Churches and museums: opening high windows electrically with an inconspicuous actuator

Updated: 08.11.2026

In brief: In churches and museums, ventilation sashes are often located high up in historic windows. Electric actuators open them by switch or according to the indoor climate – important against damp and mould. The actuator should be as inconspicuous as possible, and as little as possible should be changed on the window.

What matters

• Inconspicuous: small chain actuators or a concealed installation, see concealed installation.
• Listed buildings: fixing with as little intervention in the historic fabric as possible; agree with the authority beforehand, see Listed buildings.
• Indoor climate: ventilate regularly when the outside air is drier than the indoor air – this is usually controlled by the building management system.
• High position: route cables neatly, plan actuator and bracket so they can be reached for later maintenance.

Which actuators are suitable?

For small ventilation sashes a slim Chain actuator again VS-KAis enough. If there is space in the frame, the VS-CKA 300 can be installed concealed. For steel and leaded glass windows we check in advance from photos where a bracket can hold securely.

steering

• Switch in the sacristy or plant room.
• VS-C24-7A ventilation control unit for up to 7 actuators, with Rain sensor.
• For humidity-based climate control: i-series actuators with Modbus on the building management system.

More on old windows: Box-type window in the glossary. For a quote, send photos and dimensions via the Project enquiry.

Frequently asked questions

May an actuator be mounted on listed windows?

The heritage authority decides case by case. Solutions that can be removed without damage and are hardly visible have good chances.

How do the cables get to the window?

Usually in a slim duct along the reveal or concealed in the frame. With wireless solutions the actuator still needs power at the window.

Does automatic ventilation help against damp in churches?

Yes, if controlled by humidity: ventilation only takes place when the outside air brings in less moisture than the indoor air contains. This is handled by a climate control or the building management system.