Whether room climate, lighting or fresh air - in an optimally networked building, everything should be adapted to current requirements in an energy-efficient manner and in real time. To achieve this goal of building automation, a large number of sensors and actuators are required, which are often digitally networked due the increasing complexity of the systems.
In more and more building automation systems, sensors and actuators communicate with each other via digital protocols. Generally, a distinction is made between proprietary systems and open systems. Especially in large properties, the use of standardized automation protocols is worthwhile, so all components of the system can communicate with each other "barrier-free" and the "translation effort" is kept to a minimum. Furthermore, the interoperability of the open systems is a decisive purchasing argument for operators. Since the protocols are offered by many well-known manufacturers, the plant operator remains independent in the choice of his field devices.
BACnet stands for "Building Automation and Control networks" - a network protocol for building automation that is mainly used in large properties and functional buildings. The most important difference to other protocols: BACnet is object-oriented. In a BACnet object, several pieces of information (so-called "properties") such as maximum value or alarm value can be assigned to an object, whereas e.g. with KNX or ModBus, only the existing value ("Present Value") is specified as a data point. Since BACnet is mainly used in the management and automation level, it builds on existing technologies and usually uses the Ethernet/Internet Protocol (IP) as a transmission medium, which means that it can also communicate easily via the Internet. BACnet is then often used as a higher-level system in large installations and combined with KNX or LonWorks at the field level.
KNX is a widespread international standard, which is used in home and building control for networking sensors, actuators, control and regulation devices, as well as operating devices. While KNX was initially used mainly in commercial buildings, the standard is also becoming increasingly important in the automation of private apartments and houses. The interoperability of KNX can bring cost advantages, especially when networking different trades such as heating, ventilation, blinds and lighting. According to surveys by the British BSRIA, KNX has a market share of about 50% in Europe. More than 500 device manufacturers are now listed as KNX partners, and the trend is rising. The basis for this is the technical further development of the standard. Whereas KNX used to be a two-wire bus, it has now been supplemented by the transmission media Ethernet/Internet Protocol (IP), Powerline and radio. Especially in the field of radio transmission KNX is facing strong competition.
Self-sufficient multisensor EMSIA from EnOcean with integrated solar cell for measuring temperature, humidity and acceleration.
Especially in the area of light switches or other actuating elements, self-sufficient systems that are neither externally supplied nor communicate by wire are being used more and more frequently. The advantage is obvious: the elimination of wiring saves time during installation, maintenance and material costs. In addition, no external power is required, making operation maximally energy-efficient. One example of this is EnOcean. EnOcean is a standard maintained by the EnOcean Alliance based on the 868 MHz radio bus system. Studies by the EnOcean Alliance show that energy savings of up to 30% can be achieved in buildings when EnOcean technology is used. EnOcean devices draw their energy from the environment. Whether drafts, temperature differences or light - every possible energy source is used to operate the sensors without batteries. EnOcean is growing strongly and now has over 300 manufacturers listed as partners.
Where this technology is headed does not yet seem to be clear. In the face of climate change and the rapidly increasing requirements for energy-efficient buildings, self-sufficient wireless sensors offer the most promising technological outlook, as they can be operated in a completely CO2-neutral manner. The decisive factor will be to what extent the requirements for precision, low power and cost can be reconciled to create marketable products that appeal to a broad international market.
Gebäudeautomation – Kommunikationssysteme mit EIB/KNX, LON und BACnet | Merz H., Hansemann T., Hübner C. | Hanser Verlag, 3. Aktualisierte Auflage, 2016