Improving the Performance of Integral Screw-Base Compact Fluorescent Lamps in a Base-Down Burning Position Using Thermal Bridge Systems

Many residential applications of the integral ballast, screw base compact fluorescent lamp (CFL) require a base-down orientation, as exemplified by table and floor lamps. Positioning CFLs base-down results in a 10-25% loss in lumen output, due to excess mercury vapor pressure in the lamp. These losses may limit consumers acceptance of these new CFLs as a viable retrofit strategy. To mitigate output losses, researchers are developing thermal bridge systems that cool the small tubulation of the lamp, thereby optimizing the mercury vapor pressure. Thermal bridge systems consist of small copper heat sinks that fit entirely within the integral ballast compartment. Experimental data indicates most of the thermally based losses are recoverable, allowing for a lamp system that produces approximately the same lumen output regardless of orientation. As base-down positioning has wide residential application, the improved lumen output of these lamps would have a significant impact on residential retrofits.