Ventilating classrooms automatically: window actuators with CO₂ control

Updated: 07.11.2026

In brief: In a full classroom the CO₂ level quickly rises above 1,000 ppm. Automatic window actuators then open fanlights or bottom-hung windows until the air is good again, and close in rain, wind or cold. CO₂ is measured by a sensor on the building management system or on a ventilation control unit with sensor input; the actuators open the windows.

When should you ventilate?

As a guide value: up to 1,000 ppm the air is good, between 1,000 and 2,000 ppm you should ventilate, above that air quality is inadequate. More in the glossary under CO₂ sensor.

Which windows are suitable?

• Fanlights and bottom-hung windows out of reach: ideal for automatic ventilation, no risk of trapping for children.
• Windows within reach: only with protection at the closing edges or with operation where someone watches the movement.
• Cross ventilation: windows on opposite sides or towards the corridor exchange the air faster, see Cross ventilation.

Actuators and control

For fanlights and bottom-hung windows a chain actuator such as the VS-KA with 250 N is usually enough. If many rooms are to be controlled centrally, the smart actuators of the i-series fit, such as the VS-KA-i: they have a Modbus interface and can be connected to the building management system, which also evaluates the CO₂ values. For individual rooms, a 24 V ventilation control unit with switch and rain sensor is the simple solution.

What schools should consider

• Automatic with manual operation: teachers must be able to open and close at any time.
• Rain and wind protection: windows close automatically in bad weather and after lessons.
• Winter operation: short, intensive ventilation instead of permanent tilting saves heating energy.
• Smoke exhaust is a separate topic: SHEV is planned project-specifically and operated with an approved SHEV control panel.

Nursery and primary school

Stricter rules apply for small children: only fanlights and windows out of reach move automatically. Switches and control units are mounted so that children cannot operate them. Windows within reach remain manual or are protected at the closing edges . Typical planning mistakes are shown in the article 10 common mistakes when choosing window actuators.

Frequently asked questions

Can existing school windows be retrofitted?

In most cases yes, if there is space on the frame for actuator and bracket. Send us photos and dimensions via the Project enquiry.

Does Vent Systems also supply the CO₂ sensors?

We supply window actuators and ventilation controls. CO₂ measurement is usually done via the building management system or room sensors from the electrical planner; we coordinate the interface with you.

Tools: Calculate force and stroke with the Window actuator calculator, find the right model in a few questions with the actuator finder.

More guides: Ventilating offices automatically · Ventilating sports halls