Lab Controls Glossary

Space and Environment

Term	Definition
Anteroom	Transitional space used to maintain contamination control and pressure relationships between areas.
Critical Environment	Space requiring controlled conditions for safety, containment, or process integrity.
Fume Hood	A ventilated laboratory enclosure that enables safe handling of hazardous materials while maintaining directional airflow to capture and exhaust contaminants at the source.
Offset Stability	Ability of a space to consistently maintain intended pressure relationships.
Pressure Cascade	Planned sequence of room pressures used to direct airflow between spaces.
Pressurization	The pressure relationship between two spaces, defined by the difference in supply and exhaust airflow that determines airflow direction between them.
Sash Management	Practice of controlling fume hood sash position to improve safety and reduce airflow demand.
Sash Position	Opening height of a fume hood sash that affects airflow requirements.
Temperature-Driven Overventilation	Excess airflow resulting from thermal loads rather than ventilation needs.
HVAC	Heating, Ventilation, and Air Conditioning systems used to control indoor environmental conditions.

Air Flow Terms

Term	Definition
ACH (Air Changes per Hour)	Number of times the air volume in a room is replaced in one hour; used to assess ventilation performance and safety requirements.
Airflow Offset	Difference between supply airflow and exhaust airflow used to maintain room pressurization.
Airflow Reset	Control strategy that adjusts airflow based on occupancy, demand, temperature, or risk conditions.
Exhaust Airflow	Air removed from a room to maintain ventilation and containment requirements.
Face Velocity	Air speed entering a fume hood opening, typically measured in feet per minute (fpm).
Fume Hood Diversity	Design assumption that not all fume hoods operate simultaneously at peak airflow.
Fume Hood Setback	Reduced airflow operating mode during inactivity or unoccupied periods.
General Exhaust (GEX)	Room exhaust airflow not associated with dedicated equipment such as fume hoods, snorkels, etc.
Supply Airflow	Conditioned air delivered into a space.
Tracking Control	Method used to maintain required relationships between supply and exhaust airflow.
Turndown Ratio	Ratio between maximum and minimum airflow capacity; indicates system flexibility.
VAV (Variable Air Volume)	Air distribution system that adjusts airflow according to demand.
CAV (Constant Air Volume)	Air distribution system that maintains a fixed airflow regardless of demand.
Ventilation Effectiveness	Measure of how efficiently airflow removes contaminants from a space.
Ventilation Setpoint	Target airflow rate expressed as an absolute value (e.g. cfm or a relative ACH) used by the control system.

Controls and Automation

Term	Definition
BAS (Building Automation System)	Centralized platform used to monitor and control HVAC, lab airflow systems, and building operations.
Control Sequence	Programmed operating logic defining system responses under varying conditions.
Differential Pressure	Pressure difference between adjacent spaces used to direct airflow.
Occupancy Control	Strategy that adjusts room operation based on occupancy status.
PID Loop	Proportional–Integral–Derivative control algorithm used to regulate airflow, pressure, or temperature.
Setpoint	Desired operating target for airflow, temperature, pressure, or other control variables.
Static Pressure	Air pressure within duct systems used to maintain airflow performance.
Temperature Override	Condition where airflow increases due to thermal demand instead of ventilation requirements.
Unoccupied Mode	Reduced operating mode used during periods of inactivity to lower energy consumption.
Performance Drift	Gradual degradation of system performance over time due to control, sensor, or operational changes.
Persistence	Ability of implemented improvements to maintain long-term performance and savings.

Fume Hood Terms

Term	Definition
Auxiliary Air Fume Hood	Fume hood designed to introduce supplemental air directly to the hood to reduce conditioned room air consumption.
Bypass Fume Hood	Hood design that allows additional air to enter through bypass openings as the sash closes to help maintain face velocity.
Combination Sash	Fume hood sash that can move vertically and horizontally for improved user protection and flexibility.
Containment	Ability of a fume hood to prevent hazardous contaminants from escaping into the occupied space.
Diversity	Design assumption that not all fume hoods operate simultaneously at peak airflow demand.
Face Velocity	Air speed entering the hood opening, typically measured in feet per minute (fpm), used as an indicator of containment performance.
Fume Hood	Ventilated enclosure used to capture and exhaust hazardous fumes, vapors, gases, or particulates generated during laboratory work.
Fume Hood Monitor	Device that displays operating status and alarms related to airflow, sash position, or face velocity.
Fume Hood Setback	Reduced airflow operating mode activated during inactivity or unoccupied periods to lower energy use.
Fume Hood Tracking	Control strategy that adjusts exhaust airflow based on sash movement to maintain target face velocity.
Hood Diversity Factor	Estimated percentage of hoods expected to operate simultaneously at design conditions.
Hood Exhaust	Dedicated exhaust airflow serving a fume hood system.
Hood Turndown	Ability of a fume hood to safely operate at reduced airflow conditions.
Low Flow Operation	Operating condition where airflow is intentionally reduced while maintaining containment requirements.
Occupied Mode	Hood operating condition during active use with standard airflow settings.
Sash	Movable transparent barrier at the front of a fume hood used for user protection and airflow control.
Sash Height	Vertical opening dimension of the sash that determines airflow demand.
Sash Management	Practice of maintaining proper sash position to improve safety and reduce energy consumption.
Sash Position Sensor	Device that measures sash location for airflow tracking and control.
Setback Mode	Reduced airflow mode during inactive periods while maintaining safe operation.
Slot Velocity	Air velocity through hood baffles or slots that influences airflow distribution and containment.
VAV Fume Hood	Variable Air Volume hood that adjusts exhaust airflow according to sash position or operating demand.
CAV Fume Hood	Constant Air Volume hood operating at fixed exhaust airflow regardless of sash position.
User Presence Sensor	Device used to detect occupancy near a hood and enable automatic setback strategies.
Work Opening	Usable opening area of a fume hood through which air enters the enclosure.
ASHRAE 110 Test	Standard performance test used to evaluate fume hood containment effectiveness.
Cross Draft	Air movement across the hood opening that can negatively affect containment performance.
Capture Efficiency	Effectiveness of the hood in collecting and exhausting contaminants generated inside the work area.
Wake Zone	Area of turbulent airflow around the user that can influence hood performance and containment.

Energy and Optimization

Term	Definition
Energy Intensity	Energy use normalized by floor area, activity, or process.
EUI (Energy Use Intensity)	Annual building energy use per unit floor area (typically kBtu/sf/year).
Energy Savings Potential	Estimated reduction achievable through optimization measures.
False Load	Unnecessary energy demand caused by control issues or excessive ventilation.
Optimization Opportunity	Identified action that can improve safety, performance, or efficiency.
Reheat Energy	Energy used to warm cooled supply air to maintain room temperature.
Retro-commissioning (RCx)	Process of evaluating and improving existing system performance through testing and optimization.
Simultaneous Heating and Cooling	Condition where heating and cooling occur together, increasing energy use.
Diversity Factor	Assumption that all loads or devices do not operate simultaneously at peak demand.