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Industrial Ethernet Book Issue 69 / 43
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Embedded PCs via Ethernet for Building Automation

The new HQ of Danish hearing aid manufacturer Widex A/S boasts a geothermal heat storage system, a wind turbine and solar PV cells. Intelligent building automation ensures efficient use of energy. To manage this, a building automation network (BAN) and over 10,000 data points are controlled by 58 embedded PCs via Ethernet.


Roof-mounted wind turbine. The new Widex A/S HQ building in Allerød, near Copenhagen features various energy-saving and environmentally-friendly facilities. Included is a roof-mounted wind turbine (photo - Proven).

WIDEX A/S HAS been developing and producing hearing aids since 1956 and is today one of the world's leading companies in this field. The company and its 600 employees moved into the new company building in Allerød, Denmark near Copenhagen in 2010 (see next page).

For Widex it was crucial that the architectural appearance should reflect the corporate culture and the company's expertise. Widex wanted to set an example with a CO2-neutral building to show that high responsibility for the environment is both technically and economically feasible. This, the company has achieved (see Box next page).

Green technology combination

Various energy-saving and environmentallyfriendly facilities based on both new and tried-and-tested methods contribute to what is claimed to be the 'uniqueness' of the building. The groundwater heat reservoirbased geothermal system is thought to be the first of its kind in Denmark. Surplus heat is stored in the heat reservoir over summer months, and is withdrawn again in winter when required. The use of geothermal energy reduces CO2 emissions by 70%, which corresponds to a load of 700 tonnes of CO2 each year; equivalent to the emissions typically resulting from 250 gas-heated detached houses. This is a significant saving in both CO2 and energy.

Wind turbine and solar PV

In order to cover the electricity requirements of the 36,600m2 company building, a 100m high wind turbine was erected on the company site. The wind turbine produces an annual 3.4 million kWh of electricity and saves nearly 1900 tonnes of CO2 each year, which corresponds to the electricity consumption of 650 detached houses (without heating).

The wind turbine supplies more electricity than Widex can use in total. The surplus power is fed into the local grid, therefore making a contribution to this environmentally friendly region. Around 20,000 solar cells fitted on to the south facade of the building produce approximately 34,000kWh of additional electricity.

Temperature, CO2, light and motion sensors were installed. The lighting, with different lighting scenarios, is controlled by the embedded PCs via a DALI bus (see the Box opposite). Around 4000 DALI slaves are distributed throughout the building.


Building automation for hearing aid manufacture. The new Widex A/S HQ building in Allerød, near Copenhagen benefits from an embedded PC-based intelligent building automation system. Over 10,000 data points distributed throughout the entire building are controlled by 58 CX1020 embedded PCs via Ethernet (photo by Widex).

Individual control

The building's various technical installations are controlled by a total of 58 CX1020 embedded PCs from Beckhoff. The equipment in the various floor sections is controlled by a CX1020 embedded PC, which is connected via Ethernet to 12 decentralised I/O terminal stations. The 600 bus terminals distributed throughout the entire building control 10,643 data points.

The scope of control covers the following functions: ventilation and air conditioning (HVAC), burglar alarm and light control.

Radio technology

The light switches are integrated via EnOcean1 radio technology. Beckhoff's EnOcean bus terminals convert the received signals and forward them to the embedded PC. The application of radio switches offers Widex space utilisation flexibility and reduces the lifecycle costs of the building. Future changes in use of space will not need time-consuming recabling - only software modifications.

Lighting control

Light control in the space is based on motion sensors that monitor movements during the working day. Light sensors monitor insolation through the windows; if this is bright enough, the lights near the windows are either dimmed or completely switched off.

In the evenings, when all employees have left the building, motion sensors switch over to burglar alarm mode. After the last employee has left a building section, a loudspeaker announcement is made 10 minutes later informing that the alarm will be activated after a further 10 minutes. In addition, the entire electricity supply to the section concerned is switched off after this time has elapsed.

Only the power supply to refrigerators etc is maintained, so that the energy consumption of the building is minimised during the night.

Individual ventilation

To provide comfortable ventilation for the building occupants, air exchange and circulation in each room is individually controlled, and - if necessary - via a CO2 sensor connected to the embedded PC.

There are no supply air anemostats in the rooms as is otherwise usual; instead, the air is fed outside via a ceiling grille and is cooled or heated by a separate ventilation device. This fancoil ventilation unit is installed within the suspended ceiling.


Embedded PCs are the basis for control. In this Widex HQ application, the new building's various technical installations are controlled by 58 CX1020 embedded PCs from Beckhoff. Each floor's installations are controlled by an embedded PC, which is connected via Ethernet to 12 decentralised I/O terminal stations.

SCADA for monitoring

All building functions, as well as the wind turbine, the solar PV system, the compressed air compressors, the geothermal heating/ cooling system and the HVAC system (Beckhoff PCs) can be controlled and monitored by the works personnel using a SCADA system. This way it is possible to see which employees are in the building at any time.

About the DALI protocol

The Digital Addressable Lighting Interface (DALI) is an important standard (effectively the de-facto standard) for network-based systems controlling building lighting. It is an open standard alternative to Digital Signal Interface (DSI), which it has been based upon.

DALI is specified in IEC 60929 (for fluorescent lamp ballasts), and it covers the electrical interface for a building's various lighting control networks and the communications protocol used.

In operation, a DALI network comprises controller, lighting ballasts and dimmers, each having its own DALI interface and unique address. Devices are individually addressed, and each lamp is monitored and controlled via bi-directional data exchange. In addition, broadcast messages can simultaneously address a large number of devices.

As many as 64 lighting devices can be addressed in any given system, but DALI can also be used as a subsystem via DALI gateways to address a significantly greater number of lighting-based devices.

Data transfer (Manchester encoding) between controller and devices is via an asynchronous, half-duplex serial protocol over a two-wire differential bus. The data transfer rate is 1200 bit/s.

A single pair of wires forms the bus for communication to all devices on the network, which can be bus or star topologies, or a combination of them.

DALI systems can be installed next to mains cables or within a multi-core cable that includes mains power. A high signal to noise ratio allows reliable communications even in very electrically noisy environments.

DALI devices store configuration data in RAM during normal operation, in preference to EEPROM (but this is patented).

1Together with its partners, EnOcean (www.enocean.com) promotes the worldwide use of self-powered wireless switches, sensors and controls for building automation systems.

www.beckhoff.com


Source: Industrial Ethernet Book Issue 69 / 43
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