Why Redundancy Isn’t Always a Bad Thing

The primary focus of a vivarium is to create a simulated natural environment for raising animals for observation or research. Vivarium suites consist of several different types of areas: animal holding rooms, procedure rooms, quarantine space, storage areas, and specialized areas for cage washing, imaging, surgery, and necropsy. Each may have specific environmental and ventilation requirements, and these requirements may change as programs and protocols evolve. These facilities are designed with sophisticated control systems to create a safe, healthy, and comfortable environment for the animals, for the personnel, and to preserve the integrity of the research conducted therein. Many things can happen to building control systems; sensors drift, solenoids stick, inadvertent changes get made, and equipment fails which—without an independent monitoring system to verify the primary control system—could go undetected and adversely affect the animals, the personnel, and the research being conducted.

Of “Critical” research environments, vivaria offer some of the greatest challenges in maintaining a healthy and comfortable Indoor Environmental Quality (IEQ).

Heat loads can vary based on the species and population of animals and equipment in the spaces. The criteria for acceptable temperature and humidity control are more stringent than other research spaces to ensure the animals are kept in a suitable environment.

Should the output of a temperature or humidity sensor drift, the control system will see this as a change in the measured value and adjust its output to compensate. Not only will it be controlling to an incorrect reading, it will report this value as accurate. Signal drift tends to occur subtly and over time therefore climate conditions could be out of range and masked from detection for extended periods.

Odors and airborne contaminants are often present resulting in potential long-term health issues as well as unpleasant conditions. These odors and airborne contaminants may come in the form of Volatile Organic Compounds (VOCs). Particles such as dust and dander can carry pathogens and allergens throughout the space and can lead to health issues. Additionally, elevated levels of carbon dioxide, used for euthanasia, could lead to unintended results.

Without some form of comprehensive monitoring solution, if any of these parameters were to remain outside of acceptable limits, in any given room throughout the vivarium facility—would the appropriate personnel know? The most effective way to ensure these critical spaces are maintained at the desired levels 24/365 is to continuously monitor the parameters that influence the environment and notify the appropriate personnel should any parameter extend beyond its intended range (Figure 1).

Figure 1: Examples of TVOC and elevated particle count levels to provide EH&S professionals information about the location and severity of IEQ events within a buiilding.

In facilities where environmental conditions are known to influence the health and well being of animals and personnel, and redundancy of mechanical systems is the norm, would it not be prudent to have redundancy when monitoring the environmental parameters?

What are the Requirements?
The primary documents that guide the design and operation of vivaria include the Institute for Laboratory Animal Research (ILAR)’s Guide for the Care and Use of Laboratory Animals: Eighth Edition (the Guide); the Canadian Council on Animal Care (CCAC)’s 2003 guidelines on laboratory animal facilities—characteristics, design, and development; and the National Institute of Health’s (NIH) 2008 Design Requirements Manual (DRM).

All stress the importance of maintaining close control over temperature (+/-1°C) and to a somewhat lesser degree humidity (+/- 5-10%) as these may adversely impact the health and behavior of research animals (Figure 2).

Figure 2: These graphs display temperature and humidity readings for two animal holding rooms as scatter plots. The room on the top shows a broad scattering of readings with many outside the ILAR recommended range for mouse environments where the temperature and humidity readings for the room on the bottom are tightly clustered. These graphs may point to issues with the temperature and/or humidity control systems in the space on the left.

Ventilation systems must be designed to provide adequate ventilation to remove thermal loads generated by animals, personnel, and equipment; to remove odors, allergens, and airborne contaminants; as well as to create relative pressurization zones to prevent cross contamination between functional areas.

While the primary interest is in maintaining appropriate climate and IEQ levels in the microenvironment where the animals are housed, this can be influenced by the macro or room-level environment. How much depends on the type of caging and whether the supply and/or exhaust are ducted, drawn from, or exhausted to the room. Maintaining the macroenvironment at the proper climate, and keeping it free of any airborne contaminants will help ensure the quality of the microenvironment.

All of the guideline documents advocate that these spaces be continuously controlled and monitored at a daily or more frequent basis.

At a minimum, monitoring for temperature, humidity, light level, air change rate, and relative pressurization for each environmentally sensitive area should be a given. The question is, should monitoring extend beyond what the control system measures?

What Should be Monitored?
Temperature and moisture content in the air are interrelated and variations in the ventilation rate can greatly influence both. Because they relate to the comfort and behaviors of the animals, they must be controlled and monitored to ensure they are within an acceptable range.

Of equal or greater interest should be contaminant levels within the facilities that can influence the health and well-being of the animals and personnel working in these facilities.

Elevated VOC levels result in unpleasant odors and can lead to long-term health effects. Understanding the exposure levels, identifying the source, and notifying appropriate personnel in a timely manner, allows for corrective action to be taken. Monitoring the trend in TVOCs can also serve as a proxy for ammonia levels and provide an indication when bedding should be changed

Similarly, identifying increased levels of particles, particularly those in the respirable range which can transport pathogens and allergens, allow for corrective action to be taken.

