We retrofitted the fixtures with larger globes to accept the longer compact fluorescent lamps, and reduced wattage from the nominal 40 W to 9 W, while increasing lumens to 575 per lamp. If we had wanted even more light in the halls of these buildings, a transparent or clear prismatic globe could have been used. Whether labor savings are considered or not, the cost of bulb replacement should be evaluated along with energy costs for a life cycle cost analysis of each retrofit measure. When replacing existing incandescents with CFLs, retrofitters must choose between separate tube and ballast combinations or self-contained units that have both components. Some one-piece units have casings that make them look more like traditional light bulbs, but their lenses reduce the light transmitted.
Reflectors can rescue some of the light lost in fixtures.
CFLs used to replace incandescents in recessed-can fixtures do not direct the light output optimally. If a CFL is held end-on close to a wall, the end of the tube will cast a shadow. A reflective collar can direct some of the light downward to more closely mimic the old illumination pattern. Prepackaged compact fluorescent floods and spots are also available with built-in reflectors. Ballasts typically last for 50,000 to 65,000 hours, while lamps need replacement at 10,000 hours.