In a modernized office building, a ctrlX AUTOMATION-based solution was implemented to maintain optimal indoor air quality by monitoring CO₂ levels and reacting with intelligent ventilation control. The goal: ensure employee well-being while minimizing energy consumption.
The ctrlX CORE continuously reads real-time data from multiple CO₂ sensors via the ctrlX I/O system. As soon as the concentration in a room exceeds a defined threshold, the control logic initiates the appropriate ventilation strategy.
If outside conditions are suitable, the system activates digital outputs to trigger motorized window actuators. Depending on the CO₂ level and current room conditions, windows are opened in stages. If the outside temperature is too low or windows are not sufficient, a mechanical ventilation unit is activated via Modbus TCP. This unit supplies preheated fresh air into the space.
Presence detectors are included in the logic to prevent unnecessary ventilation when rooms are unoccupied. This ensures fresh air when needed without wasting energy.
The application was implemented using CODESYS on the ctrlX CORE. For use cases requiring easier programming, the same logic could be built using Node-RED. The system is connected to the building management system via OPC UA, enabling monitoring, analytics, and centralized control. A custom visualization was created using ctrlX HMI.
Typical Use Cases:
Smart ventilation for meeting rooms or classrooms
CO₂-controlled fresh air supply in open-plan offices
Energy-efficient climate management in passive buildings
Key Features & Benefits
Direct control of window actuators and ventilation via digital outputs: The system responds to real-time CO₂ data by opening windows directly via digital outputs or activating a mechanical ventilation unit.
Programmable with CODESYS, optionally with Node-RED: The ventilation logic was implemented using structured PLC programming, but can also be easily built using graphical programming with Node-RED.
Integrated building automation using open protocols: Seamless integration via Modbus TCP and OPC UA enables data access and remote control through the building management system.
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This application is realized with the following components:
Contact
[icon name="dc_mail" color="black"] Sonja Koenig