This paper from Lawrence Berkeley National Laboratory explores the potential of demand response strategies to reduce peak electricity demand from commercial buildings. These buildings account for 45% of the summer peak demand, which is estimated at 330GW nationally. Demand response may include limiting total usage (the demand) and load curtailment. These actions are motivated by time-of-use electricity rates, real time rates, or event notifications. A trial was described that achieved an average of 8% demand shedding with a peak of 56%. Demand response will not be a major driver for new building control systems but should be accommodated.