Break Out Session 3: Group A: Ventilation and Air Quality
-
Upload
juniper-octavio -
Category
Documents
-
view
20 -
download
3
description
Transcript of Break Out Session 3: Group A: Ventilation and Air Quality
Break Out Session 3:Group A: Ventilation and Air Quality
Chris Cosgrove, Cosgrove FDS, [email protected]
CCAC National WorkshopOttawa, ON – May 14, 2010 2
Purpose
• 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 WorkshopOttawa, ON – May 14, 2010 3
• 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
Know Your HVAC System…
CCAC National WorkshopOttawa, ON – May 14, 2010 4
Silencer
Electronic motor
Fan
Terminal unit
Humidifier
Room sensor
Temperature sensor
Humidity sensor
Pressure sensor
Filter
Cooling Coil
Heating Coil
Heat Recovery Coil (Cooling)
Heat Recovery Heating
Damper
Variable Frequency DriveConstant Volume DriveSilencerHeat Recovery coilSupply Fan
Return FanFiltration LevelHumidifierHeating CoilCooling Coil
Exhaust Exhaust
Outside Air Supply
HVAC Main System
CCAC National WorkshopOttawa, ON – May 14, 2010 5
Temperature sensor
Humidity sensor
Air Flow sensor
Heating Coil
Terminal unit
Humidifier
Ventilated Cage Racks Ventilated Cage Racks
Supply air
To Exhaust
Room HVAC Control
CCAC National WorkshopOttawa, ON – May 14, 2010 6
Redundancy
CCAC National WorkshopOttawa, ON – May 14, 2010 7
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 WorkshopOttawa, ON – May 14, 2010 8
Ventilation Rate Calculation• 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)V (cuft) *T(AC /h)
60
CFMhACcuft
CFMQ 196060
/20*5760)(
CCAC National WorkshopOttawa, ON – May 14, 2010 9
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 WorkshopOttawa, ON – May 14, 2010 10
Heat Load / BTU Output• ASHRAE
publishes Btu outputs
• Available for most species
• Based on weight & metabolic rate
CCAC National WorkshopOttawa, ON – May 14, 2010 11
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 - 40 40
Avg Btu / Hr - 136 136
Cages / Blower - 320 140
Blower Btu / Cage - 0.43 0.97
Blower Btu/ Hr per room - 425 486
Blower % Rm Btu - 10.1% 7.7%
CCAC National WorkshopOttawa, ON – May 14, 2010 12
Filtration
CCAC National WorkshopOttawa, ON – May 14, 2010 13
• 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
Pressurization
CCAC National WorkshopOttawa, ON – May 14, 2010 14
800 800
650650
150 150
400
950150
100Air Balance
CCAC National WorkshopOttawa, ON – May 14, 2010 15
If the room is positive pressure – measure supply CFM
If the room is negative pressure – measure exhaust CFM
Pressurization
CCAC National WorkshopOttawa, ON – May 14, 2010 16
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 WorkshopOttawa, ON – May 14, 2010 17
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 WorkshopOttawa, ON – May 14, 2010 18
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 WorkshopOttawa, ON – May 14, 2010 19
• 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.
ILAR Guidelines
CCAC National WorkshopOttawa, ON – May 14, 2010 20
• ….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.
ILAR Guidelines
CCAC National WorkshopOttawa, ON – May 14, 2010 21
Air Quality Considerations• Temperature (Heat Load)• Relative Humidity• Gases
– NH3– CO2
• Allergens– MUP
• Particulate• Chemicals
– Pheromones– Other Chemicals
CCAC National WorkshopOttawa, ON – May 14, 2010 22
Air Quality Considerations
• Air Quality for People• Air Quality for Animals• What should we monitor and why?
– Micro-environment– Macro-environment
CCAC National WorkshopOttawa, ON – May 14, 2010 23
Trends & Issues
• Animal Welfare• Research Impacts• Operating Costs• Energy Conservation• Environmental Health & Safety• Flexibility• Adaptability of Existing Facilities
CCAC National WorkshopOttawa, ON – May 14, 2010 24
Technology
• Ventilated Caging• Other Primary Containment Systems• Room Air Distribution (CFD Analysis)• Personnel Protective Equipment• Demand Based Ventilation
CCAC National WorkshopOttawa, ON – May 14, 2010 25
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 WorkshopOttawa, ON – May 14, 2010 26
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 WorkshopOttawa, ON – May 14, 2010 27
What Are Your Issues?
• Air Quality• Personnel protection• Research impacts• Facility Operations• Mechanical Design• Institutional Standards