BETHEL — About 35 people attended a public hearing Monday night on a proposed $2.5 million energy conservation and air quality project for the Telstar Middle/High School complex.

Jim Lucy and Bob Marcotte of the Westbrook branch of Honeywell Inc., which recently completed an energy audit of the schools, led a question-and-answer session, SAD 44 Superintendent David Murphy said.

Some people questioned whether construction of a new complex might be a better solution, but Murphy said a new school would cost between $20 million and $30 million. Also, he said, the district would likely be on the state’s school construction list “forever,” because the state lacks money.

The energy and air-quality project appears to be the best solution for updating the 40-plus-year-old building. The district has saved about $1.2 million in a capital reserve fund, and has received notice it qualifies for a no-interest $1.3 million federal grant for the project.

The current ventilation system exchanges air in only two classrooms. The rest must have windows opened to get fresh air, according to an informational sheet provided by the district.

Murphy said tentative plans are to borrow $1.3 million for 20 years, which would cost district residents about $65,000 a year.

“We can make up some of that,” Murphy said.

Much of that extra cost would be offset in five years when a major water and sewer project at the school is paid off.

Residents of the five district towns of Bethel, Greenwood, Andover, Newry and Woodstock will have the final say on the project when they go to the polls Nov. 6.

Although the Crescent Park Elementary School expansion project will be paid off next year, Murphy said the district won’t realize any savings because it will lose some state aid because its debt is paid.