LED lifetime is based on 12 hours of use each day. Carbon offsets are based on the reduced energy consumption of the LED bulb over its lifetime. The number of kilowatt-hours saved is multiplied by the pounds of carbon dioxide produced per kilowatt-hour to get total pounds of CO2. This factor is different for each state because power sources are different; some states are more dependent on carbon-heavy sources such as coal, while others use a higher percentage of sources that don’t produce carbon such as hydroelectric or nuclear power. The US average is 1.34 lbs of carbon dioxide per kilowatt-hour, from the US Department of Energy.
For example: a typical LED 7×1 watt LED bulb replaces a 75 watt incandescent and lasts 50,000 hours. The savings of 68 watts times 50,000 hours equals 3,400 Kwh. At 1.34 lbs of carbon dioxide per Kwh the savings is 4,556 lbs of carbon dioxide that is averted from being released into the atmosphere.