Cut Costs By Controlling Airflow
Biotech laboratory facilities consume up to 10 times more energy than commercial facilities. This is partly because lab buildings require 100% outside air at high volumetric flow rates for safety reasons that are mandated by regulations, codes, and standards. The National Institute of Health (NIH) states, "Laboratory buildings should be designed with ‘once-through' 100% outdoor air systems that automatically compensate for filter loading. Laboratory air shall not be recirculated."
To give you a visual perspective on the volume of air that a typical laboratory uses, I would like to compare it to something tangible such as the volume of a zeppelin like the Hindenburg, which was over 800-ft long and over 7 million cu ft in volume.
A laboratory with 100,000 sq ft of floor space, a 12-ft ceiling height, and 12-ach rate would fill the entire volume of two Hindenburgs in one hour. This constitutes over 14 million cu ft of 100% outside air in one hour that must be conditioned, supplied to the spaces, and immediately exhausted into the atmosphere. The cooling load would be almost 2,000 tons of refrigeration (based on a summer design day in Houston). Many factors drive the actual quantity of air introduced in the lab including:
- The amount of fume hood exhaust.
- The amount of air used to achieve pressurization control.
- The quantity of air required to satisfy the space cooling load.
- The ventilation rate required to remove the contaminants in a lab.
The first three items above will drive the airflow rate to the appropriate ach in order to satisfy these factors and cannot be reduced. The technology discussed herein is only intended to address the last item above.
Meeting standardsFacilities performing research with animals must follow the Animal Welfare Act CFR 9 parts 1, 2, and 3. Facilities that are funded by NIH must be follow The GuideFor the Care and Use of Laboratory Animals. This document is known as simply The Guide and is issued by the Institute of Laboratory Animal Research (ILAR).
The Association for Assessment and Accreditation of Laboratory Animal Care (AAALAC) uses The Guide for accreditation. The Guide indicates that recycled air, although it saves energy, is discouraged because many animal pathogens can become airborne or travel on formites and represents a great risk of cross contamination, particularly in the case of nonhuman primate and biohazard areas. The Guide recommends 10- to 15-ach airflow rate in vivariums. Several factors contribute to the high airflow rates in vivariums, including:
- The species and associated heat generation. Specific temperature ranges, based on the species, must be maintained. Rh must be between 30% and 70%.
- Particles such as dust, animal dander, and other formites.
- Toxic or odor causing gases such as ammonia.
- Toxic volatile organic compounds (VOC).
For lab spaces, ASHRAE, OSHA, and prudent practice state that 4 to 12 ach is normally adequate if primary containment such as fume hoods is used. Four ach is the minimum recommended unoccupied air change in a lab per NFPA 45 and OSHA standards. Table 1 summarizes criteria and source.
Using it when you need itThe cost of fossil fuels continues to rise and consequently, so does the cost of electricity. This drives up the operating cost of laboratories and vivariums. Many would argue that it would be far more beneficial to use money on research and development as opposed to the operating costs of facilities. For example, volumetric airflow rate is measured in ach, and the majority of the time the ach requirement in a lab can be half as much or even less, unless a safety event occurs that requires dilution of that air. So why pay for twice the energy when you don't need to?
Similar concepts have been successfully implemented in parking garages measuring CO, and in buildings such as offices, courthouses, and schools that measure CO2 concentrations. Refrigeration machine rooms are another application that is required, by mechanical codes, to be monitored. Laboratories have much more dangerous chemicals and gases than do refrigeration machine rooms so why aren't labs monitored? Facilities managers can reduce ach by monitoring the air in the laboratory and provide higher ach only when needed, such as during a chemical spill, high heat loads, high fume hood demand, or high animal occupancy in a vivarium.
Normally, a lab can operate at low ach with some adjustments to thermal requirements and changes in hood sash heights. In the event that a spill occurs, such as someone dropping a hazardous chemical in the lab, a sensor would pick it up and immediately switch to 12 to 20 ach or more to increase the air dilution until the emergency event is under control. Once the air is back to a safe level, the system can be reset back down to the low normal operating ach.
This would inherently make the lab safer because one can exponentially increase the ach to a much higher rate to dilute the air. Hypothetically speaking, if a lab is traditionally set to 10 to 12 ach for proper air dilution, and with this new system one can go from 6 to 60 ach, you can obviously dilute the air much quicker and more effectively.
The higher ach would only be introduced during an emergency condition and thermal and humidity control would not be a priority; meaning, the equipment controlling temperature and humidity only needs to be sized for normally low ach conditions and not be oversized.
The case for demand ventilationMonitoring air for CO2 in schools, office buildings, courthouses, etc., and used to control the HVAC system is known as demand ventilation. Why is demand ventilation not used in laboratories where toxic and flammable chemicals are used?
This technology utilizes a central suite of sensors integrated into a BMS for monitoring and control of up to 30 zones. The sensors can be selected for the specific known gases that will be used in the lab or can be selected for a wide variety of gases and toxins and switched out at a later time if certain known gases will be utilized. One can also monitor labs using individual dedicated sensors for each lab; however, this will drive up the cost. Dedicated sensors may be warranted for high hazard or special labs.
