Design team presents all‑electric high school; energy use projected about half of existing building

An engineering and design team told the Bristol Warren Building Committee that the proposed new high school is designed as an all‑electric, high‑performance building and that modeling shows energy usage roughly half that of the existing high school.

"Our goal was an all electric building, and that is what we what we have here," said Mike Pew, electrical engineer with CMTA, during the committee's design update. He said the base mechanical approach uses air‑to‑water heat pumps feeding four‑pipe fan coils in classrooms, with a geothermal system included as a bid alternate.

The design team said they prioritized the building envelope, orientation and tight infiltration control before sizing equipment. They described steps taken to reduce mechanical loads, including lower‑flow kitchen exhaust through equipment selection and using electric alternatives to laboratory gas burners.

Why it matters: the committee is seeking to reduce long‑term operating costs, qualify for energy incentive programs and limit on‑site emissions. CMTA presented energy use intensity (EUI) comparisons that show the new high school's EUI falling from an estimated 62 for the existing building to about 25–27 with the geothermal alternate and roughly double that with only the air‑source heat pump. "It cuts that in half," Pew said of the air‑source design compared with the current high school.

The team said a life‑cycle cost analysis comparing gas, hybrid and all‑electric options found that the air‑source and geothermal alternatives produce substantially lower lifecycle costs over a 30‑year horizon. "Over the 30 year period, the air source and the geothermal come in significantly, like, 30 to 40% less on the life cycle cost," Pew said.

Design details disclosed to the committee include: - Primary HVAC: air‑to‑water heat pumps with four‑pipe fan‑coil units for classroom level control (base bid). - Add alternate: geothermal low‑temperature hot water system (bid alternate tested and deemed viable). - Domestic hot water: heat‑pump water heaters sized for efficiency. - Food service: equipment selections (combi ovens, different exhaust layout) reduced kitchen exhaust from an initial ~6,000 CFM to just under 3,000 CFM, lowering mechanical loads. - Science labs: electric burners considered to avoid on‑site gas service. - Renewables and EV readiness: rooftop renewables and six EV charging stations included with infrastructure sized for expansion consistent with the 2024 energy code.

CMTA said the project team will complete the energy model now that design is at the construction document stage and will monitor actual energy use for one to two years post‑occupancy to compare bills with modeled projections.

The committee discussed incentives and reimbursement tied to energy performance. Pew noted that reaching a low EUI helps access certain incentive programs.

No formal decision on the air‑source vs. geothermal selection was made during the meeting; the geothermal system is included as a bid alternate so the committee can compare bids and lifecycle costs before awarding contracts.

Ending: The design team said it will finish the energy model and return to the committee with final numbers; committee members asked follow‑up technical questions on particular systems and acknowledged the design's focus on lowering operating costs and emissions.