Lastly, CO2 levels should be monitored even though ventilation rates in an open lab are generally sufficient; the presence of CO2 for euthanasia should be sufficient to warrant a measurement so as not to adversely impact the health of the animals.

Monitoring pollutant levels, notifying personnel, even overriding the ventilation rate to purge should be part of the room-level monitoring and control strategy to protect the animals and mitigate risk.

How Much is Enough?
The reasons to monitor are many; the questions come down to: How much? How often? What’s it going to cost—both to install and maintain?

The need to monitor the basic climate conditions; temperature, humidity, ventilation rates, and sometimes relative pressurization and light levels are well documented. The questions that need to be answered include: If there are other parameters that could influence the health and well-being of the animals or personnel likely to be present—shouldn’t those be monitored as well? If a system failure, a release, or spill occurs, how long is it acceptable that it goes undetected? In environments with redundant air handlers, fans and emergency power systems, where the expectation is 24/7 up-time, is it acceptable to rely on a single sensor for critical environmental measurements in each space? What is it worth to the organization to monitor pollutant levels to enable corrective action to be taken to avoid compromising a research program and providing a healthy and productive environment for personnel? What is the cost to the organization of having an IEQ issue and not knowing about it?

Odors and airborne contaminants are common in vivaria—they exist. A comprehensive IEQ monitoring solution can, in addition to monitoring temperature and humidity, also monitor VOCs, respirable airborne particles, and CO2 levels of individual spaces. This can provide valuable insight as to whether there are issues with fugitive emissions, protocols not being adhered to, filters, or the ventilation system itself that could adversely impact the IEQ. The question is how to do so in an efficient and cost-effective manner?

Manually monitoring and recording all the parameters that can impact acceptable IEQ levels would require a trained individual, or team of people, armed with an array of handheld instruments to go from room to room to make half a dozen measurements.

This results in a substantial investment in both equipment and resources and still may not provide adequate coverage.

A second option would be to install discrete sensors in each room for every parameter and bring these signals back to the building management system (BMS) or some independent monitoring system. There is a substantial cost to acquire the number of sensors of the appropriate types and install them in each space to be monitored. These sensors then need to be connected to some central monitoring system and programming would need to provide monitoring, trending, and event notification protocols.

There is sufficient research to suggest that sensors of this type require periodic calibration, on the order of once every six months to maintain their stated accuracy. Again, many of these sensors require specialized equipment, process, and skills that may not be practical in most facilities.

Yet another option is a sensing solution utilizing centrally located sensors with remotely installed sampling ports. This allows one sensor to measure air samples for multiple spaces thereby dramatically reducing the number of sensors required. A remote, centralized sensing approach means not only fewer sensors to install but that they can be located in an easily accessible location for ease of maintenance. This moves them out of the animal rooms so periodic maintenance does not disturb the animals or disrupt what is going on in those spaces.

Using one sensor to sense multiple locations provides the opportunity to perform true differential measurements where the room sample from the exhaust is compared to a reference sample from the supply. The benefits are twofold. A true differential measurement provides an accurate indication of climate or contaminant levels emanating from the room for source identification and if the sensor does drift, both the space measurement and the reference measurement will drift by the same amount, but the differential value will still accurately reflect the levels in the room

With a permanently installed solution, either integrated with the BMS, or with its own user interface, it is more likely to be able to provide more comprehensive, run-time data, historical trending, reporting, and the ability to alert users to climate or IEQ events. There are even opportunities to automatically override the ventilation rates of individual rooms to reduce the ventilation rate when climate and IEQ conditions are within recommended guidelines or increase the ventilation rate if pollutants levels reach a level that is unacceptable.

While research studies may run for between a few months and several years, the animal facility is expected to have a serviceable life of 20+ years operating 24/365. When building controls systems are designed, installed, balanced, and commissioned properly, you can be reasonably confident in having good control over the space and maintaining a stable environment. The challenge resides with what happens over time. Relying on as built commissioning and balancing reports and occasional “spot checking” of environmental conditions is not adequate. Monitoring the integrity of the environment on a continuous basis provides the greatest level of assurance that systems are functioning properly, procedures are being followed, and the environment is appropriate for the health and well-being of the animals, personnel, and research that occur within the facilities. Apply the carpenters adage “measure twice, cut once” to environmental monitoring—use redundant sensors whenever practical and true differential measurements to ensure the values you are looking at are meaningful. Utilize solutions that can analyze volumes of data and present it in visual and actionable ways. Apply solutions that provide performance and event reporting proactively and leverage emerging technology to stay on top of it. Measure beyond what the minimum recommendations or requirements are because the consequences of climate or environmental events can have a significant and long lasting impact on research programs.

Jim Fredericks is a Product Marketing Manager for Aircuity, Inc which is focused on providing intelligent airside efficiency solutions for commercial, industrial, and research facilities. Jim has over 27 years of experience in implementing and deploying controls solutions in the building controls and process control industries. Jim can be reached at