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Project Launch: 06/01/2017
Residential
Complete

Partner: Google Nest Labs

This pilot involving over one hundred thousand customers verified the energy savings potential of a smart thermostat schedule optimization program.

Overview

This pilot was conducted in two phases across 2017 and 2018. The Seasonal Savings offering allows customers with Nest Learning Thermostats to opt-in to a service that makes small adjustments to thermostat setpoints over a three-week tune-up period, while maintaining customer comfort. On average, scheduled setpoints are adjusted up by 1.5°F during the cooling season, with the biggest temperature adjustments taking place when customers are typically away from home. The pilot was implemented using a randomized encouragement design, in which all customers in the ComEd® service territory with a Nest thermostat were randomly assigned into a treatment or a control group. Treatment group participants opted in using a prompt shown on their thermostat.

Results

The first pilot found an average savings per treated thermostat of 71.7 kWh or 4.5 percent of cooling load from late June/mid-July through October 14, 2017; and 38.8 kWh or 2.5 percent of daily heating load for the 2017/18 heating season. The number of opt-in participants as compared to all qualifying devices was 53,334, meaning 62 percent of eligible devices opted in.

Navigant’s evaluation found it was successful in testing the technical feasibility of thermostat optimization and in customer acceptance of the offering. However, important questions remained regarding incremental savings from future deployments, persistence of savings, and expected savings from a full-season deployment. The second season of pilot participation was aimed at determining measure persistence or whether there may be increased savings, as ComEd had recently transitioned to CPAS goals. That impact evaluation found some interesting multi-year effects and evidence that could support a two-year measure life, but due to the short overall measure life, the Emerging Technologies Team has not yet developed this service into a larger-scale offering.

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