`House Air` system improves vivarium air quality

School HVAC
The following article was published in ASHRAE Journal, May 2007. ©Copyright 2007
American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. It is
presented for educational purposes only. This article may not be copied and/or distributed
electronically or in paper form without permission of ASHRAE.
‘House Air’ system improves vivarium air quality, reduces energy loads and is architecturally expressed at the Life Sciences Institute.
University Laboratory System
By Ronald W. Henning, P.E., Associate Member ASHRAE
T
he University of Michigan is one of the premier research institutions in the United States. In May 1998, the university embarked
on a study of the rapidly developing fields of the Life Sciences by
forming the President’s Commission on the Life Sciences, which led
to the enhancement of collaboration and exchange of ideas across
a range of academic and medical disciplines. To achieve the desired
collaboration, the northeast corner of the university’s central campus
required a physical transformation. As a result, the Life Sciences
Institute was created to foster basic and translational research.
The Palmer Drive Development is a
complex of buildings including the Life
Sciences Institute (LSI), the Undergraduate Science Building, and Palmer Commons. It also includes a 1,000 car parking
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structure; a 100,000 ft2 (9290 m2) plaza
and walkway system; and the creation
of a pedestrian bridge that spans across
a major city thoroughfare. The Palmer
Drive Development creates a physical and
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intellectual “bridge” across what used
to be a “chasm” of traditional academic
studies, medical research and the education of future scientists.
The LSI building presented the challenge of creating the right work environment for the building using a mechanical
and electrical system that would be flexible enough to accommodate revisions
and upgrades over the life of the building.
It was also important that the building
met the energy efficiency requirements
of the university.
Life Sciences Institute
The LSI is a 235,000 ft2 (21 831 m2)
biomedical research facility consisting of
six floors and a mechanical penthouse.
The building houses three major funcAbout the Author
Ronald Henning, P.E., serves as the chief mechanical engineer for SmithGroup’s Science & Technology
Studio in Detroit. Henning won an honorable mention for the 2007 ASHRAE Technology Awards.
May 2007
tional groups; 43,400 ft2 (4030 m2) of vivarium space located
on the lowest level of the building, 135,000 ft2 (12 540 m2) of
laboratory and laboratory support spaces on the third through
sixth floors; and 25,000 ft2 (2320 m2) of office/interaction
spaces distributed across the second through sixth floors. Major
mechanical and electrical spaces are located on the second floor
and penthouse floor of the building.
ing the operating static pressure of the exhaust system.
The two air-handling units serving the laboratory/laboratory
support spaces each contain two supply fans and the supply
ductwork is cross connected at each of the floors. This cross
connection of the supply ductwork provides a common supply
duct from the two air-handling units and allows for redundancy
in the system with the four total supply fans.
One of the four air-handling units serving the vivarium is a
Central Plant Heating and Cooling
redundant unit and the system can operate at 100% capacity
The LSI building in the Palmer Drive Development receives with only three of the units in operation. However, an analysis
steam from an existing central power plant at two pressures, 40 of the system energy use indicated that the normal control oppsi and 9 psi (276 kPa and 62kPa). All condensate is metered eration for the system is for all four units to be in operation at
and returned to the central power plant.
all times. This allows each unit to operate at a reduced capacity
Discussions with the university and the initial analysis of the which results in less total operating fan energy than if only three
Palmer Drive Development established that a central chilled units were operating at full capacity.
water plant that could be expanded to include future buildings
The design consideration for the laboratory/laboratory support
would be more efficient and cost effective than individual exhaust air systems needed to be flexible and include redundancy.
chillers at each building. The
The resultant design allowed
design resulted in the chiller
for a four exhaust fan group for
plant being included as part of
each of the lab floors and for
the Palmer Commons Building
the vivarium. Separate exhaust
and included multiple electric
risers for each floor extend up
to the penthouse, through the
centrifugal chillers. The plant
energy recovery coils and then
has a maximum capacity of
out to the associate exhaust fan
6,000 tons (21 100 kW) and
delivers 42°F (5.6°C) chilled
group located on the roof. Each
water via a primary-secondsystem was designed to operate
ary piping system and through
on three of the four fans set at
underground tunnels.
