Cosgrove

Report
Break Out Session 3:
Group A: Ventilation and Air Quality
Chris Cosgrove, Cosgrove FDS, Inc.
[email protected]
Purpose
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CCAC Subcommittee on air quality
HVAC Basics
Current guidelines (CCAC, Other)
Issues related to air quality
Current technology and impacts
What issues are you facing today?
What guidance is required?
CCAC National Workshop
Ottawa, ON – May 14, 2010
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Know Your HVAC System…
• Temperature, humidity
specific for species housed
• Reliability/Redundancy
• Maintenance Operations
• Energy conservation
• Failure modes to prevent
loss of life
• Filtration levels
• Pressure gradients
• Balancing
• Use of Airlocks
CCAC National Workshop
Ottawa, ON – May 14, 2010
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HVAC Main System
Exhaust
Exhaust
Supply
Outside Air
Silencer
Electronic motor
Filter
Cooling Coil
Heating Coil
Fan
Heat Recovery Coil (Cooling)
Terminal unit
Heat Recovery Heating
Humidifier
Room sensor
Temperature sensor
Humidity sensor
Pressure sensor
Damper
Variable Frequency Drive
Constant Volume Drive
Silencer
Heat Recovery coil
Supply Fan
Return Fan
Filtration Level
Humidifier
Heating Coil
Cooling Coil
CCAC National Workshop
Ottawa, ON – May 14, 2010
4
Room HVAC Control
To Exhaust
Supply air
Temperature sensor
Humidity sensor
Air Flow sensor
Heating Coil
Terminal unit
Humidifier
Ventilated Cage Racks
Ventilated Cage Racks
CCAC National Workshop
Ottawa, ON – May 14, 2010
5
Redundancy
CCAC National Workshop
Ottawa, ON – May 14, 2010
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HVAC Outdoor Design Criteria
• ASHRAE 1% Conditions(1% of the hours in the
year, outside air conditions will exceed design
criteria)
• Summer 90°F (32.2°C) at 50% RH – Worst
case scenario : 50% more energy in outside air
• Winter –16°F (-27°C) – Systems are
designed with –20°F (-29°C)
• Understand your conditions and what is
acceptable for research
CCAC National Workshop
Ottawa, ON – May 14, 2010
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Ventilation Rate Calculation
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H = 9 feet
W =16 feet
L = 40 feet
T = 20 AC/h
Volume V = 9 x 16 x 40
V= 5 760 cuft
Q (CFM ) 
Q ( CFM ) 

V (cuft ) * T ( AC / h )
60
5760 cuft * 20 AC / h
 1960 CFM
60
CCAC National Workshop
Ottawa, ON – May 14, 2010
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Heat Gain Calculations
• Thermal Gains Type
– Sensible (heat)
– Latent (humidity)
• Breathing out
• Perspiration
• Water Evaporation
• Sensible heat load is what is used to calculate
the heat load (Btu) of the space
CCAC National Workshop
Ottawa, ON – May 14, 2010
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Heat Load / BTU Output
• ASHRAE
publishes Btu
outputs
• Available for
most species
• Based on weight
& metabolic rate
CCAC National Workshop
Ottawa, ON – May 14, 2010
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Heat Loads & Higher Density
Std. MI
HD Mouse
HD Rat
Room Size / s.f.
400
400
400
Total Cages
400
1000
500
Animals / Cage
3
3
1.5
Animals / Room
1200
3000
750
Animal Btu / Hr per room
1509
3773
5803
Avg Blower Watts
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40
40
Avg Btu / Hr
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136
136
Cages / Blower
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320
140
Blower Btu / Cage
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0.43
0.97
Blower Btu/ Hr per room
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425
486
Blower % Rm Btu
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10.1%
7.7%
CCAC National Workshop
Ottawa, ON – May 14, 2010
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Filtration
CCAC National Workshop
Ottawa, ON – May 14, 2010
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Pressurization
• Pressurization Scheme is
mandatory for a good
vivarium design.
• Level of flexibility can have
an impact on the cost and
design
• Primary containment can
impact decisions
• Dependent on use and type
of primary containment
CCAC National Workshop
Ottawa, ON – May 14, 2010
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100
400
950
Air Balance
150
150 150
650
650
800
800
CCAC National Workshop
Ottawa, ON – May 14, 2010
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Pressurization
If the room is positive
pressure – measure
supply CFM
If the room is negative
pressure – measure
exhaust CFM
CCAC National Workshop
Ottawa, ON – May 14, 2010
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CCAC Guidelines
• In order to maintain potential air contaminants
below acceptable levels, it is recommended
that there be 15 to 20 air exchanges per hour
in a room.
