture
and by careful detailing of construction joints. Corrosion resistant
MMFX-reinforced steel was used in all concrete that is in contact with
water.
The rainforest exhibit
The rainforest exhibit features a 90-foot diameter glazed dome (bolla)
and a series of winding ramps which lead visitors through various rainforest
habitats. The bolla structure consists of an interior glazed dome
approximately 90-feet in diameter. Glass panels are point supported by
cast spider brackets, which are supported by a grillage of steel pipes.
Lateral stability is provided by tension rod bracing. A concrete ring
transfer beam at the first level supports the dome structure.
The rainforest ramp construction consists of a central steel pipe with
concrete fins that support the walkway. The ramp pipes are filled with
concrete to improve vibration performance. The sinuous geometry of
the ramps lent itself to fabrication by a steel fabricator that specializes
in fabrication of roller coasters.
The planetarium
The planetarium dome structure consists of a truncated sphere
approximately 90-feet in diameter. An inner projection screen dome is
75-feet in diameter. The planetarium will include an extremely precise
digital projector that will not only present the typical star displays, but
also provide live feeds from NASA’s planetary missions and other
space ventures. The outer dome structure is made up of steel pipe and
wide flange sections acting as both meridian and parallel elements.
The dome supports a GFRG exterior cladding system as well as the
inner projection dome. The lateral system consists of chevron diagonal
bracing.
SEISMIC INNOVATION
The site of the California Academy of Sciences lies within 10 miles of
the San Andreas Fault, and in its lifetime is likely to be subject to very
strong ground shaking. A standard building code approach required
the use of ground anchors on the building to prevent the Academy
from overturning during a seismic event.
Pushing the boundaries of conventional design, Arup structural engineers
agreed that instead of the building aggressively resisting an
earthquake by tying it down, the structure should work with the seismic
forces, dissipating the energy in an elegantly simple manner – through
rocking at the foundations.
This is not a new idea. Many engineers have hypothesized the benefits
of allowing buildings to “rock”, but few have implemented it. The seismic
concept for the Academy can be considered similar to the structure
of a table. The four wings of the building act as table legs and the
roof as the table top. The roof and ground floor slab tie the table legs
together to ensure the building acts as a whole. This roof comprises a
5 inch concrete slab over steel beams typically supported on a 48-foot
x 24-foot column grid, except in the dome areas, where beams arch
up to 96-foot intervals in the north-south direction. During an earthquake,
lateral forces will be transferred through the roof and floor slabs
in to 18-inch reinforced concrete shear walls in the four wings and
basement.
The interaction between the four wings and the roof was essential to
the seismic design. The roof structure is reasonably flexible, largely due
to the curved dome structures with glazed penetrations and the large
central space for the elegant piazza glass canopy.
Photographer: John McNeal
Cross section Piazza
Cross section Rain Forest Hall, ventilation, day- and artificial light
CFD model with ventilation openings
Piazza

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The living green expanse of the roof must roll and expand with an
earthquake to accommodate any differential movements between the
wings without compromising its stability.
Arup’s seismic concept was keenly embraced as it was in tune with the
green philosophy of the building design. The idea of the Academy
‘dancing with nature’ was appealing, but first it had to be thoroughly
investigated. A performance-based approach was undertaken to validate
the design concept and quantify the performance of the new
Academy without ground anchors. Non-linear dynamic time history
analyses were performed on a three-dimensional finite element model
using advanced simulation software, CEAP (2004). Essentially the new
Academy was ‘virtually-tested’ for an earthquake.
The performance of the building was shown to meet code level standards
and was improved through allowing the building to rock at its
foundation. Approximately $2 million was saved from the construction
budget by alleviating the need for ground anchors.
SUSTAINABILITY AT ITS BEST
Close collaboration between Arup, the California Academy of Sciences
and the architect, Renzo Piano Building Workshop, has yielded innovative
strategies to help preserve the natural integrity of Golden Gate
Park, conserve water and energy, reduce pollution and maximize natural
ventilation and light.
Arup has also taken a leading role in assisting the Academy with its
application to achieve a Platinum rating in Leadership in Energy and
Environmental Design (LEED) from the U.S. Green Building Council.
While many museums turn their backs on nature, the Academy is
embracing and attempting to embody it in both form and function.
