Combining the benefits of wireless sensors and IP
Seamless integration of energy-harvesting wireless technology in IP networks creates whole new possibilities for building automation, as Graham Martin explains.
Internet protocol (IP) has now become a worldwide standard for data communication between all manner of devices over the Internet. There is much discussion surrounding the idea of assigning every outlet and every filament lamp its own IP address and then connecting them over the Internet. What many do not know is that today already all electrical loads can be addressed over an IP network — enabled by batteryless wireless technology and matching access points.
EnOcean's wireless solutions harvest the power they need from their surroundings — from motion, light or temperature differences —enabling entirely energy-autonomous and maintenance-free automation applications. Power obtained from the surrounding environment suffices to transmit a wireless signal and, for example, turn on a light. Teamed with the TCP/IP protocol the user can take advantage of the possibilities provided by established building-automation systems. Wireless technology without batteries means cost-savings in installation, huge simplification of the cabling of a building and flexible configuration of space — because no new cabling is needed if room divisions are altered later.
To give an example, with the intention of adding a new building to a retirement home, the operators envisaged the following.
• No light switches in the entire building.
• Numerous, easily accessible and batteryless emergency buttons.
• Automatic turn off of electric loads in apartments when occupants are absent.
• Control by staff using a smartphone or iPad.
They also wanted staff to be able to receive alarm messages during the night from the adjoining building complex. Subsequently, the operators were sold on the idea of being able to implement all this using a straightforward, batteryless wireless solution.
In the initial installation phase, wireless technology is installed in the new building of the retirement home. Following that stage comes the conversion of existing, adjoining buildings. All public areas will be fitted with combined presence sensors for light and temperature. These, together with LED beamers, will ensure that lighting is always optimal in corridors, recreation rooms, restrooms, kitchens, cafeteria and other spaces in the buildings. At the same time, these presence detectors will save energy because lights are automatically turned off in unoccupied rooms. When a carer or resident enters a room, light will be increased sufficiently to produce optimum visibility.
In the future, the apartments will no longer have mechanical keys. Every resident will be given a plastic card integrating an individual, contactless RFID chip that opens the door to the resident's own apartment as well as to all public areas.
The cards of carer staff have extended rights.
When a resident is in their apartment, they only have to insert the chip card in the holder next to the door and electrical appliances will be powered immediately. Removing the card will turn off lights and critical loads such as a cooking hobs. Electrically powered shutters outside can also be automatically manipulated. The wireless technology and visualisation software enable staff to supervise the status of all loads, as well as windows and doors, so they know at all times which windows and doors are open, how warm it is in individual apartments and whether shutters are up or down. In this way, any serious deviation from normal daily routine becomes visible. For residents, this supervision is unobtrusive, and assures maximum, comfort, convenience and security.
To fully automate the retirement home, software from BSC Computer, with its high-grade and stringent IP-oriented architecture, is required. The software allows an unlimited number of sensors to be linked and is easily expanded. Installed on all floors of the new building are EnOcean access points with a LAN interface. These have their own processor and memory for 3000 EnOcean telegrams. In this way no sensor signal is lost, even if the network or the building computer suddenly or briefly fails.
An access point uses TCP/IP, not a Com interface over the Ethernet. The system can consequently work at a high processing speed, even on a large number of sensors. Every action is saved in an SQL database, documenting, for legal certainty, the time between an emergency call and the arrival of a carer. Access points are located on the ceiling in the corridors, and each covers an area of about 750 m2. They communicate with the central processor by Cat7 Ethernet LAN.
The local networks of the individual buildings are independent of one another, and each has its own processor for safety reasons. An encoded IP link enables the networks of the two buildings to connect to one another. That satisfies an important customer requirement that if the night-time carer in one building is busy with an occupant, the staff of the other building can take over supervision on their monitor.
Another major component is iPads for the staff, joined by WLAN to the overall system. That enables all chores to be handled with a single device, including retrieval and updating of resident documentation, ordering of material, selection of midday menu, telephony by SIP protocol, building management plus visualisation of corridor and door cameras.
The operator intends to implement this innovative technology in other residential homes in the European Union. Given the European-wide availability of smart meters for electricity, gas, water and district heating, such batteryless sensor networks can easily handle other tasks. They are ideal for metering consumption data and sending them to a central interface. The BSC software monitors and displays meter readings and compares them to set figures. All terminal devices (meters, sensors and actuators) can then be connected to a wide-area interface and the data delivered to the utility over the Internet. Both access and data communications are secured by a high degree of encryption.
Together, EnOcean technology and IP create perfect solutions. EnOcean-enabled devices are highly flexible in their positioning and maintenance-free, needing neither cables nor batteries. They possess a unique ID address, so they can be integrated seamlessly in an IP network through an access point. That eliminates any elaborate, extra web-server solutions for each sensor and actuator, which would be needed for native IP addressing of sensors and actuators. This means a legacy network can be easily merged with energy-harvesting technology to benefit from all the attractive advantages. The user is rewarded with more flexibility, comfort and convenience, accompanied by low installation costs and reduced power needs.
Graham Martin is chairman and CEO of EnOcean Alliance.
