The new gymnasium at Dunbar High School looks out onto the old school building in the background in 2013. The light-filled building earned the highest energy-efficiency rating. (Michael S. Williamson/The Washington Post)

This year, the architects of the rebuilt Dunbar High School announced that the building was one of the greenest new schools in the world, equipped with a geothermal heating and cooling system aided by wells extending 460 feet below the athletic fields and enough solar panels to power all classroom lights for eight hours on a sunny day.

The D.C. public high school, after a $122 million reconstruction project, was awarded Leadership in Energy and Environmental Design (LEED) platinum certification, the highest distinction awarded by the U.S. Green Building Council, which reviews building energy efficiency.

As District schools have been modernized, many of them are getting greener. But as the overall cost and fiscal management of the school district’s modernization program has come under scrutiny, so too are its environmental features.

The D.C. auditor this month recommended that the city analyze the costs and benefits associated with its LEED certification. The recommendation came as part of a report that was highly critical of the city’s oversight of the school building program and the growing costs of the program.

A 2010 master facilities plan, designed as a planning document to guide funding decisions for school modernization, sets LEED silver certification as a minimum target for all projects. The auditor’s report found that most of the modernization projects reviewed — including seven out of eight high schools — exceed the silver certification “potentially driving costs beyond projections.”

“While adhering to District standards for environmental quality is commendable, cost-benefit questions arise when projects exceed those standards,” the report said.

During the review for LEED certification, buildings are assigned points according to such things as water efficiency, pollution controls, air quality and energy efficiency. LEED rates buildings from among four levels: certified, silver, gold or platinum.

Kenneth Diggs, a spokesman for the city’s Department of General Services, which oversees the school construction program, said the 2010 Healthy Schools Act set a higher bar for environmentally friendly features by amending the Green Building Act of 2006 “to encourage school construction to achieve LEED gold certification.” By pursuing gold certification, contractors are simply building to code, he said.

The District has been considered a national leader in green construction.

Some other Washington-area school systems have also made LEED certification a priority. Arlington County has renovated three high schools; two have gold certification and one — Wakefield High School — is under review but could be rated platinum, according to John Chadwick, Arlington’s assistant superintendent for facilities and operations. Loudoun County Public Schools, which has been building new schools to keep up with enrollment, does not participate in LEED certification but uses the standards as a reference.

Twelve D.C. public schools have gold certification and two have silver. Fifteen are in the process of being certified, and 44 are not eligible because their renovations did not include the entire building, Diggs said.

Two schools, including Dunbar, achieved the platinum designation. Diggs said the platinum certification did not require extra costs, though he did not have a breakdown of spending associated with the buildings’ energy-efficient features nor an analysis of projected cost savings.

He credited the solar panels at Dunbar for earning the extra points that propelled it into the platinum category. He said Constellation Energy, a Baltimore-based company, paid for the panels in exchange for using some of the power they generate.

McKinley Middle School achieved a platinum rating for its interior renovation in part, Diggs said, because of some incidental features, such as being close to public transportation.

D.C. Council member David Grosso (I-At Large), chairman of the education committee, said he supports the goal of energy efficiency, but he’s worried about the potential costs associated with the certification process.

Without close government oversight, contractors running the projects do not have any incentive to think about “the whole city” and cost savings, he said. “They want to get award after award,” he said.

Since 2007, the city has paid two D.C. contractors as part of a partnership to perform the day-to-day management of the school system’s construction projects.

In a letter responding to the auditor’s report, Jonathan Kayne, interim director of the Department of General Services, said that the renovated schools have garnered many awards for design excellence.