code requirements, design best practices,
and life safety reasons.
The number of times that the air is
turned over in vivarium spaces continues
to be an important topic when establishing
effective performance criteria. Although the
ILAR Guide has published guideline values,
AAALAC is open to creative approaches
that fulfill space performance requirements
while also reducing energy use, presuming
a well thought out and engineered solution
that performs well is in place.
Vivarium spaces are high energy users
primarily because they are served by
100% outside air. This differs from less
critical environments using recirculated air. As a result, heating and cooling
requirements for vivaria are significantly
higher. Therefore, establishing these criteria could be an iterative process to ensure
that performance is not sacrificed in
efforts to reduce energy use. Depending
on the application and space heating and
cooling loads, there may be significant
opportunities to reduce energy usage
without sacrificing performance.
• BAS indicated air flows will be verified
with a calibrated flow hood on both
supply and exhaust.
• Cage rack valve flows will be totaled
and verified to be accounted for in the
BAS exhaust flow. (Although these
valves may not be specifically measured
by the BAS, the total flow must be
accounted for to ensure that supply and
exhaust flows are accurate and correct).
• Room volumes will be verified against
BAS values to ensure calculated air
change rates are accurate.
• Calls for zone heating and cooling will
be tested and verified to operate and
Concurrent with establishing correct airflows for effective temperature control,
space pressurization—whether the space
is positive or negative relative to adjacent
spaces—is also established. This is also
called directional airflow because relative
space air pressure is what causes air to
flow from one space to another.
Input from the vivarium operations and
research staff is critical to establishing
effective air pressure controls. Typically,
vivarium operations and research will
establish either positive or negative pressure relative to adjacent spaces and clean
and dirty corridors. Specifying actual air
pressure values is not necessary. Design
engineers will interpret this information,
and based on room size, will establish a
design “offset” value between the supply
and exhaust air.
For example, in a space designed to be
under negative air pressure, air flows into
this space from adjacent spaces. Rooms
of this nature will be set up so that the
supply air is “offset” from the exhaust
air and to track it. Therefore, even under
constant volume conditions, if there are
any glitches in the exhaust system, the
supply will track it ensuring the space
remains negative. Similarly, positive spaces are set up to ensure the exhaust flow
remains at a programmed offset value
below the supply air flow.
It is not uncommon for the design
offset values to require adjustment to
account for field conditions. For example,
an engineer may specify an offset value
of 100 CFM. Upon testing, this value may
be adjusted slightly up or down to ensure
adequate differential air pressure.
• Room pressure will be verified relative
to adjacent spaces.
• BAS offset values will be reviewed and
verified to be consistent with actual
supply and exhaust offset values.
• BAS programming will be checked
to ensure the supply is tracking the
exhaust in negative rooms and exhaust
tracks supply in positive rooms.
• Local displays and Air Direction
Indicating (ADI) devices, such as the
ping pong ball in tubes will be checked
to ensure proper function. Dual direction indicators will be verified to go to
the middle under neutral pressure.
SPECIALTY SPACE CRITERIA
Cagewash areas represent a particular-
ly difficult challenge when it comes to
establishing pass/fail criteria and also
when maintaining safe and comfortable
environmental conditions for occupants.
Space relative humidity is difficult to
control because of the cycling of the
cleaning equipment, and allergen levels
tend to be high in these spaces because
of the activities performed. Maintaining
correct directional airflow from sterile, to clean to dirty spaces is critical
to space performance. These spaces
may require more iterative testing and
adjustment to achieve performance objectives.
Animal Holding Rooms
Animal holding rooms have higher ventilation requirements and cooling loads
because of increased population densities,
dander, and dust loads. Establishing supply and exhaust air flows for heating and
cooling, and air change rates that effectively maintain a healthy environment for
occupants and research, typically result
in higher values. Over time, these can be
refined downward incrementally to reduce
potential drafts, air noise, and energy use
without sacrificing performance.
Defining effective vivarium performance
criteria is critical to ensuring healthy and
safe work environments conducive to effective research. Engaging all stakeholders
and starting the process early maximizes
the effectiveness of these programs. The
AAALAC data referenced illustrates the
ongoing need for this definition and the
importance of regular performance verification. HVAC systems and the Building
Automation System computers and controllers that operate them require regular
maintenance and adjustment to changes
in building programs and space uses.
Effective vivarium management programs
that include defined performance criteria
and a regular verification plan will ensure
these environments remain current and
Doug Kumph is the Director of Operations
and a licensed professional engineer
at Cornerstone Commissioning, Inc. in