NASHUA — More than $7 million in work is being recommended at the city’s high schools to improve energy efficiency.

“The opportunities for energy savings are substantial,” Mike Davey of Energy Efficient Investments told a Board of Education committee this week.

EEI, an energy contracting company, was hired by the school district about six months ago to review the city’s schools and study ways to become more energy efficient.

“An energy performance contract allows the district to leverage energy savings from improvements and combine that with capital needs improvements in the district to create a project which is usually budget neutral,” said Davey.

Nashua High School North and Nashua High School South are the district’s two largest energy users. EEI has found numerous improvements that could be implemented to guarantee annual energy savings, including LED lighting, infrastructure upgrades on hot water heaters, transformer replacements and more.

“We identified $3.6 million worth of work at North and $3.8 million worth of work at South, which would reduce your annual energy savings by $224,000 a year (per school) — and you would be eligible for $400,000 in grants and rebates toward that work,” Davey told the school board’s finance committee.

The payback period would be about 14 years and six months, according to Davey. While there are different bond or lease financing options available, he proposed that the amount of annual energy savings would be equal to the annual bond payment.

He stressed that the financing numbers and cost savings are still preliminary.

The committee voted to recommend that EEI move forward with an official investment grade audit for both of the high schools to determine more definite cost estimates. The full Board of Education must still vote on that recommendation.

Davey explained that LED lighting is a key component for large energy projects, and it has a quick payback period.

“The lighting alone would save $130,000 per school (per year), and that is just in electric savings,” he said, adding there would also be maintenance cost savings associated with that as well.

Although the company reviewed the possibility of installing solar panels on the roofs at both high schools, Davey said that is not being recommended at this time since the roofs still have about seven years of life expectancy.

It is best to align solar projects with new roofing projects, he explained, adding there is the potential to place solar panels at Dr. Crisp Elementary School and Fairgrounds MIddle School since those roofs are new.

The attractive part of performance contracting is that the district can leverage its energy savings to purchase needed improvements, according to Davey.

Aside from new infrastructure projects, he is recommending that the district consider utilizing one high school during the summer months to save energy costs, and that the school being used would alternate each year. If energy improvements are approved, it is likely that the work would be done consecutively at the two schools.