Space heating consumes the most energy, 38% of the total used. Water heating uses 8% of the total, cooling and ventilation consume 7% each, while refrigeration uses another 6%.
Lighting was the second biggest energy consumer at 20%. Office equipment, personal computers, cooking and miscellaneous uses accounted for the balance, some 16%.
The Commercial Buildings Energy Consumption Survey (CBECS) collected information on buildings greater than 1,000 sq. ft. with more than 50% of their floor space devoted to commercial activity. The most recent survey, 2003, is the eighth in a series begun in 1979.
The 2003 CBECS found that:
There were more than 4.9 million commercial buildings in the U.S.
They comprised more than 71.6 billion square feet of floor space.
They consumed more than 6,500 trillion Btu's of energy.
Electricity was the primary form of energy used55%. Natural gas was second, at 32%. District heat accounted for 10% and fuel oil just 3%.