In control: A smarter approach to window automation

Tom Lymn, Director of Sales, WindowMaster

From sustainability, carbon reduction and energy efficiency to pandemic resilience and making buildings healthier and more pleasant places to be, there are lots of reasons we’re seeing a growing interest in window automation.

Along with the human benefits, such as minimising the risk of disease transmission and reducing symptoms of Sick Building Syndrome, natural ventilation (NV) decreases reliance on mechanical systems, lowering carbon and running costs. When properly designed and automated, it enables key ventilation strategies, such as purge ventilation, night cooling and pre-empting poor room conditions.

To help your NV system work in harmony with other building functions, like heating and mechanical cooling, keep occupants comfortable and ultimately save cost and energy, it needs to be properly controlled.

Out with the old

A typical approach to automated natural ventilation comprises the building management system (BMS), the weather station and room sensors to monitor conditions inside and out, a keypad input to the BMS allowing user override, a raise-lower device and a power supply – for each bank of windows. On the surface, it’s relatively simple, but with more than one bank of windows, it quickly becomes very complex with a lot of different components, requiring considerable design work, maintenance and additional devices for monitoring.

Furthermore, operational tolerances for a traditional 0-10v approach, with lots of devices across lots of field cabling, means there is often less accuracy with window positions.

Fortunately, modern controllers are available which bring a level of precision, monitoring and simplicity, unattainable with traditional systems.

In with the new

Offering a higher level of building performance, the latest technology consists of network-based controllers and power supplies which can handle native BACnet, KNX or Modbus communication and are useable with any 24v DC actuators.

Allowing you to replace 25 individual components with one element, modern controllers, such as WindowMaster’s MotorLink®, save cost and design time while delivering performance gains, simplifying the system architecture considerably.

Banks of windows and keypads are wired directly into the controller, which is assigned its own IP address, and the controller is in direct communication with the BMS network, using simple percentage position commands to control the groups of windows over the network.

Each controller has up to 10 motor outputs, or ‘motorlines’, each of which can connect to up to 4 actuators. The motor outputs then have unique objects for each of their functions, such as auto-positioning according to the BMS logic, based on the room sensors, CO2 levels or temperature. Another common object is maximum position: a set percentage opening, which prevents openings under certain conditions, past a certain limit.

Under control

Let’s take an office for example, with windows on its façade and roof lights in the ceiling. As the CO2 in the room increases, the BMS sends commands to the relevant controller IP address and opens the façade windows to 10% and the roof lights to 20% open.

Later, the external weather sensors indicate it’s starting to rain. To prevent water ingress, the BMS sends commands to close the façade windows to a 5% position and the roof lights to 0%, or closed. The max position object sets a temporary limit on the opening allowed and can prevent manual override so people don’t open the roof lights when it’s raining. When the rain stops, the BMS can remove the limit and rewrite the max opening to a different amount.

At the end of the day, the max limit for the façade windows might be 0% for security purposes, while the limit for the roof lights is at 5% to support night cooling.

Efficient and accurate automation

Using the right technology to enable your windows and BMS to communicate with one another will take the potential for natural ventilation in your building to the next level. Along with allowing for minimal disruption through quiet background automation, intelligent reactions to changing conditions and improved security, appropriate technology helps to optimise setpoints to achieve best performance while complementing energy use of other building systems.

This is key; if you can monitor it, you can manage it – and going forward this will be a major factor in achieving acceptable standards of air quality, wellbeing and a MUST toward our carbon reduction goals.

For more information about WindowMaster’s MotorLink® controllers, visit www.windowmaster.com.