• • • SMART BUILDINGS & IOT • • •
Wireless technology – the key to smart buildings
Armin Anders, co-founder & vice president of business development at EnOcean GmbH, says that in recent years, wireless technologies have established themselves as the preferred solution in both building automation and smart homes
Furthermore, battery-free wireless solutions eliminate the need for ongoing maintenance, reducing operating costs.
T In an intelligent building, sensors act as the
nervous system capturing various data such as temperature, humidity, presence, or CO2 to intelligently control actuators. However, connecting these components can be cumbersome and expensive due to the need for wiring. Wireless solutions provide the required flexibility, especially during renovations. While some wireless solutions dependent on batteries require intensive maintenance, are more expensive, and create hazardous waste, those without batteries offer significant advantages.
Maximising flexibility with wireless
When it comes to integrating numerous sensors and switches into a system, wired solutions are impractical. It’s costly and inflexible to connect each sensor with its own wire. Wireless systems offer a solution.
Sensors for presence, temperature, air quality, light, as well as switches or smoke detectors can be placed exactly where they are needed without the constraint of cables. The strength lies in the ability to expand the system with new products and additional sensors without the need to break walls. Wireless sensors and switches minimise coordination among various trades and reduce the interference in existing building structures. For instance, when repurposing an office building, there’s no need to break walls for cabling or place power lines inconveniently. This saves costs and is more appealing to building owners or future occupants.
Sustainable operations without batteries
A significant drawback of some wireless solutions is their dependence on external power sources or batteries for the energy required for sensors and communication. This results in increased maintenance costs and environmental concerns. In practice, batteries often deplete faster than their theoretical lifespan and need to be replaced by professionals annually. The replacement of batteries not only involves labour but also
32 ELECTRICAL ENGINEERING • FEBRUARY 2024
hese technologies offer more flexibility during planning and save on the cost and hassle of extensive wiring during installation.
environmental considerations since batteries are hazardous and must be disposed of properly. With a large number of wireless sensors – in an office building, this can quickly amount to several thousand – the process of battery replacement and disposal can easily become a full-time job for a facility manager, from access coordination, device localisation, battery exchange, device testing, documentation, battery storage, and finally to disposal.
Energy harvesting Modern systems leverage battery-free wireless components, offering a reliable and maintenance- free alternative to traditional wired solutions while retaining the flexibility and easy retrofitting of wireless systems. Products with battery-free wireless technology harness the energy available in their immediate surroundings—a concept known as energy harvesting. Three main forms of energy harvesting have emerged in building automation: kinetic, solar, and thermal energy.
Kinetic energy
Motion is a dependable energy source for various switches. A single press generates enough energy for three wireless messages. An electromechanical energy converter (EnOcean ECO 200) inside the switch housing converts the button press into electrical energy, making it available immediately after activation.
The energy converter works similarly to a bicycle
dynamo, where a small but powerful magnet drives a magnetic flux through two magnetically conductive anchor plates, which closes in a U-shaped core. An induction coil is wound around this core, which can be put in two positions where
These sensors have swell disks at the bottom that expand when they come into contact with a liquid. This movement triggers the electromechanical converter and sends a radio signal. Due to this message, the line’s valve automatically closes, and the building owner or facility manager receives a corresponding notification, for example on their smartphone.
Solar-based energy
Thanks to miniaturised solar modules, it’s possible to power radio modules with electricity even with low interior light intensity. Solar-powered sensor modules operate extremely energy efficiently. A temperature reading that is to be transmitted every 15 minutes requires only 3.6 hours of charging time per day at a brightness of 200 lux for uninterrupted operation. At this brightness, the solar cell produces a voltage of 3 V. An additional Poly Acenic Semiconductor (PAS) charging
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it touches the respective opposing anchor plates. This movement results in a sudden change in the magnetic field, thereby producing a voltage pulse in the induction coil.
ECO 200 is an energy converter for linear movement. Possible applications include miniaturised switches and sensors in building technology and industrial automation. A single switch actuation generates an energy amount of 120 µWs, sufficient for three radio messages. At room temperature the electromechanical energy converter allows over a million switching cycles. The principle of kinetic energy harvesting can also be used for light or blind switches. Additionally, there are battery-less sensors that can warn of water damage.
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