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The lights are on but nobody’s home
Eugene Water & Electric Board staff recently analyzed typical daily electric use from 15-minute meter data for 91 commercial buildings in Eugene. The average April weekday profiles for 17 office buildings and 20 retail buildings are shown in Figure 1.

The results are in and the after-hour electric use is surprisingly high. In fact, if the high-load is compared to the low-load, typical after-hour office use is in the range of 35-60 percent of the occupied value. Retail building load is typically 30-60 percent when empty.

That means a lot of electricity is being used at night when nobody is there, providing an opportunity for significant savings on electric costs. Strategies that can reduce unoccupied electric use include:

• turning all lights off at night except for limited security lighting.
  
• coordinating custodial work so only the area being cleaned is lit.
• turning off computers when leaving for the day, or have information services install automated power management software on your network.
• making sure programmable thermostats are set properly to set back temperatures at night.

For more ideas on saving energy in your building, check out the Energy Smart Operations booklet online at www.eweb.org. If you want to subscribe to on-line energy profiling data for your building, call us about our “Powerline” service. The full study as presented at ACEEE in August 2004 is also available on-line.