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Wireless Communications

Self-powered wireless technology for green buildings

In a building that could do with renovation for example, heating and water can even account for as much as one third of facility operating costs. Modern heating regulation governed by time of day and room temperature can save a lot of money in both residential and office buildings. Properly controlled networking of heating, air-conditioning and lighting has now become standard in new buildings. If older buildings are to be operated economically and ecologically friendly, outdated installations need to be replaced or retrofitted with energy-saving technology.

Although a retrofit will generally involve considerable effort and expense. You have to drill holes in walls and lay whole meters of cabling, creating noise, dust and dirt. So it can hardly be undertaken while a building is occupied by people trying to concentrate on their job. There is consequently increasing focus on high-performance, wireless systems with minimal power consumption that are simply and speedily installed, and without drilling any holes in walls to route cables. EnOcean technology for example.

Harvesting power from surrounding energy
The innovative technology from EnOcean works entirely maintenance-free without batteries. By detecting information and then transmitting it by short-range wireless, the idea behind the EnOcean solution is to harvest the necessary power from its surroundings: from linear motion, light or differences in temperature, for example. The amount of energy obtained in this way is enough to send a wireless signal, and turn on a light for instance. Plus, the use of wireless switches and wireless sensors greatly simplifies the cabling of a building. At the same time they allow huge flexibility because no new cabling is needed if future alterations are planned. With little effort and with no interference with walls, EnOcean-enabled products can be placed on any surface in any room space where they will be of optimum use.

EnOcean technology is characterized by efficient energy converters, ultra-low-power electronic circuitry and a reliable wireless protocol. The wireless signal is transmitted in the 868 MHz or 315 MHz frequency band, meaning it fits into a broad range of products worldwide. The telegrams are just one millisecond long, which is approximately one hundred times shorter than the signal of a conventional wireless switch.

Installation and parallel operation of hundreds of wireless switches and sensors in restricted spaces is straightforward. To exclude transmission errors, a telegram is randomly repeated twice in the space of about 30 milliseconds to significantly reduce the probability of collision. The range is 300 meters in the open and up to 30 meters inside buildings. Each EnOcean module comes with a unique 32-bit identification number to exclude any possibility of overlap with other wireless switches.

Telecom Italia modernized its headquarters with self-powered devices
The EnOcean technology has been successfully deployed in over 100.000 building projects. One example is the headquarters of Telecom Italia, the country’s leading telecommunications provider. Established in 1994 and headquartered in Milan, the company operates the larger part of Italy’s landline network with internet services, and is also the major Italian cellphone provider through its affiliate Telecom Italia Mobile.

“Pivotal for selecting EnOcean-enabled products was the flexibility and speed of installation you get from self-powered wireless technology”, says Dr. Diego Cattaneo, product manager of Siemens Building Technologies Division, the partner responsible for implementing the project. “That enabled us to modernize the eight-floor building in next to no time – without having to interrupt regular, day-to-day operations.”

To make the eight-floor corporate headquarters – with more than 40 offices on each level – more economical in operation and more comfortable and convenient in subsequent use, the telecommunications enterprise decided to modernize its old HVAC plant and link it to a central control system.

The first step was to replace all existing fan coils. This meant removing about 1000 old units. Modern electric fan coils were installed in their place and connected to Siemens RXC21.1 room controllers. These enable automatic control not only of fan coils but also of chilled ceilings and radiators in individual rooms. The next step was to install 200 SRC04-FTT EnOcean/LON gateways from Thermokon, which were then tied to the LON bus. The building contains a total of 14 vertical LON bus routes. Finally 600 Thermokon SR04 PST room temperature sensors were installed, with setpoint and fan level setting. The batteryless room sensors regulate temperature and ventilation in the individual rooms. Information is transmitted to receivers by EnOcean standard wireless telegrams. A solar-powered energy storage mechanism makes operation service-free.

All system components are integrated into the Siemens DESIGO building automation system. An open platform makes DESIGO compatible with all existing and future systems and components. So it is possible to both continue using ready products and integrate new ones. The automation system supports Ethernet TCP/IP, OPC, BACnet, EIB, LonMark, PROFIBUS, the telephone network and the internet. A further advantage is that the entire installation can also be controlled from a PC – by the DESIGO INSIGHT management station.

Installing the 800 self-powered devices proved to be very simple. The modernization work only took about three months. Renovation was undertaken while the company continued to operate, without disturbing its employees. The old fan coils were replaced during the night. Installation of the controllers in the various offices was possible during the day however, because no cabling had to be laid for the purpose.

Innovative technology in its corporate headquarters enables Telecom Italia to offer its people more comfort and convenience, and at the same time to cut power consumption by matching it to real needs. Then there is the attractive flexibility of installation that comes with the technology. With little effort, and without damaging walls, it was possible to fit the wireless sensors speedily and simply, precisely where they are of optimum benefit. “Not forgetting the cost savings on installation and any future renovation compared to a cabled solution”, adds Dr. Cattaneo.

Future-proof deployment in new applications
The first generation of EnOcean technology was built using numerous discrete components. However, the introduction of a new system architecture – EnOcean Dolphin – based on a sophisticated, power-saving custom IC, unites wireless technology and programmable digital electronics in a single, ultra-compact, low-power, low-cost unit. By supporting energy-autonomous actuators, bidirectional communication with sensors, and innovative routing concepts, this platform creates the foundation for a wide variety of new products and applications.

The Dolphin modules (STM 300, TCM 300 and TCM 320) can be programmed for custom applications through the API interface. The STM 300 scavenger transceiver is excellent for implementing energy-autonomous applications to sense temperature, light or air quality, for example. The TCM 300 and TCM 320 transceivers on the other hand are best suited for use in line-powered components such as flush-mounted actuators, repeaters or gateways.




All Dolphin modules come with standard firmware for building automation. However, users can also create their own firmware. This is transfered to a specific wireless module by Dolphin Studio software and the programming adapter.

Recent innovations based on the EnOcean Dolphin platform include for example bidirectional, self-powered room temperature sensors that are not only capable of transmitting measured values of temperature and humidity but that can remain awake to receive a message such as a new temperature set point or feedback information to present on a display for the user. This allows a living-room sensor to indicate whether a window has been detected as being open, for example, so that the heating or air-conditioning can be adjusted accordingly.

The platform has also enabled ultra-low-power timers that enable devices such as radiator actuators to obtain their settings in cycles from a central station but require no energy source to be connected and instead draw their energy from the difference in temperature between the heating and their surroundings.

In the future, through further development of EnOcean communication, it will be possible to wirelessly control a heating radiator valve.

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