The light-emitting diode (LED) is a rapidly evolving, energy-efficient light source technology that holds promise to address the increasing need for energy conservation. However, the common belief that a high-efficacy light source equates to lower energy demand in application is incorrect. Generally, when a new light source technology replaces an existing light source in an application and claims energy savings, the inherent assumption is that all of the requirements of the application are met. In the case of directional lighting applications, what matters ultimately is the amount of luminous flux illuminating the task area. Therefore, when quantifying the performance of a luminaire, ideally one must consider only the amount of flux reaching the task area and the total power demanded. The objective of this paper is to introduce an alternative concept, application efficacy. This paper will demonstrate the concept's usefulness and proposed metrics for three different lighting applications-under-cabinet task lighting, refrigerated display case lighting, and outdoor parking lot lighting-and show how it better relates to energy demand. Details of laboratory experiments and software analysis along with data are presented for the three applications.

Date Published: 23 August 2010
PDF: 7 pages
Proc. SPIE 7784, Tenth International Conference on Solid State Lighting, 77840L (23 August 2010); doi: 10.1117/12.863212

Published in SPIE Proceedings Vol. 7784:
Tenth International Conference on Solid State Lighting
Ian Ferguson; Matthew H. Kane; Nadarajah Narendran; Tsunemasa Taguchi, Editor(s)