Smart Thermostat Study
The purpose of the Study is to understand the effect of this emerging technology in residential homes within certain hot and cold climate zones in PG&E’s service territory. The two focus areas for the study are an estimation of the energy savings for participating households, and an assessment of the participants’ experience while taking part in the study. The Study used a randomized encouragement design (RED) approach in which several thousand homes were randomly assigned to the encouraged group, all of whom were offered a free, directly-installed smart thermostat, and two thousand similar homes were randomly assigned to a control group, none of whom were offered a thermostat. Three different brands of thermostats were tested in the study; the goal was to install 1,000 of each type of thermostat in participants’ homes. A total of 2,207 thermostats were installed.
Monitoring occured over two winter heating and two summer cooling seasons, from late 2015 through the summer of 2017. A report detailing the first year's findings was posted in December 2016. During the first year, all three thermostats achieved annual electric savings ranging from 4-5%. One of the thermostats tested also achieved annual gas savings.
The second year's analysis indicates that savings persisted in the second year, although at a somewhat lower level. The lower level of savings is due in part to the extreme heat in the second year of the study. Also continuing the study for a second year led to sample attrition making the savings more difficult to detect. The M&V consultant's interpretation of the data and the results lead them to conclude that customers are likely to save electricity with the Smart Thermostat technology alone, even without any programmatic interventions or customer education efforts.