Simple or smart—the ins and outs of natural ventilation

24 August 2021

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Actuated or motor-driven window openers are popular in modern, healthy Green Star buildings because they help save on the cost of mechanical ventilation and make for a more healthy indoor environment. But knowing which one to choose comes down to various factors.

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Different situations demand varying levels of complexity. Specifiers need to be aware of the considerations right at the design phase, says Peter Millard of EllisCo, which has played a major role in some of New Zealand’s largest and most ground-breaking architectural/industrial projects.

“You need to know when to select a simple push button controlled actuator or a smart programmable actuator linked to building management systems and tied in with heating and cooling systems.”

He explains: a window actuator is a component that facilitates the opening of a window via motor-driven automation. In short, it is an electric window opener and can come in many forms including: chain, rod, folding arm, or rack and pinion mechanism.

Peter says his main supplier, Danish company Windowmaster, has developed world leading window actuators and natural ventilation control system solutions to improve the indoor climate in buildings, to benefit people’s health, productivity and the environment.

EllisCo installed WindowMaster Smart PLUS controllers with BACNET Ethernet IP in the Beatrice Tinsley building at the University of Canterbury.

They give the following five pointers on what to consider when selecting an actuator.

● Do you need a simple or smart actuator?

Simple actuators controlled by push buttons are good for residential or school classrooms where there are 10 to 12 opening windows that students and teachers can operate to control their environment.

But if you have a smart actuator you can programme how the windows open including the force and speed when opening and closing. The slower they are, the less noise they make. In an office building environment, it is not unheard of to have up to 50 windows on any given side. If they all operate at once they can be quite loud and annoying.

That’s one of the key benefits of a smart actuator. They let you control the speed to reduce noise.

● Do you require a device that adds extra safety for high-risk locations or obstacles?

Because actuators are electric opening and closing devices, if you put your hand in the open window slot, they can be dangerous. Smart versions have inbuilt obstacle detection. If an obstacle prevents operation, the actuator detects it and will reverse to avert any damage. Simple devices are safe if they’re used on windows positioned higher than 2.5metres from the ground. If not, you should select a smart actuator or add other safety functions into the design.

Sometimes an architectural design has windows located at floor level so the air can enter at a low level—for example in university atriums—so safety precautions are necessary.

● Do you need to conceal wiring routes for actuators?

Actuators are an electrical device so they need a power supply through cables. You need to think about how to run the cable in a tidy, aesthetic fashion. Make sure that’s not forgotten when you’re specifying smart actuators.

There are two ways you can do it. Sometimes you can run the cables through the aluminium joinery. That needs to be completed early in the design with the aid of the joinery or façade manufacturer.

Alternatively, a matching cover profile in a powder coated aluminium box section might be an option. Again, this is often overlooked during the specification and tender process but a little thought during specification can reduce cost and improve aesthetics later.

Most joinery or façade manufactures will have channels or box sections they use for this purpose.

● What will the actuators be used for?

There are three types:

The simple actuators controlled with push buttons for classrooms or residential use.
Smarter actuators connected to building management systems come into play for larger schools, universities and commercial projects
Smart actuators that are part of a smoke extract system for use in atriums, stairwells for example. Actuators and their controls will be designed and tested to work as part of a safety system. Each of these would be tested to a certain standard to make sure it operates in an emergency.

● What size and type of opening actuators do you need?

The most common type of window in New Zealand is a top-hinged window, which opens at the bottom. However, bottom-hinged windows that open from the top and which are popular in Europe, are becoming more common. Then there are skylights. If you’re pushing them up from the roof, the actuator has to be able to take more weight. Similarly, louvres are also becoming more common in commercial buildings and require a different approach again.

Motorlink actuators and controllers were connected to the University's BMS giving it precise control and feedback on the position and status of the actuators.

The actuator you select, therefore, depends on the type of window you are looking to automate. Choose the wrong one and the window won’t seal properly, causing a whole raft of problems.

“In summary,” says Peter, “Windowmaster controls can be simple and basic or complex and programmable. You need to make sure you get one that’s right for your particular circumstance.”

It’s best to seek advice from an experienced provider such as EllisCo early on in a project. They can take you through the various options, advise on how to conceal the cables and whether you need safety features in terms of obstacle detection.

Learn more about the types of actuators on the market and which may be best suited to your next commercial or residential project.