Large Office Buildings

Managing Energy Costs in Office Buildings

Large office buildings (those more than 100,000 square feet) in the US use an average of 20 kilowatt-hours (kWh) of electricity and 24 cubic feet of natural gas per square foot annually. In a typical office building, lighting, heating, and cooling represent almost 70% of total energy use (Figure 1), making those systems the best targets for energy savings. Energy represents about 19% of total expenditures for the typical office building, which is a significant operational cost deserving of management attention.

Average energy use data

Figure 1: Energy consumption by end use
Nationally, ventilation, cooling, and computers are the major electricity consumers in large office buildings; space heating dominates natural gas consumption.
Pie chart showing electricity end uses: Ventilation, 26%; Miscellaneous, 24%; Cooling, 17%; Computer, 17%; and Lighting, 16%.
Pie chart showing natural gas end uses: Heating, 80%; Cooking, 7%; Water heating, 7%; and Miscellaneous, 6%.
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To better manage your building’s energy costs, it helps to understand how you are charged for those costs. Most utilities charge commercial buildings for their natural gas based on the amount of energy delivered. Electricity, on the other hand, can be charged based on two measures: consumption and demand (Figure 2).

Figure 2: Load profile for a typical California office building
Hourly energy consumption data show that lighting and cooling present the largest opportunities for reducing peak demand charges in office buildings.
Figure 2: Load profile for a typical California office building
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