There is no way of detecting every possible substance or compound; however, in laboratories the use of a photo-ionization detector (a type of total volatile organic compound [TVOC] sensor) can accurately detect hundreds of commonly used laboratory chemicals. This sensor, coupled with a laser-based particle sensor to identify aerosol vapors and smoke along with specialty gas sensors (for acids and other toxic gases), will encompass the majority of airborne chemicals of concern.
Oxygen depletion that may cause suffocation can also be monitored. Labs or bottle storage closets and areas that contain large amounts of gases that can displace oxygen if they leak or purge can also be monitored. Conversely, oxygen enrichment environments that may create explosive conditions can also be addressed.
The technology is derived from the same concept as demand ventilation in office buildings, schools, and courthouses, but looks at much more than CO2:
- Air cleanliness
- TVOC: PID
- Air acidity (pH)
- Particles: laser-based particle counter
- Comfort and ventilation
- Humidity: dewpoint hygrometer
- Potential sensors
- Differential static pressure
- Chemical and biological agents
Largest group detected are organics (contain carbon):
- Aromatics: Have a benzene ring: benzene, toluene, xylene
- Ketones and aldehydes: Have C=O bond: acetone, MEK.
- Amines and Amides: Also contain nitrogen: diethylamide
- Chlorinated hydrocarbons: trichloroethylene (TCE), PERC
- Sulfur compounds: mercaptans, sulfides
- Unsaturated hydrocarbons: butadiene, isobutylene
- Alcohols: Isopropanol (IPA), ethanol
- Saturated hydrocarbons: butane, octane
Some inorganics can also be detected:
- Ammonia, hydrogen sulfide (H2S), nitric oxide
- Semiconductor gases: arsine, phosphine, ...
- Bromine and iodine
- Air (N2, O, CO2, H2O)
- CO2 and water (dewpoint) are detected separately
- Common toxins (CO, HCN, SO2)
- CO is detected separately
- Other toxins if a concern, can be detected separately
- Acid gases (HCL, HF, HNO3)
- Separate acid gas or PH sensor can detect many acids
- Others: Freon, ozone, hydrogen peroxide
- Usually less of an issue, but can be detected separately
- Non-volatiles: PCBs, greases
- Not an issue since rarely airborne
- If released as an aerosol, can be detected by particle counter
- Oxygen depletion and/or enrichment environments
Why dilute clean air with clean air? A case study indicated that 0.07% of the time the air in labs remained clean, yet the maximum airflow was introduced in the space 24/7/ 365. Why not provide the high number of ach only when you really need it?
Harvard University is conducting performance testing on the technology to validate the air monitoring system and to better understand airflow rates that laboratories actually need.
Typically a lab requires 8 to 12 ach (not including spaces containing laboratory animals which may be as high as 15 ach) but may only need to operate at 4 to 6 ach. The NIH requires 15 ach for animals and the CDC ( Guidelines for Environmental Infection Control in Health-Care Facilities) requires 12 ach for airborne infection isolation and for protective environment.
Saving energy by using technologyA key way of conserving energy and saving labs money is minimizing ach through the EMS by continuously sampling the air and providing the proper amount of ach to satisfy environmental conditions. This would allow a lab to constantly run a lower number of ach. If someone in the lab dropped hazardous chemical, a sensor would pick that up and immediately switch to 12 to 20 ach or more to increase the air dilution until the emergency event is under control.
Table 2 illustrates spill dilution concentration vs. time for various ach, and shows how a dynamic system that responds to a spill would provide a much safer atmosphere in a shorter period of time than a system that only provided a 6-ach baseline.
Incidences do happen, particularly when you have rookies such as students or interns working in the lab environment who are not fully aware of the safety protocols. Even the pros mess up on occasion. I worked for a university where a principal researcher (PR) worked and he continually violated protocols by leaving quarts of spilled ether on floors, countertops, and all over the lab. The PR even stored a mountain of 1-gal cans of ether without the covers on them in non-lab areas such as offices that had return air systems. The ether would make its way to the offices and conference rooms of the executive board and after they fell asleep in their offices a couple of times, the PR was fired.
In another recent incident in the news, at a predominant university in Boston, a senior scientist performed experiments on the lab bench and not in the fume hood where protocol required him to do so. As a result, he and two of his colleagues contracted an accidental infection with a dangerous bacterium they were studying called tularemia.
Incidences such as these rarely occur, however; as long as there is human involvement there will be human error. On rare occasions, I have seen scientists who not only violated safety protocol, but also have taken upon themselves to alter the HVAC (system without an engineering analysis), causing a change in the pressurization in the laboratory.
In one case, the scientist changed the damper settings for the supply and exhaust and cut into the ductwork to hook up a piece of laboratory equipment that he had purchased.
