Infection Control

Solution Summary

The purpose of an airborne infection isolation room (AII) is to contain and minimise the risk of airborne infection transmission of respiratory viruses so that it does not spread to healthcare workers, other patients, and the community.

An AII room draws airflow in, keeps contaminates in, and exhausts to outdoors. Key room control parameters are Negative Airflow and Pressure Differential (Pa) which depends on:

  • Exhaust – supply flow differential (L/s). This must be monitored to verify room remains at negative airflow from cleaner corridor
  • Room envelope leakage area (cm²)


Volumetric Flow Tracking Control Strategy
This method measures both exhaust and supply airflow to directly control directional airflow and room pressure. Flow tracking can provide more stable control and is independent of room door operation.

Engineering parameters can be easily pre-set, and extremely tight room construction is not necessary for operation.

The negative air flow setpoint (L/s) as a minimum must be greater than the accuracy of the flow measurement and associated control error. We recommend at least 75 L/s (0.075 m3/sec) to ensure good reliable directional airflow.

Advantages of volumetric flow tracking include the following:

  • Low pressurisation level (normally -5 Pa)
  • Less tight construction required
  • Simple set of relative pressurisation levels (one or two levels)

Talk to An Expert

Improving the resilience of Australian hospital indoor environments will require practical and best practice engineering approaches.

If you are planning healthcare rooms, we would be very happy to discuss your project requirements.