General airflow through the laboratory space is a design element that safety is often asked to comment on. With the growing awareness of energy conservation for both sustainability efforts and costs savings, labs are being asked “how low can you go” when it comes to air changes per hour (ACH). The general heating, ventilation and cooling (HVAC) controls for the laboratory space can often be manipulated for efficient air supply that provides both occupant comfort and some degree of safety. When determining what the proper air flow should be, several factors must be considered in conjunction with ACH.
In offices, a percentage of the air supplied to the space can be recirculated from the same space, which saves on heating and cooling costs. All laboratory air is single pass, which means that it is 100% supplied fresh air from the outside. This is good news for lab occupants, as the air circulating in the space is all fresh, but not good news for facility managers that have to budget for the heating and cooling of all this air. Many labs are operating at legacy rates of 8-12 ACH. Some spaces are reducing airflow during non-work hours, such as nighttime or weekends to save money. Others are looking to reduce airflow in general. But what level is safe? The answer, as it often is in safety, is that it depends.
Although it contributes to the general safety of a laboratory space, the number of ACH required for a “safe” laboratory is not a defined number. The airflow is one piece of the puzzle and is not generally a major parameter relied on by safety professionals to protect workers in the laboratory. When determining the proper airflow for a laboratory space, it is important to evaluate the space as a whole. Items to consider include what work is being done, are there proper source point ventilation controls such as fume hoods available, and what is the direction of the airflow. All of these factors, and more, must be considered when determining the proper number of ACH for a laboratory space.
This is the sixth blog in a ten-part Industrial Hygiene series that we are featuring monthly. We welcome your input on the series! For additional information about laboratory airflow and determining the appropriate ACH for your laboratory, please email firstname.lastname@example.org.