Mansfield electric commission prorates Nest thermostat rebate, creates geothermal rebate

The Municipal Electric Commission on Nov. 20 voted to prorate its Connected Homes monthly rebate for customers using Google Nest thermostats and approved a new rebate for ground-source (geothermal) heat-pump systems.

General Manager Joe briefed commissioners that the program currently counts 152 programmable thermostats in the town program, 141 of which are Google Nest devices, and that vendor reporting does not identify individual customers' participation in peak-reduction events. "They can always override the thermostat," Joe said, explaining why Mansfield cannot verify individual Nest participation and recommending a prorated approach.

Under the approved change, the $5 monthly rebate will be prorated by the observed participation rate among Nest thermostats on an aggregate basis (option 2), effective Jan. 1, 2025. Commissioners discussed keeping the program unchanged or eliminating Nest rebates entirely; several said prorating is a fair compromise. A motion to adopt the prorated rebate passed 5–0.

The commission also approved adding a ground-source heat-pump rebate to the incentive program. Joe described residential geothermal installs as costly — "in the $20,000 to $30,000 range" — and proposed a rebate structured by capacity. The commission approved a motion to cap the rebate at $500 per ton with a maximum of 5 tons per residence (which would make the per-residence cap $2,500) and an annual program budget of $20,000; the motion passed 5–0.

Both votes were made at the commission meeting immediately before the Select Board session and are meant to align incentives with measurable system benefits while protecting ratepayers from subsidizing devices that do not contribute to peak reductions.