MARCH 14, 2016
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Stanford Energy System Innovations
Stanford University, Calif.
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ROGER FRICKE
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MATT
Construction
ANDY FRY
Chief Operating
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Magnusson
Klemencic
Associates
LAWRENCE A.
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MARK HASSO
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American
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ENERGY/INDUSTRIAL l Submitted By ACCO Engineered Systems
Stanford Energy System Innovations
Stanford, Calif.
REGION California
PROJECT TEAM
OWNER Stanford University
LEAD DESIGN FIRM/MEP ENGINEER Affiliated Engineers Inc.
CONTRACTOR Whiting-Turner
STRUCTURAL ENGINEER Rutherford + Chekene
CIVIL ENGINEER BKF Engineers
ARCHITECT ZGF Architects
MEP CONTRACTOR ACCO Engineered Systems
CONTROL SYSTEM Johnson Controls Inc.
To university engineers, the Stanford Energy System Innovations (SESI)
project represents nothing less than a revolution in the way campuses in
the U.S. should be heated and cooled. Stanford University eagerly uses
SESI to demonstrate to corporate, municipal and other school officials
that they, too, can save energy, reduce water use and drastically reduce
greenhouse-gas emissions.
The $485-million effort—in fact, four projects in one—replaces an
aging 50-MW natural-gas-fired cogeneration plant with a new heatrecovery system to provide heating and cooling to the campus. A new
80-megavolt ampere electrical substation brings electricity from the grid
and direct-sourced renewable-energy suppliers. Crews also converted
155 campus buildings from steam to hot-water distribution and installed
a 22-mile-long network of new pipe. “You could take any one of those
four projects and it would be a significant engineering challenge,” says
Krista Murphy, principal with lead design firm Affiliated Engineers Inc.
(AEI). “We were tackling all of those at the same time.”
Since completion last April, facilities managers have flocked to study
SESI. “We’ve had overwhelming demand—tours are booked months in
advance,” says Joseph Stagner, executive director of sustainability and
energy management at Stanford. Leaders from other universities, the
President’s Council of Advisors on Science and Technology and even
France’s ambassador have made the pilgrimage to SESI.
Change of Heart
To learn how Stanford cut campus energy use by 50% and dropped its
greenhouse-gas emissions by 68% in just two and a half years, visitors
start at SESI’s heart—the 125,614-sq-ft central energy facility (CEF),
located on the west side of the campus. The CEF houses what Stanford
calls the star of the show: three heat-recovery chillers—the largest in the
U.S.—that strip waste heat from 155 campus buildings via a closed
chilled-water loop and use it to preheat a separate closed hot-water loop
that distributes heat to the same buildings.
From dorms to hospitals to sports facilities, a variety of campus structures
provides a huge heat-recovery potential. The system captures 57% of building
waste heat, reusing it to meet 93% of campus heating needs. For most of the
year, the system precludes the need for cooling towers to discharge excess
heat, which reduces water consumption on campus by 15%.
Each heat-recovery chiller (HRC) provides a 2,500-ton cooling
CHUCK JABLON
Senior Executive
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Skanska
USA
ALEISHA JAEGER
Construction
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Gilbane
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MICHAEL KAUFMAN BARRY L. LACY
Partner
Claims/Work Zone/
Audit Engineer
Goettsch
Partners
Louisiana
Dept. of
Transportation
& Development
GATHERING SPACE Tour groups from all over the world congregate at the
staircase in the main courtyard to learn about SESI. The stairs lead to a twostory administration building that wraps around a hot-water storage tank.
capacity for chilled water and simultaneously can produce 40 million
BTUs of heat per hour. The HRCs send out chilled water to the
campus at 42°F, which returns at 56°F to 60°F. The heat removed
from the chilled water as it is cooled back down to 42°F reheats
spent hot water (which returns to the CEF from campus at 130°F)
back up to 160°F to 170°F to supply heating.
Additional efficiency results from the switch from steam heat to hot
water. Line loss of up to 20% in the old steam system dropped to under
4% with hot-water piping. The switch also saves the school several
million dollars a year in operations and maintenance. Further, the
school’s previous cold storage existed in the form of ice. “Chillers take
about 25% more energy to make ice than they do cold water,” he says.
By using out-of-date systems that create steam and ice, “America has
been hitting it with a sledgehammer because energy was so cheap, and
ROBERT MATTHEW JOHN A. SPORIDIS
NOBLETT
Managing Principal
Partner
Vanderweil
Behnisch
Architekten
Engineers
DAVID WESSIN
Vice President
Safety and Loss
Control
PHOTO LEFT BY TODD QUAM, COURTESY JOHNSON CONTROLS;
TOP RIGHT BY MATTHEW ANDERSON; BOTTOM RIGHT BY ROBERT
CANFIELD
Coastal
Construction
Group
enr.com March 14, 2016
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control-system subcontractor Johnson Controls to develop
it into a viable commercial product. Dubbed the Central
Energy Plant Optimization Model (CEPOM), the algorithm
performs a 10-day look-ahead every 15 minutes,
considering campus loads, weather patterns, price of
electricity, available equipment and many other factors. It
then computes the optimal dispatch plan, and it can even
be used as an “autopilot” to run the plant. The program
performs about 30% more efficiently than what a human
can do, Stagner says.