Indoor environmental quality monitoring and sensorsIndoor environmental quality (IEQ) monitoring increases lab/vivarium safety in the following ways:
- Validates safe operation of a lab/vivarium
- Detects improper bench use of chemicals
- Rapidly senses spills, fires, and rogue reactions
- Detects improper procedures/bedding changes
- Checks space pressurization, temperature and rh accurately
- Documents good IEQ and protects animals
- Continuous monitors of many IEQ parameters
- Rapidly detects significant changes in room IEQ
- Increases offset during spills automatically
- Increases ach to max dilution when needed
- Reduces room noise levels at lower ach
- Allows for safer lab airflow control
- Increases hood capture from reduced drafts
- Maximum dilution (12 to 15 ach) for spills, leaks, etc.
Refer to additional information on gas detection and technologies in the Gas Detection Handbook by MSA Instrument Division (www.msagasdetection.com).
In order to remain flexible, the sensors should be easily replaced with a gas sensor that will match the specific gases that may be used in the lab. The air monitoring system should be able to change as the research and science changes by being a "plug and play" system.
Air monitoring and LEED®Air monitoring technology provides an opportunity for LEED® points under the USGBC. Several points are possible with this new technology, including:
- IEQ potential: 3 points.
- EQ 1: Permanent CO2/ outdoor air monitoring
- EQ 3.2: Construction IAQ management plan
- EQ 7.2: Permanent comfort monitoring
- Innovation in design potential: 2 points.
- IEQ monitoring point:
- Exceeds EQ 1 CO2 monitoring
- Continuous commissioning point:
- Exceeds EA 3 Additional commissioning
- Energy and Atmosphere potential: 6 points.
- EA 1: Optimize energy: up to ~ 4 points.
- EA 3: Additional commissioning: 1 point.
- EA 5: Measurement and verification: 1 point.
- IEQ potential: 1 point
- EQ - 3.1: Construction IAQ management plan: 1 point.
Because this idea is relatively new, some have hesitated to learn more about it. But we should be mindful of emerging technology. In this case, such a system would be useful for several reasons: safety, energy conservation, and liability. While safety should always be a lab's number one priority, lab managers, engineers, and owners should also be interested in the legal aspects of the system. The system, which would monitor spikes in environmental conditions such as chemical hazards, would document that the lab meets safety thresholds at any given time. The owner could then have historical documentation that can be used to demonstrate that safe environmental levels were maintained. Furthermore, if there was an incident then the times, durations, location, and actions taken could be recorded.
Actual installations and applicationsIn the last five to 10 years or so, a concept called demand control ventilation (DCV) was introduced into HVAC controls systems. DCV is a new concept in laboratories that was introduced within the last year and is in its infancy stage.
According to Aircuity, a manufacturer of this technology, there are only two known laboratory installations of their OptiNet ™ Multiplexed Lab Facility Monitoring and Control Systems. One has been installed at Harvard University in Cambridge, MA, and one is in Lawrence Livermore National Labs in Berkley, CA. Two of these OptiNet ™ Lab monitoring systems are proposed in Houston.
I designed a laboratory air monitoring system for a client in Cambridge, MA, using sensors manufactured by MSA Instruments. The total square footage of my client's labs was 220,000, with 58 different types of labs for 24 different user groups. The sensors were located within the individual labs. These labs were designed with VAV and the sensors were selected for specific gases and chemicals that were going to be used in those labs.
The system was continuously monitored system with audible and visual alarms that were tied into the BAS. Chemicals and gases were measured down to the parts per billion (ppb). The system has three levels of status (alarm modes), with corresponding visual light beacons. These alarm modes are as follows:
- Green light indicates normal system status.
- Amber light indicates trouble with the system or that a gas or chemical was detected and reached a low level range measured to a specific ppb, and an alarm would be sent to the BAS. This mode lets everyone know that a low level detection exists. The BAS had the capability to automatically page the principal researcher, and other key personnel to notify them of the problem.
- A red light indicates that the chemical and gas detected in the amber alarm mode continued to rise and reached a specific defined level in ppb. An alarm signal would be sent to the BAS. In addition to the red light beacon, an audible evacuation siren would be enabled and the ventilation supply and exhaust system would go into an emergency purge mode. Depending on the hazard, the emergency purge mode would go from 8 ach to 30 or 40 ach.
Many gases were used in these labs that could displace oxygen if inadvertently released; therefore, oxygen depletion was monitored. Some labs could potentially have explosive atmospheres, consequently; the explosive levels of gases and chemicals were monitored (LEL), as well as oxygen enrichment levels.
One specialty lab utilized hydrogen sulfide and a specific sensor was used that could measure hydrogen sulfide down to 2 ppb. In addition to monitoring the system, a lab occupant has the option of pressing a red palm button upon evacuation of the premises if an incident occurred and place the system into the red alarm mode.
ConclusionThis technology is based on providing a minimum quantity of air to save energy, providing additional air (on rare occasions) during an incident for safety purposes, and providing a means of documenting the IAQ of the lab or vivarium to ensure that it has been maintained at a safe level.
Just imagine the energy saved by eliminating the energy required to condition the volume of one of the two Hindenburg zeppelins per hour. An owner must ask himself, "Can I afford not to provide a dynamic air monitoring system for energy, safety, and logistical purposes?"
EDITOR'S NOTE: This is an extended version of the article that appeared in the print version of ES.