Luminaire Efficiency – A Proposal to Think Different
LED-technology is being utilized in more and more areas. Tunnel lighting for example is an extensive field for the application of LED-technology especially in countries with alpine terrain, like Austria and Switzerland. Good reliability and a sustainable energy balance are only a few arguments for the replacement of traditional lighting systems. Therefore, increasingly more tunnels are equipped with new LED-luminaires, for example the Pfänder-Tunnel and the Arlberg-Tunnel, which are both extremely important for the region around Bregenz.
When designing optical systems for tunnel luminaires many criteria must be kept in mind: a lighting design must reach requirements regarding homogeneity, luminance and threshold increment, and still handle the challenging environmental conditions that are found in tunnels. With the increase of LED efficiency also luminaire efficiency is an important benchmark for the assignment of most public contracts, especially since this value is understood well by non-lighting related professionals. Minimum values are now even defined in public regulations like the Austrian regulation PlaPB800.562.1000 of ASFINAG (the Austrian infrastructure corporation). Unfortunately, the focus on this specific value easily leads to wrong conclusions regarding energy saving as it only considers a single luminaire instead of the whole lighting system. Clearly luminaires without any specific optical system can perform better in terms of luminaire efficiency compared to luminaires with specifically designed lenses. Nevertheless, the overall energy management of a tunnel lighting system is more sustainable when luminaires are used whose optical systems have been optimized for that purpose.
Our talk will show the challenges in designing tunnel luminaires and explain, how a good optical design can help to achieve all necessary requirements. We would like to address this issue based on significant tunnel lighting projects in Austria in the last years.
Additionally, we would like to discuss possible alternatives for future tender specifications that would lead to a more sustainable award of contract.