Let's compare an incandescent bulb and a CFL with the same light output. A 60-watt bulb does not necessarily provide more illumination than a 15-watt bulb. Why? Because watts measure energy use while lumens measure light output. Lumen information appears on bulb packaging. For example, a 60-watt incandescent bulb produces about 800 lumens. You can replace this 60-watt incandescent bulb with a 15-watt CFL and get the same amount of lumens (light output), but the CFL will use 45 watts less energy (U.S. Department of Energy, n.d.).

Source: UF/IFAS Energy Efficient Homes: Fluorescent Lighting, Hyun-Jeong Lee, Kathleen C. Ruppert, and Wendell A. Porter, FCS3270, 2008

Additional Resources

UF IFAS Energy Efficient Homes: Fluorescent Lighting - http://edis.ifas.ufl.edu/FY1031  

Consortium for Energy Efficiency. (2007).  Residential lighting. Retrieved April, 18, 2008, from http://www.cee1.org/resrc/facts/rs-lt-fx.pdf  

ENERGY STAR®. (2008, April) Frequently asked questions: Information on compact fluorescent light bulbs (CFLs) and Mercury, April 2008. Retrieved May 5, 2008, from http://www.energystar.gov/ia/partners/promotions/change_light/downloads/Fact_Sheet_Mercury.pdf

ENERGY STAR®. (n.d.a). Compact fluorescent light bulbs. Retrieved April 16, 2008, from http://www.energystar.gov/index.cfm?c=cfls.pr_cfls