New Approaches to Residential Direct Load Control in California

New direct load control programs are being rolled out by utilities across the country. Traditional one-way, single-mode switch technologies are being replaced by remotely adjustable thermostats and adaptive switch technologies that learn how customers’ air conditioners actually operate over time and then optimize load impacts during events. Adaptive switches are designed to reduce air conditioner duty cycle by a percent of what the duty cycle would have been in the absence of the control event. Ramping strategies for thermostats increase temperature set point in several increments over the control period. These control approaches are designed to improve a program’s demand reduction profile, while making control periods more comfortable for customers. To date, formal evaluation of these expected benefits has been minimal. The PG&E SmartACTM program offers a unique opportunity to explore these strategies within a single program in a single location. The SmartAC program began in spring 2007. It has a goal of obtaining 305 MW of load relief from about 400 thousand devices by 2011. Participation is expected to be 95% from residential customers and 5% from small commercial customers. Customers were given a choice of two control technologies: 1. Adaptive switches 2. Programmable Communicating Thermostats (PCTs) with ramping capability The impact evaluation of the Program’s first year takes advantage of a sample of 300 residences evenly split between the two control technologies. New analysis methods were developed to address the new twists on standard switch and thermostat technologies. Savings were evaluated for fifteen control events during the summer of 2007.