An alternative calculation starts with the fact that commercial building lighting consumes in excess of 81.68 terawatts (1999 data) of electricity, according to the DOE. Thus commercial lighting alone consumes about four to five million barrels per day (equivalent) of petroleum, in line with the alternate rationale above to estimate U.S. lighting energy consumption. Even among developed countries there are large differences in patterns of light use. American cities emit three to five times more light to space per capita compared to German cities.