• • • SMART BUILDINGS & IOT • • •
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.
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. With the DC/DC converter ECT 310 Perpetuum,
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
battery-free radio modules can also use heat as a power source. In this process, heat – for example, from warm machine parts, radiators, or the human body – is converted into electrical current. 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 such as WLAN or DECT is ruled out since frequencies outside the 2 GHz frequency band used by these devices are employed.
The range is up to 30 meters within buildings, even through walls, and can also be further improved using repeaters. Communication between devices is secured with a 128-bit AES encryption, and the use of rolling codes prevents unauthorised tampering.
Wireless, maintenance-free, smart technology
Manufacturers worldwide have developed thousands of smart products based on battery-free EnOcean wireless technology, such as room thermostats, wireless window contacts, and solar-powered presence detectors. These products not only increase the energy efficiency of a building but also offer high flexibility since no wiring is required for installation. This reduces installation costs and enhances comfort, as the wireless switches can be placed anywhere desired. Another significant advantage is interoperability, as all EnOcean-based products can communicate with each other, irrespective of the manufacturer.
Conclusion
Intelligent buildings, with their energy-saving capabilities and enhanced comfort, are already a reality. By using battery-free wireless technologies, installation costs can be significantly reduced. It’s crucial to choose systems with open standards and flexible ecosystems to ensure future-proofing and avoid potential pitfalls of short-term cheaper alternatives. With the flexibility of these solutions and open
interfaces, smart buildings can adapt to the unique needs of their tenants.
electricalengineeringmagazine.co.uk
ELECTRICAL ENGINEERING • FEBRUARY 2024 33
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