maximum load with the fourth
fan in each group as a redundant unit. This would allow the
Design Considerations
systems to be maintained with
The building ventilation system is designed so that each of
no loss in capacity or operation
the three major function groups
on any of the lab floors.
in the building can operate inThe air-handling units
‘House air’ system minimizes exhaust and energy use.
dependently of each other for
serving the office/interaction
maximum flexibility. There are two air-handling units (25,000 spaces, are return air type units and use enthalpy control to
cfm [11 798 L/s] each) for the office and general building areas; modulate the outside air dampers, in addition to CO2 (carbon
two air-handling units (135,000 cfm [63 706 L/s] each) for the dioxide) monitoring. Using the CO2 monitoring allows units
laboratory and laboratory support spaces; and four air-handling to adjust the amount of outside air being introduced into the
units (25,000 cfm [11 798 L/s] each) to serve the vivarium spaces whenever CO2 rises above the prescribed limits.
space. All the air-handling units are variable air volume type
All motors for the air-handling units, as well as the main
with chilled water cooling coils, pumped hot water heating chilled water and heating hot water pumps, are operated through
coils, minimum 65% efficient filters and steam humidifiers to variable speed drives.
maintain proper relative humidity levels within the space.
Two separately pumped perimeter heat systems divide the
The laboratory/laboratory support and vivarium air-handling building into north and south zones to match the major buildunits are 100% outside air design with glycol runaround energy ing exposures. Each perimeter system water temperature is
recovery coils in the air-handling units and in the respective controlled, based on the outside air temperature, via a high
exhaust streams for these systems. A bypass around the exhaust limit override at each above-grade floor on the south zone. A
side energy recovery coils allows the exhaust air to bypass the separately pumped hot water heating system provides reheat
coils whenever the energy recovery system is not active, reduc- to the VAV supply valves.
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Figure 1: Typical open holding animal room control system.
A heat recovery system is part of the design to reduce heating
loads in the winter and electric cooling loads in the summer
on the 100% outdoor air systems. A pumped glycol runaround
coil loop was determined to be the best option due to space
constraints because of the distance between airstreams and cross
contamination concerns with the laboratory exhaust. Annual
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savings are estimated to be $144,000 based on 2001 energy
rates with an average airflow of 200,000 cfm (94 380 L/s) for
the laboratory and 75,000 cfm (35 392
L/s) for the vivarium. The resulting simple
payback on the increased project cost was
just over six years.
benefit of not requiring maintenance staff to enter the vivarium
space and was designed to improve the quality of space for the
staff and animals, while minimizing energy
consumption and maintenance expenses for
the systems with the highest operating cost
in the building.
The ventilated animal holding cages are
Vivarium Space Design
directly connected to the building’s HVAC
LSI’s vivarium uses a house air system
system, with laboratory airflow control
that is believed to be the first operational
valves controlling the supply and exhaust
Iris Dampers
system of its kind in the U.S. University
air. Each supply control valve includes
criteria established the vivarium design
a reheat coil to control the discharge air
to be based on a ventilated cage rack systemperature into the animal cages within
tem. The house air design was compared
the racks. An exhaust air valve is also conagainst the manufacturer’s system that
nected to the rack to ensure a slight negative
Inline Thermostat
Reheat Coil
included individual supply and exhaust
pressure at the cages.
Valve
fans placed on top of each cage rack to
This system also minimizes the quantity
ventilate the individual cages in the rack.
of ventilation air required in the animal holdThe supply fan would generally draw
ing room, since a specific quantity of air is
delivered to and extracted from each rack,
room air as the ventilation air for the Figure 2: Barrier rooms.
rather than turning over large volumes of
animal cages and the exhaust fan would
either discharge back into the room or to an exhaust duct. The room air as required with traditional design approaches. It also
house air system eliminated the fan noise in the rooms, has the allows the room temperature to be controlled by the technicians
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working in the room since the temperature within the animal cages is controlled
independently.
