A Comparative Candlepower Distribution Analysis for Compact Fluorescent Table Lamp Systems

The residential lighting sector represents a significant opportunity for energy conservation due to the almost exclusive use of inefficient incandescent sources. Compact fluorescent lamps (CFLs) have the potential to transform this market by using one fourth as much power as an incandescent to provide the same amount of light. While technical advances such as triphosphors and electronic ballasts have addressed issues of color rendition, flicker, and hum, CFLs still face significant market barriers, particularly their perceived brightness level in traditional fixture applications. When operated in fixtures originally designed for A-lamps, CFLs with equal total lumen packages can appear dimmer due to differences in their light distributions. One such fixture, the common table lamp, is typically operated for more than 3 hours a day, and thus represents a significant opportunity for energy savings. LBL conducted a series of goniophotometric candela distribution studies of table lamps with the initial objective of matching with CFLs the light distribution of the consumer accepted A-lamp. While goniometric testing was done on numerous CFL and incandescent sources, this paper focuses on three typical sources which have very different distributions. Our photometric studies indicate that horizontally oriented CFLs may produce a more desirable distribution than either A-lamps or vertically oriented CFLs by minimizing shade losses and thus maximizing the amount of useful light leaving the fixture. Optimizing fixture geometry and lamp position can significantly increase the efficiency of these CFL fixtures. Ongoing research with the fixture industry seeks to identify and develop efficient source/fixture configurations.