News

14 December 2009

 

Osram retrofits LEDs in period-style lanterns in Regensburg

Germany’s Siemens and LED maker Osram Opto Semiconductors GmbH (a subsidiary of Munich-based lighting manufacturer Osram, which is part of the Siemens’ Industry sector) have demonstrated that energy-saving LEDs can provide authentic period-style lighting for the historical centre in Osram Opto’s home town Regensburg.

The firms have developed a retrofit solution that, they say, meets the requirements of a modern lighting system while preserving the atmosphere of a world heritage site. Discreetly installed in luminaires prescribed by the Office for the Preservation of Historical Monuments, the Golden DRAGON Plus LED light sources target the precise spot they are intended to illuminate, avoiding light pollution, says Osram Opto.

Regensburg has narrow alleys and many winding streets in a multitude of different lengths and widths, so the intricately structured town needs luminaires that enhance its historical ambience, says the firm. To ensure consistently attractive lighting, the different colors of the buildings had to be taken into account and the kind of use, correlated color temperature (CCT) and color rendering index (CRI) adjusted accordingly (e.g. the street lights must not dazzle in residential areas).

With its retrofit prototype based on the Golden DRAGON Plus LED, Osram says that light from the luminaire is fully directed to the exact target area for illumination (e.g. to the street, or also to the façade when it is used to highlight architectural features). Also, the desired level of illuminance and the light distribution can be precisely adjusted by adapting the number, the optical devices and the dimming of the LEDs. The LEDs have a CCT of 3500K and a CRI of 80. A common optical device combines light from the individual LEDs into a single beam and accurately directs it towards the desired target. As part of the project, two alleyways (Blaue Liliengasse and Untere Bachgasse) were fitted with new luminaires and some of the LEDs were selectively directed towards the façade (ensuring that the lighting can be precisely tailored to the architecture).

“This modern lighting solution can be perfectly integrated in the historical centre and offers other advantages, too, such as energy savings, the avoidance of light pollution and optimum façade illumination,” says Alfons Swaczyna, head construction manager & director of the Civil Engineering Office of the municipality of Regensburg. He adds that there are plans to convert most of the luminaires in the town centre to the new technology.

The prototype luminaire allows the replacement of ordinary 90W mercury vapor lamps with LEDs. Manufactured by the Regensburg branch of Siemens, its design is based on a cylinder and can be fitted with different numbers of LEDs on either side, as required (and to produce the desired lighting effect), allowing for completely different light distributions. Up to now, there was an uneven distribution of light, but now a homogenous illumination of about 3 lux has been achieved, says Osram Opto. “We have achieved the same illuminance while cutting energy consumption from 90W to just 42W and additionally integrating façade illumination for historical buildings,” says Dr Martin Moeck, Osram Opto’s project manager for Application Concepts. “There has also been a marked reduction in the direct glare,” he adds.

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