A manifold of racks in a room on a
common supply and exhaust air valve
enables each project to be able to use conventional air valves, which reduces cost,
while providing improved temperature
control and monitoring. This approach
reduces maintenance costs, and allows
for maintenance access from outside the
holding areas, while maximizing space
use within the rooms.
Another positive feature of the
scheme is that it eliminates the need
for two bio-pack fans on top of each
rack—one for supply and one for the
exhaust from the cages. Without the
fans, the racks are lighter and easier to
move, reducing the potential for workrelated injuries. An additional benefit is
that both room noise and noise in the
racks are reduced. The elimination of
any fan noise within the animal holding
rooms improves the environment for
the animals.
The system also provides better isolation between the room and the air in
the animal cages, resulting in a cleaner,
more odor-free environment, making
the vivarium staff much happier with
their working conditions. It is clear that
the animals also like this innovation.
Based on over one year of operation,
the reproductive rate for the animals in
this vivarium is considerably higher than
other vivariums on campus.
Laboratory/Laboratory Support
Space Design
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All laboratory and laboratory support
spaces are provided with tracking VAV
supply and exhaust air valves to maintain
a proper negative pressure relationship
with adjoining office and corridor areas.
Fume hoods for the laboratory spaces
are located in alcoves adjacent to the
open laboratory spaces. This creates a
localized area for control of the fume
hoods that is separate from the open
laboratory spaces. The fume hoods were
designed as VAV-type with sash position
sensors to control the exhaust airflow
through the hoods.
Operations and Maintenance
All major pieces of equipment such
as the lab exhaust fans, air-handling unit
supply fans and pumps have some level of
redundancy to allow maintenance to occur without having to shut down services
to the facility. The equipment rooms were
designed with appropriate space to allow
the proper maintenance of all equipment.
All equipment is monitored by the building management system for runtime
status to ensure proper maintenance can
be maintained. The static pressure drop
across all filters is monitored to ensure
proper service and replacement of filters
is maintained.
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Environmental Impact
The LSI was evaluated against Leadership in Energy and Environmental
Design ® (LEED) 1.0 criteria during
the design process to see how well the
university’s design guidelines for laboratories fit the goals of sustainability.
The university required that satisfaction
of any LEED criteria would need to be
accomplished within the project budget
and schedule. If pursued, LSI would
have come within a few points of certification, even though LEED 1.0 was not
designed for a complex research laboratory. This is a significant accomplishment for a laboratory building designed
to maximize the research space within
the facility. The following sustainable
design concepts were included as part
of this effort.
• A heat recovery system is part of
the design, signif icantly reducing
the amount of heat loss. This HVAC
system also meets laboratory safety
criteria of passing through the building
only once.
• Sustainable growth wood is used for
much of the project’s woodwork, including the extensive wainscoting in
virtually all of its public areas.
• The project is located within a rehabilitated “brown field” site, creating a
well-used complex on what was once
an underdeveloped impervious surface
parking area.
• The facility includes 20 major exhaust
fans on the roof, thereby not increasing
the perceptible noise to the 4,000 occupants of the residence halls located
within 500 ft (152 m).
Conclusions
The university and its stakeholders invested in the creation of LSI, the state-ofthe-art research facility, in consideration
of the emerging field of life sciences.
To entice potential scientists to join the
fledgling organization, the institute need-
ed to present an image of permanence
and longevity. In addition, the design of
the laboratory spaces was unique to other
campus facilities, making them more attractive to potential supporters.
In addition, the university is currently
tracking nine technologies that may lead
to patents and/or licensing agreements
with the pharmaceutical industry. The
technologies range from new research
techniques, to cell, gene and protein
interaction, to possible therapies. After
only two years in operation, the results
are impressive. Overall, the investment
of $96 million in the Life Sciences Institute is paying dividends for the students,
faculty and staff of the university, resulting in more jobs for the region and an
economic shot in the arm for the State
of Michigan. The university believes it
made a very cost effective forward moving decision with their research into the
life sciences and with its decision to build
this facility. Advertisement formerly in this space.
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