With a projected 1.6 million visitors annually, the building itself will be an
exhibition - an educational tool for the general public.
The living roof
The new roof of the Academy comprises more than two and a half
acres of California native plants. Due to the undulating nature of the
roof, the 1.7 million plants occupy a diversity of exposures, slopes and
biological interactions. To assess which plant species could thrive in
the climate regime of northern California - including a variety of exposures
- slopes and nutrient/water combinations, the roof of the former
building on the site of the new Academy was used to assess the viability
of three dozen different plant species and several systems for soil
mixtures and stabilization and drainage.
A full-scale mock-up of a section of the roof was constructed to prototype
and demonstrate not only the techniques required to bend the
steel to achieve the significant degree of slope necessary for the roof’s
form, but then to plant the section to study plant species growth and
associated fungi below ground, and the native insect and bird species
attracted to the plants. The undulating roof aims to mimic the seven
hills of San Francisco. Functionally, it helps to serve as a chimney so
when hot air in the Academy rises; the public spaces will be naturally
ventilated. It will also serve to save energy (keeping the interior temperature
10 degrees cooler than on the roof), conserving water through
the use of reclaimed water in a micro-irrigation system. By addressing
storm water management issues, 3.5 million gallons of rainwater won’t
flow into the storm drains of San Francisco, but will be captured on the
Academy’s roof.
Renewable energy
The perimeter of the roof is bordered by 60,000 photovoltaic cells. This
system will not only provide cover and modulate light for visitors, but
provide over 220KW of energy annually. That is the equivalent of preventing
400,000 pounds of greenhouse gases emissions entering the
atmosphere, and would be the equivalent of planting 340 trees.
The photovoltaic cells will generate 5% of the building’s total energy.
The energy produced by the photovoltaic cells will be highlighted and
demonstrated on the publicly-accessible roof deck. In addition, tours of
the building will be offered to highlight and demonstrate how the building
works, the materials used and performance of conservation
approaches.
Indoor environmental quality
By employing natural daylighting and ventilation, high-efficiency electric
lighting, and commissioning, the Academy will use 30% less energy
than federal and state requirements. The glazed transparent facades
and roof sections of the building will allow daylight to be filtered into the
office, research and exhibition spaces, helping to reduce energy use
and heat gain from electric lighting. Operable windows, daylight and
views in 75% of all regularly occupied research and office spaces
ensure thermal comfort, and the health and productivity of staff and
volunteers. The public spaces have 90% with daylight and views.
Lighting controls include dimming - linked to the external light level - to
ensure that a minimum of electric light is used at all times. As part of
the low energy design strategy, the Academy plans to minimize the use
of mechanical systems for ventilating and cooling internal spaces. The
exhibit area will be naturally ventilated.
The roof shape in the form of ‘hills’ provides the height differences
required for stack driven (warm air rises) ventilation on calm days. On
days with some wind, the roof hills generate a negative pressure at the
top, to provide driving pressure for airflow. The open offices will be naturally
ventilated. The building shape and materials are designed to be a
climatic filter, limiting the solar gain and cooling/heating requirements.
Easy to open windows will be used so that occupants still have control
over their local environment. Natural daylight will be accomplished with
the glazed facades, the roof design, and lighting controls.
Water
Use of reclaimed water and low-flow fixtures will mean that the Academy
will use 20% less water than required by code, and reduce reliance
on municipal potable water for wastewater conveyance by 85%. The
building is plumbed for the use of recycled water, which will be provided
by the City of San Francisco. Recycled water will be used in the
bathrooms and in the life support systems to backwash the aquarium
filters.
Arup has also developed water systems for the aquarium so that energy
and potable water use are minimized. A number of strategies have
been employed for the ‘greening’ of the life support system of the
aquarium. They include:
• Emulating natural systems with removal of waste
• Adjusting water clarity to approximate nature (versus having ‘gin
clear’ water)
• Minimizing energy use through mechanical design (with big pipes,
small pumps, equipment locations following pipe layouts, use of variable
speed pumps etc)
• Minimizing the use of potable water by using reclaimed (gray) water
to backwash recovery filters; minimizing water discharge to sewers
with backwash recovery systems; and closed versus flow-through systems.
The entire aquarium industry will benefit from the technologies being
employed at the Academy.
