Moving into the mainstream

Solid state lighting (or LEDs) is already being seen as the future of lighting; its potential for CO2 reduction is drawing the attention of designers and Governments across the world. But are LEDs matching these expectations? The progress from widespread use in theatrical and architectural lighting since the turn of the century has been truly dramatic and today LEDs are serious contenders in main stream interior lighting.

The first real successes for LEDs relied on their extraordinary ability to deliver lighting with great precision; close up, no spill, floodlighting can be achieved with much less power even though some conventional HID sources are more efficient in terms of lumens per Watt. This focussed ability has developed into much wider applications wherever directional, or spot, lighting is required thus taking LEDs into the interior of shops and display cases. Another unique benefit of LED lighting lies in its capacity to work even better in very cold environments; freezer display cabinets have been relit with LEDs to generate electricity savings up to 75% when compared to the previous fluorescent solutions.

The latest milestone to be achieved by LEDs is to successfully compete with both halogen and compact fluorescent downlighters. A timely development when considering the arrival in October 2010 of the more stringent regulations set down in the latest version of Approved Documents L2A and L2B. The new efficacy requirements will be difficult for many current CFL downlighters; the arrival of LED equivalents that have system efficacies (luminaire lumens per Watt) in excess of 60 means that these ubiquitous luminaires can still be included in work place interiors.

Although the best LEDs cannot yet match the efficacy of the leading T5 fluorescent luminaire technology they are getting much closer. So much so that there are now all LED solutions being adopted in retail and office applications. In the former area the choice of colour temperatures (and even solid colours) together with the absence of forward UV and IR radiation is increasingly attractive to the smart retailer. In the workplace the potential to design more exciting luminaires that are not constrained by the need to accommodate comparatively large glass tubes is now attracting interest. Maybe we will have to stick with square or rectangular tiles in false ceilings but LED luminaires can provide the interior/lighting designer with much greater freedom.

One new luminaire concept using LEDs creates concentric circular light engines that can be operated and dimmed separately. The control possibilities offered by such a luminaire might be exploited both in terms of a dynamic, variable colour temperature, environment and as a truly energy efficient lighting scheme. The overall installed load of such an LED solution might be slightly higher than a best practice fluorescent but the benefit to the user could well be fewer kilowatt hours consumed. Functional control strategies made possible with LEDs include greater precision in delivering light where it is needed as well as faster reactions to sensors and occupancy. And LED life will not be compromised in any way no matter how much they are dimmed and/or switched. In fact both functions will extend their installed life.

Philips Lighting has been involved with pioneering work in the development of dynamic fluorescent lighting in a variety of work environments. This work pursues the thought that we need to consider the health and wellbeing of the occupants as a prime lighting design consideration. The introduction of LEDs will potentially build on the knowledge gained so far and permit the development of even better workplace lighting. There is no doubt that LEDs are the most exciting innovation that the lighting industry has encountered for many years; the challenge is to deliver this technology to meet the aspirations and expectations of the users. It is therefore essential that new standards are developed for LEDs and their associated electronics and luminaires are developed and adopted so that the designer, installer and ultimate user can rely on robust and consistent product descriptions. Photometry, colour temperatures, colour rendering indexes and actual performance need to be expressed according to set standards to avoid user disappointment.

As can be seen above, LEDs are here to stay and already making inroads into main stream applications. Whereas today they make up no more than 10% of the lighting market, Rudy Provoost, CEO Philips Lighting, confidently expects solid state LED products to achieve 50% market penetration by 2015 and over 75% by the end of the decade. These are truly exciting lighting times we live in today.