Professor Georges Zissis, a world expert in LED technology – and in particular its application for street lighting – delivered seminars in February to over 360 lighting and other professionals in Sydney, Melbourne and Brisbane.

The seminars were part of Lighting Council Australia’s LED Seminar Series and came at a particularly important time for lighting when cities, municipalities and utilities around the world are moving, or contemplating the move, to LED street lighting.

Professor Zissis is eminently qualified to speak on the subject of solid state lighting. He is head of the Light and Matter Research Group at LaPlaCE (Laboratoire Plasma et Conversion d’Énergie) at the University of Toulouse, France, and is a world-renowned expert in lighting systems research and design.

In addition Professor Zissis is Task 1 Leader of the International Energy Agency’s 4E SSL Annex. Under his leadership, the IEA has published performance tiers for a range of applications. The SSL Annex was established in 2009 under the framework of the International Energy Agency’s Efficient Electrical End-Use Equipment (4E) Implementing Agreement to provide advice to its 10 member countries – one of which is Australia – seeking to implement quality assurance programs for SSL lighting. The goal of this work is to reduce the risk in using SSL products and to provide Governments and consumers with recommendations they can trust when investing in SSL products. The performance tiers identify a suite of metrics and values related to minimum performance values of SSL for energy efficiency, lighting quality and safety.

LED seminar series

In his Australian seminar titled LEDs – Dreams and Nightmares, Professor Zissis characterised the advantages of LEDs as high luminance, excellent colour saturation, high luminous efficacy, high energy conversion efficacy, small dimensions and light weight, robustness, long lifespan, low voltage power supply and ease of dimming.

However his presentation went on to document some of the issues and problems with the technology. These included:

• eventual limits to efficacy of around 250 lumens per Watt estimated to be reached in 2025
• a marked difference between LED efficacy and system efficacy arising from thermal management losses, optical losses, ballast losses and photometry losses
• marked variations between claimed and tested performance
• falsification by some vendors of test certificates
• a multiplicity of conflicting standards
• issues with power supplies which include poor manual soldering, unreliable wiring, low quality components, low quality chemical capacitors, hot points and low mechanical quality
• power factor and cosφ issues
• flicker
• blue light hazard
• environmental impact

Energy consumption during operation is considered by Professor Zissis to be by far the most important environmental indicator of light sources. By this measure LEDs perform well.

In the second seminar of the series, Professor Zissis examined the current status of street lighting. He spoke of the ‘Grenelle I’ (2009) and ‘Grenelle II’ (2010) French laws which had the following aims:

• Replacing old technologies with modern lamps
• Promoting LED technology
• Regulating mains quality & reducing cosφ impact
• Promoting power variation systems
• Promoting electronic ballasts
• Turning-off lights during late at night
• Enhancing preventive maintenance
• Converting traffic lights to LEDs

The legislation has resulted in a saving of 19.55 GWh spread across 2,131 small French communities with a total population of 1.7 million inhabitants.

Among the conclusions of the street lighting seminar is the need to take a holistic approach to energy savings. Factors including mesopic vision, lamp technology, intelligent control and fixtures all need to be considered.

Induction lighting was considered a particular problem unless adequately shielded because of its potential to cause electromagnetic interference.
Professor Zissis demonstrated the effects of mesopic vision under dimming conditions and showed an excellent example of LEDs replacing older technology on a pedestrian bridge spanning environmentally sensitive wetlands in Portugal.

Professor Zissis questions whether LEDs are ready for road lighting (as opposed to the less demanding requirements of street and other public lighting). In a 2011 experiment only one supplier’s product was deemed to meet all requirements (which included illuminance levels, light uniformity and energy efficiency, among others).

The seminar concluded by citing the following factors necessary for optimisation of public lighting:

• High quality research
• New standards and metrology
• Technological development
• Legislation
• Incentives
• Training
• Market knowledge
• Social knowledge