The Trumbull Public School District has a dilemma.

Six of its 14 buildings have heating plants 50 or more years old. Four others are relatively new but not completely up to date. The cost to modernize them and bring down today’s $2.3-million annual bill for natural gas, electricity and water has been projected to exceed $6 million.

But Trumbull also has a solution: a program recommended to the Board of Education by Facilities Manager Mark Deming. He completed a similar program in Branford and has taken on the challenge of doing the same in Trumbull, which is a much larger district.

The program has three elements — performance contracting to update the six buildings with the old heating plants, retro-commissioning the four more modern schools, and fitting solar panels to all remaining buildings.

The $5-million performance contract program is structured so savings from one project are rolled into the next; together, savings will be sufficient to fund the entire conservation program without the need for bonding.

The first performance contracting project was completed at Hillcrest School last summer. The old boiler was replaced with modern HVAC (heating, ventilation and air conditioning) and building automation systems, and LED lighting was installed throughout the building.

The $1.3-million cost was borrowed at less than the town’s AA+ rate and its annual repayment of $105,000 will be covered by its energy savings.

The new systems eliminate the need to maintain large volumes of heated water and they control airflow to keep temperatures constant year-round.

The LEDs, Deming noted, are warrantied for five years, have an estimated life of up to 20 years, and include occupancy controls that turn lights on when people enter a space and off when they leave.

Jane Ryan, Tashua, Booth Hill, and Daniels Farm elementary schools and Madison Middle School will also be updated under similar performance contracts.

The four schools with building automation systems — Frenchtown Elementary School, Trumbull Early Childhood Education Center, the just-renovated Trumbull High School, and the AgriScience School — are eligible for retro-commissioning under the EnergizeCT program sponsored by United Illuminating. Together they will will require an investment of $339,000. UI is providing an upfront incentive of $115,000 and will finance $209,000 of the remainder at zero interest over four years.

The upgrades will provide savings of $35,000 in year one, $50,000 in years two and three, and $106,000 once the loan is repaid — and as energy costs rise, the savings increase.

All system upgrades will be made during summer 2016. When school starts in August, these four buildings will be among the most modern and energy-efficient public school buildings in the state.

Another cost-saving measure will be automating building schedules across the system so they are heated or cooled only as needed and when needed.

The third component will be the installation of photovoltaic arrays on the school roofs.  The Facilities Department last summer won an auction for 800 kW of Zero Emissions Renewable Energy Credits (ZERCs). The panels will be installed over the next year and will provide 10% of the district’s power at a cost well below that for purchased electricity.

These projects will go a long way toward both making the schools more comfortable year-round and meeting Board of Education member Jeff Donofrio’s objective of reducing operating costs.