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Energy Efficient VivariumsPeter Rumsey, P.E., Rumsey Engineers, IncGlen Berry, NCARB, Design for Science
Why Vivariums?
Rapid Growth in Vivarium Construction and Use
High Energy Intensity – Typically 1.5 to 2.5 more energy intensive than traditional labs
High Steam UsageHigh Air Change Rates
Criterion #1: Guide for the Care and Use of Laboratory Animals
Excellent reference manual for planning and design of vivarium facilities.
The Guide was written in 1996.
Page 32: “The guideline of 10-15 air changes per hourhas been used for secondary enclosures for many years and is considered an acceptable general standard.”
The Guide does not mention ventilated cage racks, as they did not exist as a tried/tested/proven product for animal holding in 1996.
Criterion #2: NIH Design Guidelines
Another excellent reference manual for the planning and design of vivarium facilities.
Published in 2003
Does acknowledge ventilated cage racks as an acceptable form of housing rodents.
Page F.70: “The air-handling system design should comply with the requirements described in the Guide for the Care and Use of Laboratory Animals.”
Page F.71: “If microenvironments are employed for animal holding, the minimum ventilation requirement may be reduced to 10 air changes per hour plus the sum of the microenvironment airflow.”
Concept #1: Understand the difference between primary and secondary barriers.
science laboratories: The chemical fume hood is the primary barrier, and is the primary method of capture and containment of volatile chemical fumes.
BSL3/4 labs: The biological safety cabinet is the primary barrier, and is the primary method of capture and containment of airborne pathogens.
vivaria: the ventilated cage rack is the primary barrier of rodents, and is the primary method of controlling air change rate, temperature, and humidity of the housing environment.
In all of the above, the room is the secondary barrier, and should always be thought of as such. The room cannot and should not provide the same level of capture/containment as the primary barrier.
Building Basics
Location – 30 miles south of San Francisco on coast
Size – 115,000 sf – 15,000 s.f. vivarium on ground floor (~50 double sided 144 count cage racks)
Purpose - Biomedical Research
Cost – approximately $610/sf
Minimum LEED Silver and 30% energy savings
Vivarium Floor Layout
Holding Rooms
Cage Wash Area
Mechanical LoadingDock
Vivarium~15K sfBasement Floor
Concept #2: The secondary barrier (the room) envelope does not need to provide the same level of capture and containment as the primary barrier.
Then (Lab planning and design): 10-12 air changes per hour
Now: 6 air changes or 1 cfm/sf with even lower rate for unoccupied mode.
Then (vivarium planning and design): 10-15 air changes per hour
Now: still 10-15. Has not addressed the role of the ventilated cage rack as the primary barrier.
Perhaps we can allow the equipment to solve the energy consumption problem, by reducing the effective envelope for which the air change rate is required. Similar to the function of a chemical fume hood or biological safety cabinet……
HVAC Systems
Dedicated AHU – 40,000 CFMTwo fans one for redundancy
Chilled Water SystemOne 300 ton – peak use full buildingOne 100 ton – peak use vivarium only
Generator - 600 kWBack-up for all Vivarium uses except steam AHU, Lights, Chiller, Pumps,
Air Change Rates
Typical Open Cage Rack Holding Rooms15 to 20 Air Changes per hour (approx. 3-4 cfm/sf)
Ventilated Cage Rack Holding Rooms10 air changes per hour (approx. 2 cfm/sf)
Vivarium Options Considered In Schematic Design
Option 1 - All Open Cage Racks in Holding RoomsAHU: 49,000 cfmAHU and Chiller Costs: $613k
Option 2 – 50% Open Cage Racks/50% Ventilated Cage Racks
AHU: 40,000 cfmAHU and Chiller Costs: $482k
Option 3 – 100% Ventilated Cage RacksAHU: 36,000 cfmAHU and Chiller Costs: $442k
Vivarium Options Costs
OptionVivarium HVAC
Costs
All Open Cage Racks $819,000
50% Open / 50% Ventilated $723,000
All Ventilated Cage Racks $663,000
Selected Option
CFD Analysis
Purpose Determine Optimal Placement of Supply and Return Diffusers in Open Cage Rack Rooms
Steam Load Summary
EquipmentRegular Steam
Clean Steam Comments
Peak Ave Peak AveTunnel Washer 2400 - - - 1000 lbs/hr dryerCage & Rack Washer 600 - - -
Medium Sterilizer(26 x 37.5 x 60") - - 335 185
Can find alt. equip 10% lower steam, such as Getinge 700LS
LSR Sterilizer - - 800 450
Autoclave - 1st floor - - 60 5610% additional savings possible
Autoclave - 2nd floor - - 60 5610% additional savings possible
Medium Autoclave - 3rd floor - - 335 185
Can find alt. equip 10% lower steam, such as Getinge 700LS
Autoclave - 4th floor - - 60 5610% additional savings possible
Autoclave - - 60 5610% additional savings possible
Autoclave - - 60 5610% additional savings possible
Glasswasher (future) - - 300 -
TOTAL 3000 - 2,070 1090
60% OF STEAM DEMAND IS IN THE WASHERS
Tunnel Washer
Manufacturer High Pressure Steam Use (lbs/hr)
SteamRequirements if supplemented with 140 deg F Hot Water
Can use low pressure steam
Getinge 1200 600 - 950 No
IWT Technoplast 661 Not recommended No
LYNX 1400 Not recommended Yes
Steris 1300 Not recommended Yes
Cage and Rack Washer
Manufacturer High Pressure Steam Use (lbs/hr)
HP SteamRequirements if supplemented with 140 deg F Hot Water
Can use low pressure steam
Getinge 800 400 Yes
IWT Technoplast 600 Not recommended No
LYNX 1200 600 Yes
Steris 1400 Not recommended No
Other Strategies for Lower Energy Use in Vivariums
Improved venting strategies for ventilated cage rack systemsImproved fans on ventilated cage racksUnoccupied or lower occupancy turn downAutoclaves improvementsLow energy lightingDemand Controlled ventilation
Others??
Conclusion (food for thought)
Let the primary barrier (fume hood, BSC, ventilated cage rack) define the envelope for air change rate and environmental controls. Reduce the secondarybarrier (the room) air change rate to lower levels that save energy and still provide a safe working environment.
Animal Holding Rooms:Use Ventilated Cage Racks Room - 6+ air changes per hour occupiedRoom - 4+ air changes per hour unoccupied