The complex and sensitive nature of the design of vivarium facilities requires a thorough understanding of design standards, codes, and requirements that ensure animal welfare, research integrity, and staff safety. The nature of the research also fundamentally affects design choices, especially when it comes to infrastructure. The design approach to these facilities begins by asking a simple question:
What are you protecting? Is it the work you are doing? Or the people doing the work? The answer to this question begins to shape the layouts of your facility and the infrastructure needed to support it.
Suppose you're protecting the work you're doing, such as studying immuno-compromised species. In that case, the goal is to keep the research from being contaminated by sources such as human cells, dander, or other particulates. Even a small quantity of these contaminants can impact the research quality and yield false results. In this case, you want to design a Barrier Facility to keep out the contaminants. So, for example, our project for the Jackson Laboratories in Ellsworth, Maine, is designed as a barrier facility as JAX produces mice (including immunodeficient mice) that researchers worldwide use to study immunology, infectious disease, cancer, and stem cell biology.
On the other hand, when you are working with potentially infectious biological agents, the people doing the research have to be protected from the pathogens carried by the mice. Contamination can happen through physical contact or aerosols, so you need a Containment Facility to "contain" these agents. These facilities offer various methods of containment, often referred to as "primary" (protecting people and the immediate laboratory environment) or "secondary" (protecting the environment outside the laboratory).
What are the other differences between a containment and barrier facility? Both containment and barrier facilities require combinations of biosafety cabinets, animal enclosures, decontamination facilities, sinks, special ventilation systems, and airlocks, along with stringent operational procedures. However, one clear distinction between the two is how the air moves in one versus the other.
If you are focused on containment, you start with the smallest unit, the animal which is often brought to a biosafety cabinet. The air moves away from the researcher and into the biosafety cabinet through the building exhaust system, protecting the researcher. The room air is kept at a negative pressure relative to the spaces outside the lab. This approach is essential to protecting the researcher by making sure the air moves from the less hazardous area (the corridor outside the lab), into the lab, and then through the biosafety cabinet.
In a barrier facility, you are doing exactly the opposite of a containment facility. You are pushing air out. The biosafety cabinet is a positive air environment. It's moving air out, so the mouse or other research animals are not exposed to pathogens from the researcher or the surrounding spaces. This approach is essential to keeping the animals free of specific pathogens from humans or through aerosol transfer. So, in a barrier facility, the air from the room flows away from the biosafety cabinet, into the lab, and then to the corridors or airlocks outside the labs. This method requires the rooms to remain positively pressurized to the outside environment.
What if you want to do both? We get this question a lot. Clients are looking for greater flexibility because their research needs might change over time. To accomplish a shift from containment to barrier or vice versa, you must figure out how you can reverse the airflow (from negative for a containment facility to positive for a barrier) in an efficient and controlled manner. This shift requires an experienced mechanical engineer working closely with the users to understand how these changes impact the workflow and, therefore, the facility's layout. Our engineers can do this work, but it's costly to create this type of infrastructure for an entire facility in anticipation of a change in the future.
Instead of switching over an entire facility, we typically advise that you dedicate a single room or a series of rooms in a small portion of the program space for such flexibility. This approach limits the number of infrastructure upgrades required.
The growing complexity of research has heightened vivarium design requirements across the board. Containment versus a barrier facility is just one of the many choices that facility operators, users, architects, and engineers should work hand-in-hand on throughout the design process.