Mean & Green

Posted on 9 Jun 2009 at 17:20

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The KNX (UK) Association, a partnership of UK manufacturers, integrators and training establishments, gave an example of how a KNX system can save energy by controlling a home's lighting. "A lighting control system can be simply configured to put the lights on only when someone is present in the room, and can monitor natural daylight levels to dim or turn the lights off when enough ambient light is present," explains a KNX spokesperson. "It is a very simple example of preserving energy, but drive through any financial district at midnight and you will see that there is an awful lot of energy that could be preserved by employing these simple measures. Effective use of lighting control alone can result in energy savings of up to 30 to 40 per cent."

Street Lighting

Although KNX is usually thought of as a technology for intelligent buildings, whether they're homes, offices, factories or airport terminal buildings, it can do more. A KNX system for controlling street lights in the Austrian city of Salzburg received an award recently. Salzburg covers an area of 65 square kilometres and has 150,269 inhabitants. The public lighting system incorporates 19,000 street lights plus 200 floodlights that illuminate 30 different sights, including the Hohensalzburg castle and the hills immediately surrounding the city. Before the introduction of the new system, power consumption stood at 2.9 megawatts. This figure is set to fall significantly.

The new KNX system switches lights on in the evening and off in the morning at precise ambient light levels, as measured by sensors around the city. A so-called 'long time mode' stops the lights coming on for very short periods during bad weather such as thunderstorms or dark clouds. The intelligent system checks the light development over Salzburg and switches the lights on only after an extended period of darkness. This greatly extends the life of the mercury vapour and sodium lights. It also reduces the voltage of the street lights to 180V after midnight in certain areas, dimming them and reducing their energy consumption.

The German town of Lemgo has developed an alternative strategy to reduce the energy consumption of street lighting, and several others have since adopted the system. In some German towns it has become common practice to save energy by turning off street lights after 11pm. Needless to say, this policy has come in for criticism from local communities concerned about its impact on public safety. The system now in use in Lemgo provides light for pedestrians who are out late at night, while still making a considerable energy saving. The system, called Dial4Light, allows a subscriber to send a text message containing the serial number of a street, which turns on the lights along that street for 15 minutes.

Advanced technology is being developed to tackle energy waste and, as a result, future generations may be able to enjoy a high quality of life without threatening the planet. In the meantime we can say that, while virtually everything we do will have an impact on the environment, intelligent systems are doing their bit to minimise that impact.

Author: Mike Bedford