BUILDING MANAGEMENT SYSTEMS


WIRELESS TECHNOLOGY – TH


Intelligent buildings, with their energy-saving capabilities and enhanced comfort, are already a reality. Armin Anders, co-founder & VP Business Development, EnOcean, looks into how wireless technology is offering a flexible solution to meet requirements


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n intelligent buildings, sensors act as the nervous system – capturing data such as temperature,


humidity, presence or CO2 to intelligently control actuators. However, wiring means connecting


these components can be cumbersome and expensive. An alternative and more flexible solution is provided by wireless solutions. 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. But with wireless solutions, sensors for presence, temperature, air quality, light, as well as switches or smoke detectors, can be placed exactly where they are needed. 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 environmental considerations. 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


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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 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.


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 capacitor ensures that the module can bridge periods without ambient energy. When the energy storage is fully charged, the module can operate in complete darkness for about a week without interruptions.


Miniaturised solar modules enable maintenance-free


window contacts, temperature, gas, and humidity sensors, as well as light sensors and presence detectors


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 120µWs, 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. 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.


ENERGY & SUSTAINABILITY SOLUTIONS - Winter 2023


THERMAL ENERGY A significant temperature difference, for instance, between a radiator and its surroundings can provide a lot of energy that can be used not only for sensors but also for actuators. Energy harvesting is done using a Peltier element in combination with a DC/DC converter (EnOcean ECT 310 Perpetuum). Even a small input voltage of 20 millivolts (mV), which corresponds to a temperature difference of about 2˚C, can be converted into a usable output voltage of over 3 V. The larger the temperature difference, the


more energy can be harnessed. This principle is currently mainly used in radiator actuator drives. The energy harvested is sufficient for both radio communication and the actuation changes of the valve. Combined with a solar-powered room sensor, a fully energy-autonomous individual room control can thus be realised. Products with EnOcean technology utilise,


among other things, three different frequency bands that vary depending on the region: 868 MHz in Europe, 902 MHz in North America, and 928 MHz in Japan. Short messages (telegrams) are used for data transmission. These can be verified by the central system using a checksum. Due to the short duration of the telegrams


(about one millisecond) and multiple telegram transmissions, the risk of data collisions is minimised. Interference with other systems


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