Lumens are a unit of measurement used to define the amount of light output by a given light source. 100-watt halogen light bulbs produce 1,800 lumens, or 18 lumens per watt of power drawn. 100-watt incandescent light bulbs generally produce around 1,750 lumens, or 17.5 lumens per watt of power used.
Neither halogen light bulbs nor incandescent light bulbs are efficient for the amount of power drawn to produce light. The California Energy Commission claims that halogen light bulbs are slightly more efficient than incandescent light bulbs, using 20 percent less power than incandescent light bulbs of the same wattage.
One of the reasons that both halogen light bulbs and incandescent light bulbs are not efficient and consume great amounts of power is that they operate at very high temperatures. A lot of the power they consume goes into the production of heat instead of light.
According to The Great Internet Light Bulb Book, reducing the amount of power drawn in by halogen light bulbs and incandescent light bulbs can lower the operating temperature of the light bulb's filament. When a filament operates at lower-than-normal temperatures it lasts longer, and the light bulb will last longer.
According to data collected by the U.S. Naval Observatory Flagstaff Station, 100-watt halogen and incandescent light bulbs will both cost the consumer around $40 per year to operate. This figure is assuming 4,000 hours of operation at 10 cents per kilowatt hour of power consumed. Since halogen light bulbs last longer than incandescent light bulbs, they will not need to be replaced as frequently throughout the year.