Changing light bulbs to LED

LED lamps are 7 times as efficient as old, incandescent (filament) lamps, 5 times as efficient as halogen lamps and 50% more efficient than flourescent lamps, if you replace one onld 60 Watt lamp with a 9 watt LED you save 51 Watt every hour, if you use the lamp 4 hour/day, you save.

You can get LED lamps that fit most existing fixtures, you just have the only cost is to buy the LED lamp, Typical price of a good LED lamp.