Building resources
The Academy’s original building was taken down, except for outer
walls of Africa Hall. More than 80% percent of the materials in the original
building have been recycled, including stone, wood, concrete and
glass.
The stone was crushed and included in a number of public building
and construction projects around the Bay Area. More than 9,000 tons
of concrete went to the Richmond Roadway project site, 1200 tons of
metal were recycled and 120 tons of green waste were recycled for
landscaping on-site.
Building materials including non-virgin or renewable resources that feature
high recycled content, low embodied energy, long life span, and
no or low VOCs were used in the construction of the new Academy.
PROTECTING THE ACADEMY FROM FIRE
Innovative suppression system
The Research Collections & Administration (RC&A) storage for the California
Academy of Sciences includes approximately 6 million scientific
specimens in small containers, many of which are ‘archival’, and more
The 90-footdiameter planetarium dome is cantilevered out over the Philippine Coral Reef tank-the world's deepest
living display of corals.
Photographer: Tim Griffith/ARUP
Air movement and temperature as ribbon model
Evacuation model for Rainforest Dome
Fire modelling for Rainforest Dome
Protecting the academy from fire
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Exhibit Hall
CFD Model Geometry

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than 100 years old. A majority of these specimens are preserved in a
70% - 75% alcohol solution. The total amount of flammable liquid is
estimated at 100,000 gallons. This volume of flammable liquid in a
large assembly building can be a cause for concern. In addition, the
specimens are stored in a special high-density shelving system (compactors)
that slide on tracks for access.
Since the Academy is a ‘working’ scientific facility, it was important that
the specimens remain readily available to the researchers. Off site storage
was not an option. In order to allow an unlimited amount of flammable
liquids to be stored in the Academy, separate buildings (flammable
liquid storage warehouses) were created within the main building
with the help of area separation (fire) walls.
Due to the special hazard and configuration (flammable liquids in compactor
shelving units), the design of an appropriate automatic fire suppression
system was a particular challenge for Arup’s fire engineers. In
addition, a secondary containment of spills and the fire suppression
water were required. Since no published protection guidance existed
for this special arrangement (high-density storage, low ceiling clearance,
flammable liquids in glass and plastic containers), full scale fire
testing was proposed using a mist deluge system.
Perfect timing
The Academy also contains a unique multi-level rainforest exhibit. This
exhibit is enclosed in a glass sphere and will create a humid Amazonian-like
environment with a water-filled pond on level one and trees and
vegetation extending through level two up to the third level. The visiting
public will be able to enter the glass sphere at level one and circulate
throughout the three levels via a spiral open ramp system.
The building code does not normally permit three levels to be atmospherically
interconnected without a smoke exhaust system. Since the
glass sphere is located within a building, a smoke exhaust system was
not feasible. An alternate method of construction design was developed
by Arup using performance based fire engineering.
With the help of computer modeling, a timed egress analysis was conducted
to verify the safety of the egress system of the rainforest exhibit.
The available safe egress time was established based on computer fire
consequence modeling and compared to the required safe egress time
determined using a computer egress model.
The quantitative tenability criteria and the probable fire scenarios were
established, and then computer fire consequence modeling was conducted
to determine the available safe egress time. The required safe
egress time was determined by performing a timed egress analysis.
This included an estimation of the time at which the occupants
become aware of the fire incident, as well as the delay time for occupants
to start evacuation and the time involved (including travel time
and queuing) after the decision is made to evacuate.
The latter was determined using the computer egress model STEPS
(Simulation of Transient Evacuation and Pedestrian movementS). The
required safe egress time included a safety factor that accounts for the
uncertainty inherent in human behavior and movement. Mobility
impaired occupants were also modeled.
MECHANICAL ENGINEERING
The California Academy of Sciences is a major cultural and environmental
icon within the city of San Francisco and Arup’s mechanical
design was strongly influenced by the sustainable strategies laid out for
the building. However, minimizing energy consumption while providing
superior indoor environmental quality was a difficult challenge. Arup
needed to research and specify a diverse suite of mechanical solutions
and equipment to condition and ventilate the many spaces within the
Academy while meeting the performance criteria to achieve a Platinum
LEED rating.
