When school bells ring at Northeast High School next month, 3,600 students will be greeted by new windows, daylight-controlled lights and ventilation units that will pump fresh air into their classrooms.

The upgrades — intended to improve learning and save energy — are part of a $23 million project at three Philadelphia schools, financed by the Philadelphia School District and launched in partnership with the Philadelphia Energy Authority.

Superintendent William R. Hite Jr. said the renovations, which also took place at Strawberry Mansion and Saul high schools, will save the district an estimated $375,000 a year in energy costs.

As the district evaluated its vast capital needs a few years back, “it wasn’t enough to just patch up those issues and move on. We needed to make smart decisions that would hopefully result in significant cost savings,” Hite said during a news conference Monday at Northeast High School, where he was joined by Mayor Jim Kenney and City Council President Darrell L. Clarke, who also touted the renovations.

The district announced the project in 2017 with the partnership of the Philadelphia Energy Authority, a municipal agency created in 2010. District spokesperson Lee Whack said officials are working to have construction completed at all three schools by the start of school Sept. 3

Over the last two years, the authority has helped facilitate $100 million in public and private investment in energy projects that have created 1,000 jobs, said Emily Schapira, executive director of the authority. Among its projects is the Philadelphia Museum of Art, the city’s single largest energy-consuming building, which has cut its energy costs by 24 percent, Schapira said.

Through its Philadelphia Energy Campaign, the authority is calling for $1 billion in investment in energy projects over the next 10 years. Kenney called the campaign a “tool to help us build a robust clean-energy market” and meet the city’s goal of transitioning to “100 percent clean energy” and cutting carbon emissions by 80 percent by 2050.

“It is so important that we take action against climate change now,” Kenney said at the news conference — the first in a series of city “Solar Week” events.

Of the school upgrades, Kenney said students "now have brighter, healthier learning environments because of the crucial renovations made to their classrooms.”

Hite said the school district is working with the energy authority to expand the renovations to more schools. According to the Philadelphia Energy Authority, the district approved the expansion of the program for up to 20 schools.

“We feel like we have proven the concept now, and we plan to do quite a few more of these projects going forward,” he said.

The district is also working with the state Department of Education to start “the nation’s first solar program of study," Hite said. Details of the three-year program for career and technical education students will be announced Friday.