• This recommendation, however, does not take
into consideration the efficiency of air
distribution, the number of animals held or
how they are being held.
CCAC National Workshop
Ottawa, ON – May 14, 2010
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CCAC Guidelines
• While this recommendation may be effective
for large numbers of animals housed in
conventional caging with less than ideal air
distribution (most systems), the requirement
may be considerably higher for animals
housed in static filter top cage units or less in
rooms where animals are housed in
ventilated cage units.
CCAC National Workshop
Ottawa, ON – May 14, 2010
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CCAC Guidelines
• The problems posed by the static isolator systems are now
being addressed by steady replacement with isolator systems
in which each cage is individually ventilated.
• Therefore, it is no longer useful to specify environmental
parameters, frequency of air changes, etc., without
specifying the type of equipment to be used for primary
containment. This may vary considerably between and among
species.
• The impact of the overall HVAC system must be evaluated at
the cage level.
CCAC National Workshop
Ottawa, ON – May 14, 2010
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ILAR Guidelines
• The guideline of 10-15 fresh-air changes per hour has been
used for secondary enclosures (the room) for many years and
is considered an acceptable general standard. Although it is
effective in many animal-housing settings, the guideline does
not take into account the range of possible heat loads; the
species, size, and number of animals involved; the type of
bedding or frequency of cage-changing; the room
dimensions; or the efficiency of air distribution from the
secondary to the primary enclosure (the cage).
• In some situations, the use of such a broad guideline might
pose a problem by over ventilating a secondary enclosure that
contains few animals and thereby wasting energy or by under
ventilating a secondary enclosure that contains many animals
and thereby allowing heat and odor accumulation.
CCAC National Workshop
Ottawa, ON – May 14, 2010
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ILAR Guidelines
• ….Even though that calculation [total-cooling-load
calculation method] can be used to determine
minimal ventilation needed to prevent heat buildup,
other factors such as odor control, allergen control,
particle generation, and control of metabolically
generated gases might necessitate ventilation
beyond the calculated minimum.
• When the calculated minimal required ventilation is
substantially less than 10 air changes per hour, lower
ventilation rates might be appropriate in the
secondary enclosure, provided that they do not
result in harmful or unacceptable concentrations of
toxic gases, odors, or particles in the primary
enclosure.
CCAC National Workshop
Ottawa, ON – May 14, 2010
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Air Quality Considerations
• Temperature (Heat Load)
• Relative Humidity
• Gases
– NH3
– CO2
• Allergens
– MUP
• Particulate
• Chemicals
– Pheromones
– Other Chemicals
CCAC National Workshop
Ottawa, ON – May 14, 2010
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Air Quality Considerations
• Air Quality for People
• Air Quality for Animals
• What should we monitor and why?
– Micro-environment
– Macro-environment
CCAC National Workshop
Ottawa, ON – May 14, 2010
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Trends & Issues
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Animal Welfare
Research Impacts
Operating Costs
Energy Conservation
Environmental Health & Safety
Flexibility
Adaptability of Existing Facilities
CCAC National Workshop
Ottawa, ON – May 14, 2010
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Technology
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Ventilated Caging
Other Primary Containment Systems
Room Air Distribution (CFD Analysis)
Personnel Protective Equipment
Demand Based Ventilation
CCAC National Workshop
Ottawa, ON – May 14, 2010
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Demand Based Control
• Study of vivarium room contaminants shows:
– Most vivarium areas are “clean” about 98+% of time
– Most vivarium areas have multiple “events” per week
• These events with elevated levels demand higher airflows
• Events can result from VOC’s/ammonia or particles
CCAC National Workshop
Ottawa, ON – May 14, 2010
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Demand Based Control
• Reduce 10 ACH minimum down to 8 ACH:
– Projected savings from extrapolating current data:
• Savings should increase to 51.3%
• Potentially reduce min further to 6 ACH:
– Savings likely depends on animal loading
• Reduce ACH min in support & procedure areas
– Apply DBC to bring min ACH to 4 ACH
• Implement VAV exhaust fan control strategy
– Sense exhaust air plenum for air cleanliness
– Reduce exhaust fan exit velocity when air is “clean”
– Potentially of cutting exhaust fan power in half
CCAC National Workshop
Ottawa, ON – May 14, 2010
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What Are Your Issues?
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Air Quality
Personnel protection
Research impacts
Facility Operations
Mechanical Design
Institutional Standards
CCAC National Workshop
Ottawa, ON – May 14, 2010
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