How much energy efficient light bulb use per day?
First off, we need to get some definitions out of the way. The amount of energy being used per second of time is called wattage. In order to compute total energy used, energy companies usually multiply the amount of kilowatts (1000 watts) and the number of hours used to form kilowatt-hours. 1 kilowatt-hour is approximately 3.6 megajoules of energy. A standard incandescent light bulb uses around 60watts of energy. Assuming you leave a single bulb on for, say, 12 hours a day, the bulb will use (60 watts) * (12 hours) = 720 watthours or 0.72 kWhours, which is about 2,59 Megajoules. On the other hand, a fluorescent light bulb (the curly energy-efficient ones) will use around 13 watts to supply the same amount of light. (13 watts) * (12 hours) = 156 watthours or 0.156 kWhours, or 0.56 Megajoules for the same amount of time.
