Do CFLs Save Whole-House Energy?

November/December 2008
A version of this article appears in the November/December 2008 issue of Home Energy Magazine.
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November 06, 2008
If CFLs decrease cooling loads compared to incandescents, but increase heating loads, do they save energy overall?
Energy-efficient compact fluorescent lamps (CFLs) are becoming more and more widely available in the marketplace. Using these energy-efficient lamps in homes reduces electrical energy use and power demand. However, it also affects space-heating and space-cooling energy use. The take-back effect—the interaction of lighting with other loads—alters the overall cost savings associated with lighting. During the heating season, CFL lighting reduces internal gains compared to incandescents and therefore increases the heating load. During the cooling season, CFL lighting reduces the cooling load. Do these effects offset each other? Is the net effect of using CFLs in place of incandescents positive or negative? A number of field studies of commercial buildings show that replacing conventional lighting with energy-efficient lighting increases the heating load and reduces the cooling load. But residential use of lighting is a different story. In residential buildings, lighting is used selectively, depending on the occupants’ needs. To learn more about the net impact of CFL lighting in housing, Natural Resources Canada performed detailed field research on the effect of CFL lighting on a home’s overall energy use. We also sought to validate an internal-gains model associated with lighting energy use.   Average ...

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