break out session 3: group a: ventilation and air quality chris cosgrove, cosgrove fds, inc....

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?


• 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…


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


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


Redundancy


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


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)(


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


Heat Load / BTU Output• ASHRAE

publishes Btu outputs

• Available for most species

• Based on weight & metabolic rate


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%


Filtration


• 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


800 800

650650

150 150

400

950150

100Air Balance


If the room is positive pressure – measure supply CFM

If the room is negative pressure – measure exhaust CFM

Pressurization


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 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 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.


• 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


• ….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


Air Quality Considerations• Temperature (Heat Load)• Relative Humidity• Gases

– NH3– CO2

• Allergens– MUP

• Particulate• Chemicals

– Pheromones– Other Chemicals


Air Quality Considerations

• Air Quality for People• Air Quality for Animals• What should we monitor and why?

– Micro-environment– Macro-environment


Trends & Issues

• Animal Welfare• Research Impacts• Operating Costs• Energy Conservation• Environmental Health & Safety• Flexibility• Adaptability of Existing Facilities


Technology

• Ventilated Caging• Other Primary Containment Systems• Room Air Distribution (CFD Analysis)• Personnel Protective Equipment• Demand Based Ventilation


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


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


What Are Your Issues?

• Air Quality• Personnel protection• Research impacts• Facility Operations• Mechanical Design• Institutional Standards

break out session 3: group a: ventilation and air quality chris cosgrove, cosgrove fds, inc....

Documents

ccac national workshop

filtration slide

space slide

research slide

redundancy slide

cuft slide

hvac system slide

room hvac control slide