How can I calculate the CO2 saved when using a compact fluorescent light (CFL) bulb?
One CFL uses 1/4 the electricity of a regular incandescent bulb. So, with a 100-watt light bulb you are saving 75 watts. If this bulb is on 8 hours a day (3.5 hours in the morning and 4.5 hours at night), the energy saved each year by using it is 75 watts x 8 hours x 365 days = 219,000 watt-hours or 219 kWh. This number equates to 143 lbs. of CO2 per year in California, or 11.9 lbs. of CO2 per month in California. Your calculations will vary depending on how many hours a day your CFL is on, the wattage of the bulb, and what state you live in. Note: the amount of CO2 generated per kWh in California is about 1/4 the national average, since California uses less fossil fuel (primarily coal) and more non-carbon based sources (hydro and nuclear) to make electricity – so choosing a different state could make a big difference.
