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4.16 Ventilation Rates

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4.16 Laboratory Ventilation Rates and Pressure Relationships

Laboratory ventilation is a critical engineering control that supports occupant safety, research integrity, and energy efficiency. Ventilation rates and airflow patterns are established based on the type of work performed, the hazards present, and room occupancy. These systems are designed to manage risk by providing adequate dilution, containment, and directional airflow.

Laboratory ventilation rates

Ventilation rates for laboratories are determined using a hazard-based approach. At Cornell, general laboratory spaces are typically designed using air change rates such as 6 air changes per hour occupied / 3 air changes per hour unoccupied (6/3) or 8 air changes per hour occupied / 4 air changes per hour unoccupied (8/4), depending on the nature of the work and the hazards involved.

Higher ventilation rates may be required for laboratories with increased chemical, biological, or physical hazards, while lower rates may be appropriate for low-hazard or write-up spaces. Ventilation rates are established during design and commissioning and are not adjustable by laboratory personnel.

Changes in research activities, materials, or processes may alter the hazard profile of a space and affect whether existing ventilation rates remain appropriate.

Pressure relationships and containment

In addition to air change rates, laboratories are designed with intentional pressure relationships to support containment. In general, research laboratories operate under negative air pressure relative to human circulation areas such as hallways and offices. This helps ensure that air flows into laboratories rather than out into adjacent public or administrative spaces.

Within laboratory suites, interior rooms such as tissue culture rooms, procedure rooms, or surgical spaces may be designed with different pressure relationships relative to the surrounding laboratory to support specific research or animal care needs. These rooms may be positive, neutral, or negative relative to the adjacent laboratory, while remaining part of an overall ventilation strategy that protects human circulation areas.

Changes in laboratory use

Because ventilation rates and pressure relationships are closely tied to how a space is used, changes in laboratory function—such as new research activities, new hazardous materials, procedural changes, or changes in occupancy—may affect whether existing ventilation remains appropriate. When the function of a laboratory space changes, notify EHS at askEHS@cornell.edu so ventilation conditions can be reviewed and verified for the updated use.

What laboratory personnel can do

  • Keep laboratory doors closed unless operational or safety needs require them to be open, to help maintain intended airflow and pressure relationships.
  • Be attentive to unusual conditions, such as persistent chemical odors outside a laboratory or unexpected airflow at doorways, which may indicate ventilation issues.
  • Temperature or comfort concerns should not be addressed by altering ventilation features (e.g., propping doors open). Report temperature concerns to building or facilities staff so they can be evaluated and corrected without compromising laboratory ventilation performance.
  • If ventilation concerns or odors are observed, contact your Building Coordinator so the issue can be evaluated and addressed.

Prompt reporting of ventilation concerns supports early identification of system issues and helps ensure research spaces continue to operate safely and as designed.

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