Arens International shares its expertise in automated windows and natural ventilation systems to help designers develop accurate specifications for their projects.

There are several important considerations to be taken into account during the design phase of the project. These include window actuators, window sizes, fastenings, window openings and locations, stays and hinges, mechanical and electrical specifications, and cabling.

Window actuators

Arens recommends its chain and linear actuators to enable manual operation of high level windows and louvres for natural ventilation; provide a fully automated natural ventilation system; and facilitate natural and smoke ventilation systems.

Window sizes

Awning sashes should ideally be at least 500mm high to avoid the need for chains to be shortened. Windows should also be 450mm wide or greater to ensure there is adequate space for the actuator to be mounted. Custom solutions are available from Arens for smaller windows, but early consultation will be required. For designs incorporating wide sashes, it is recommended that any window greater than 1200mm should have two points of attachment to avoid bending or twisting of the frame.


High wind loads can cause some fastenings to detach from timber and aluminium sections. This is an important consideration in coastal and exposed locations as well as multi-level buildings. If the project incorporates any form of displacement air conditioning, it can lead to increased pressure on the windows and attachments. Appropriate fastenings must be selected after due consideration of these factors.

Window openings and locations

Operable windows at high levels reduce a number of risks that may exist with lower level windows, including lower risk of entrapment as they are out of reach; reduced security issues and minimised risk of intrusion from night purging; and avoidance of draughts, particularly in the cooler months.

Stays and hinges

The capabilities of the hinges must match the desired degree of opening. For example, if top hung hook hinges are being used, the chain in the actuator will need to be restricted. When stays are selected for awning sashes, their travel must match or exceed the chain stroke of the selected actuator. Key considerations also include use of non-friction stays or hinges and avoiding stays with rubbing blocks.

Co-ordination with mechanical and electrical specifications

When choosing electric actuators for windows, it is essential to coordinate with mechanical and electrical specifications such as how they are to be switched and powered, where the windows are located, the number and location of GPOs, and how the cabling is to be brought through the window sill.


The cable dimensions required will be determined by both the number of actuators and the length of the run.