Ventilating offices automatically: window actuators for fanlights and night cooling

Updated: 08.11.2026

In brief: In the office, automatic window actuators provide fresh air without anyone having to reach the fanlights: during the day by CO₂ or schedule, in summer at night for cooling. In rain and wind the windows close by themselves. For individual rooms a 24 V ventilation control unit with switch is enough; for whole floors the actuators are connected to the building management system.

When is automation worthwhile in the office?

• Air quality: In meeting rooms the CO₂ level rises quickly; automatic purge ventilation keeps the air fresh, see CO₂ sensor.
• Summer: Night cooling lowers the room temperature in the morning, without an air conditioner.
• High fanlights: Windows that cannot be reached open at the push of a button instead of with a crank.
• Open-plan office: Cross ventilation through opposite windows exchanges the air faster.

Which actuators are suitable?

For fanlights and bottom-hung windows a Chain actuator again VS-KA with 250 N is usually enough. For heavy or wide sashes there are stronger force ratings and operation with two actuators. If many rooms are to be controlled centrally, the smart actuators of the i-series fit, such as the VS-KA-i with Modbusinterface.

Control: room or building

• Single room: Ventilation control 24 V with Ventilation switch, optionally with Rain sensor and Wind monitor.
• Whole floor: i-series actuators connected via Modbus to the building management system, which evaluates CO₂, temperature and weather.
• Night ventilation: only windows that cannot be reached from outside or whose opening width is limited; always close in rain and wind.

What planners should consider

• Protect closing edges on windows within reach, or only operate fanlights automatically.
• Manual operation must remain possible at all times.
• Size the power supply and cable for all actuators, see power supply calculator.
• Smoke exhaust is a separate topic and is planned project-specifically with an approved SHEV control panel.

Costs and examples for retrofitting can be found under Window actuator costs. For a quote, send photos and dimensions via the Project enquiry.

Read more: Cooling an office in summer without air conditioning: automatic night ventilation

Frequently asked questions

Can office windows be automated retrospectively?

Yes, usually without replacing the window: the actuator is mounted on the frame with a bracket. It requires space on the frame and suitable hardware.

Is night cooling worthwhile in the office?

Noticeably in well-insulated buildings with thermal mass: cool night air absorbs the heat from ceilings and walls. How much it brings depends on the building and location.

Do I need a separate control unit for each office?

No. Several actuators can run on one control unit; with many rooms, connection to the building management system via Modbus is clearer.