Led by contractor Whiting-Turner, construction began in
2012. While one crew assembled the complex plant, another
worked its way through the active campus to install 22 miles
of new pipe.
Hot-water pipe can be installed more quickly and at less
expense than steam pipe, which needs to be buried to a 15-ft
depth—below all other utilities—to reduce the risk of heat
damage from steam leaks. By contrast, the pre-insulated
hot-water pipe system, sourced from Denmark, was buried 3
ft to 5 ft below the surface, without the need to construct
concrete vaults or anchors. As a result, crews installed the
system in two and a half years, instead of the 10 years it would
have taken to replace the steam pipes. The old steam pipes
remain abandoned in place.
To convert each campus building from steam to hot water,
the team designed a standardized heat-exchanger skid, with
only the capacities varying by building. “This allowed the
long-lead equipment to be ordered directly by Whiting-Turner
before the mechanical subcontractors were hired. The
prefabrication allowed building shutdowns to be much shorter,
with less disruption to research and building occupants,” says
Damon Ellis, Whiting-Turner vice president.
Converting 155 buildings—while the CEF was still under
construction and the cogen plant continued to provide steam
heat—presented the team with a logistical puzzle. To solve
this, AEI turned to regional heat exchangers—also skidmounted—which converted the cogen’s steam to hot water.
Then, a mini hot-water loop transported the water to each
pre-converted building. “Use of the regional heat exchangers
ENERGY TRANSFER Three heat-exchange chillers (top) strip waste heat from the chilledgave us the single most important ability to execute this job,”
water-loop return and use it to reheat partially the hot-water-loop return. The chillers work in
says Michael Bove, principal with AEI.
harmony with thermal storage tanks and other components (bottom).
As part of the new substation, crews placed nearly 40
miles of copper wiring underground. Four miles of overlap between the
that’s how things evolved.”
wiring and piping allowed crews to work more efficiently and reduced
The CEF’s thermal storage system contains two 5-million-gallon tanks
campus disruption.
to store cold water and a 2.3-million-gallon tank for hot water. The tanks
While some may balk at the $485-million price tag, the project was
double as reservoirs for power, allowing flexibility to operate the heat“completely driven by astute economics that allow this university to have
recovery chillers and other equipment during times of lower energy pricing
such a well-crafted and well-performing endowment,” Stagner says. “It’s
or when outside air temperatures are optimal. For example, when it’s hot
smart business.”
during the day, excess heat can be converted and stored as hot water,
Stanford carefully studied multiple options, including replacing the
instead of being rejected out of evaporative cooling towers, and then used
natural-gas cogen plant, and found that the heat exchange system would
during the cooler nighttime hours.
actually cost $459 million less over a 35-year life cycle while providing
A two-story administration building surrounds a small plaza, which has
environmental and efficiency benefits.
the hot-water thermal storage tank at its center. The tank, painted Stanford
“One of the things that we’ve talked to other universities about is to not be
red and lit at night, evokes a beating heart at the center of a “system that
too taken aback by the enormity of this project,” Bove says. “Any university
pumps energy around the campus,” says architect Joseph Collins, partner
could do bits and pieces that have happened here. Stanford just had the
with ZGF Architects.
vision and ability, both financially and scope-wise, to do it all at once.”
Large expanses of glass provide transparency into the areas that house
And the technology continues to improve. Stanford’s real estate
the HRCs and other mechanical equipment. Vivid colors clearly demark the
division retained AEI and architect ZGF to design a new, 1.5-million-sq-ft
complex piping in a way that provides visual clarity to students and visitors.
campus to house 2,300 Stanford employees in Redwood City. Due to
For example, light-blue piping indicates the cold-water loop returning from
efficiencies in the new buildings and their heat exchangers, the system
campus, while dark blue pipe contains re-chilled water after the heat has
can operate with water heated up to just 110°F, instead of the 160°F
been removed. Similarly, hot-water pipes are painted orange and red.
needed to heat the main campus. In fact, the team estimates the heat
“We do many heat-recovery chillers, but I don’t think we have any that
pumps at the new facility will operate at 0.7 KW per ton, instead of the 1.3
are showcased the way this is, with glass surrounds and strong colors,”
KW per ton measured at SESI.
Murphy says. “All of it tells a story, even at the equipment level.”
“That’s the evolution of this,” Bove says. “As the temperature comes
To control the complex system, Stagner spent months programming
down, the heat-recovery equipment gets more efficient.” n
a control “brain” that models, operates and verifies performance
By Scott Blair
efficiency at the facility. After patenting the system, Stanford tasked
Excerpted from Engineering News-Record, March 14, 2016, copyright by BNP Media II, LLC. with all rights reserved.
This reprint implies no endorsement, either tacit or expressed, of any company, product, service or investment opportunity.
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PHOTO TOP BY MATTHEW ANDERSON; IMAGE BOTTOM BY AEI
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