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WE-EF’s LED luminaires help German city reduce power consumption for public streetlighting

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LED street lighting and area lighting luminaires from WE-EF LIGHTING Pty Ltd have helped the German city of Bielefeld reduce its power consumption for public streetlighting by 1.8 million kWh per year. 

The city carried out an extensive retrofit by replacing 5,889 existing luminaires with modern WE-EF VFL540 LED street and area lighting luminaires, providing the city with considerable gains in terms of energy savings, CO2 reduction and light quality. 

In 2010, Bielefeld was still operating some 16,000 streetlighting luminaires with mercury vapour lamps. Though compact fluorescent lamps (TC-L) and metal halide lamps were used as an alternative when repairs or replacement were necessary since 1999, almost 50% of the city's streetlighting still relied on mercury vapour lamps.
 
The binding introduction of the European Union Regulation 245/2009 (Eco-Design Directive), which prescribed that mercury vapour lamps may no longer be brought into circulation as of April 2015, created an urgent need for action and prompted the city to immediately prepare a concept to implement these requirements. 
 
Bielefeld began to focus on LED technology motivated by the considerable energy savings, which would lead to more cost-effective and ecological operation of streetlighting systems, together with much lower maintenance costs. The city was also able to partially cover the investment costs for the technology with subsidies from a special programme of the Federal Ministry for Environment, Nature Conservation and Reactor Safety (BMU).
 
WE-EF won the public tender with its VFL540 LED luminaires. Since Bielefeld was required to access all subsidies in the current budget year, the entire project had a very tight time frame that required 5,890 luminaires to be delivered within six months. WE-EF was able to meet the challenging delivery schedule with 100% reliability. 
 
The WE-EF LED luminaires have a nominal power input of only 21 W, compared with 89 W of the original mushroom-shaped opal glass luminaires. Thanks to their tailored optical components, the LED luminaires deliver significantly more light to the target area and prevent unnecessary light spillage. Compared to the original mushroom luminaires with their concentric light distribution around the pole that added only 0.1 lux to the roadways from a distance of 12 metres, the new LED luminaires generated at least 0.2 lux on the edge of a significantly bigger 12 x 35 metre evaluation field.
 
WE-EF also offered a cost-effective and aesthetically attractive solution for extending the existing luminaire poles by 1 metre or 1.25 metres to a height of five metres to achieve the optimal light distribution. 
 
On main and residential streets, which are generally 8-10 metres wide, the installed VFL540 LED luminaires fitted with S70 lenses provide significantly more illumination across the width of the road. 
 
Another advantage is in the improvement of the uniformity of lighting with the distance between the poles ranging from 35 metres to 40 metres providing very good longitudinal uniformity as well as high overall uniformity on the road surface. This also helps to eliminate dark zones that can put pedestrians and bike riders on the edge of the road at risk. 
 
Additionally, the precisely defined distribution prevents unnecessary light spillage. Dark sky concerns are also more than satisfied by WE-EF luminaires. 
 
WE-EF engineers developed an appropriate solution with two additional LED modules integrated into the luminaire for lighting up footpaths wider than two metres. The modified luminaire type, now available with a connected rating of 32 W was installed at 130 locations to provide better visual conditions.
 
The VFL540 LED version was also adapted for streets wider than 12 metres. Though generating considerably higher illuminance than the original mushroom luminaires on the opposite footpath, a slight improvement was achieved by integrating an S60 lens before the two centre-front LED modules in the luminaire. 
 
As with any renovation project, the retrofit process in Bielefeld will also require the ability to adapt to the structural conditions that have evolved over the years. According to Mark Malitzki, who is responsible for the Bielefeld project at WE-EF, in the final analysis, the retrofit brought about objective advantages in all cases. While dark zones do occur in situations in which there are very long distances between poles, overall visual conditions are much better than before, as the lit areas are now much brighter.

Hans-Werner Schuette from the Bielefeld transportation authority concludes by saying that the retrofit has resulted in significantly reduced energy costs and CO2 emissions in addition to improved light quality.

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