Main exhibit floor climate control
The 38,000 square-foot, main exhibit space was a challenge for Arup
to ventilate and condition. The goal to maintain monolithic, sheer surfaces
coupled with the desire to display the geometry of the green roof
above meant Arup’s mechanical engineers could not use traditional
overhead air systems.
Instead, Arup’s approach was to take advantage of San Francisco’s
mild climate, using natural ventilation with supplemental heating and
cooling via a radiant floor slab. Solar gains are minimized by the roof
overhang and by motorized sun shades protecting some of the glass
walls and canopies.
Natural ventilation does the majority of the space cooling, while the
radiant floor delivers all space heating requirements and also provides
supplementary cooling. The massive exposed concrete surfaces serve
as a thermal capacitor, reducing peak heating and cooling loads and
assuring space comfort is maintained. Sun shades on the east and
west glass walls and on the north canopy are activated when solar
intensity is high, unless wind speed is excessive.
High and low level ventilation openings are located in the glass walls
surrounding the exhibit areas. During cold weather high level openings
provide background ventilation and minimize low level drafts. During
warmer weather, high and low level openings work in tandem to maximize
air flow and limit space temperatures. Roof vent hatches are also
provided at the high points above the rainforest and planetarium
exhibits. All openings are automatically controlled to adjust space airflow
and temperature.
On a still day, airflow is generated by stack-effect (warm air rising) generated
by the height difference between facade openings and the roof
vents above the rainforest and planetarium. On a day where some
wind is present a negative pressure is generated at the roof vents and
drives the airflow, regardless of the wind direction.
Exhibit space temperatures and wind conditions drive the ventilation
sequence. Wind direction determines which banks of dampers operate,
and the space temperature dictates damper position. Vents can
be overridden by several means. They move to a more fully open position
when CO2 concentration exceeds the space setpoint or when
the humidity level exceeds its allowed upper limit. Some or all of the
vents close if conditions are right for floor condensation, if wind speeds
are excessive, or if rain or fog is present.
High level vents are kept open at night if the previous day’s temperature
was high if the nighttime air is cool and if the slab is warm.
Powerful exhibit lighting is located above the coral reef and rainforest. If
the vents cannot be opened due to one of the override conditions, high
level temperatures rise and trigger the lighting control system to shut
off lights, thereby preventing overheating of the space and nearby
glass.
Complex analyses were necessary to hone the system design and
prove that comfort conditions would be maintained throughout the
Academy’s operating hours. Using Computational Fluid Dynamics
(CFD), Arup proved that on a summer’s day (79°F), with the floor slab
at 68°F, the occupied zone’s operative temperature is expected to be
in the mid-70s and the average air velocity to be 35 feet per second.
Likewise, the CFD studies proved the exhibit area will be maintained at
an average temperature of 69°F and air velocity of 60-feet per minute
in the winter. For both design conditions, these parameters fall well
within comfort requirements.
The radiant floor
Approximately 100,000 linear feet of tubing runs within the 38,000
square feet of concrete slab. Manifolds are located at the first level of
the three-level basement. The system is broken into nine independent
temperature control zones, so nine sets of valves, pumps and accessories
have been located in the mechanical rooms on the first basement
level.
The floor operates in cooling mode only when the exhibit area temperature
is above setpoint or when the outdoor air temperature is above
77°F and rising. In cooling mode, the return water temperature is fixed
at 68°F. When the outdoor air temperature falls below 64°F the radiant
floor switches into heating mode.
The water temperature modulates between 75°F and 90°F as the outdoor
temperature drops to the winter design condition. The system
changes over from heating to cooling via simple modulation of two-way
valves – one at the tertiary chilled water (radiant) loop and one at the
associated hot water heat exchanger.
The Water Planet exhibit features an ever-changing array of aquarium tanks set into curvilinear
walls that evoke ocean waves.
Summer temperature contours - section through Exhibit Hall, Detail Summer velocity vectors - section through Exhibit Hall, Detail
Summer temperature contours - Plan view at 3.6ft above floor level
Summer temperature contours - Section through Exhibit Hall Winter velocity vectors
Exhibit Hall without Piazza
The new African Hall closely resembles the original hall, a longtime San Francisco favorite.
It is now also home to five live animal displays, including African penguins at the
end of the hall.
Summer velocity vectors - Plan view at 3.6ft above floor level
Planetarium Rainforrest
Photographer: Tim Griffith/ARUP

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