The nation is spending $46 billion less each year on school construction and maintenance than is necessary to ensure safe and healthy facilities, according to estimates in a new report.

The study, released by a group that advocates for environmentally-sound buildings, is meant to draw attention to the condition of buildings that on weekdays house some 56 million students and teachers — more than one-sixth of the U.S. population — but that nevertheless attract little attention in the national debate over education policy and reform.

“We are consistently and persistently underinvesting in our nation’s schools,” said Rachel Gutter of the D.C.-based Center for Green Schools at the U.S. Green Building Council, which co-authored the report. “Communities want to resolve these issues, but in many cases the funds simply aren’t there.”

Detroit has made headlines this year for crumbling schools plagued by rats, roaches and mold. But while conditions in the Motor City are particularly deplorable, the average U.S. school is more than 40 years old, and thousands of school buildings nationwide are in need of upgrades, according to the federal government.

Poor communities in far-flung rural places and declining industrial city centers tend to be in a particularly bad situation: School construction budgets rely even more heavily on local dollars than operating budgets. And in many places spending has not recovered from cuts made during the recession, leaving school districts struggling to patch problems.

In Philadelphia, which has suffered deep budget cuts in recent years, an elementary school was forced to delay its opening last fall after a worker discovered that the building’s foundation was structurally unsound. A boiler exploded at another of the city’s elementary schools in January, seriously injuring an employee.

“These things are happening because too many public officials have turned a blind eye to what’s really going on in schools across Pennsylvania,” Pennsylvania Sen. Vincent Hughes (D) said in a statement, calling on the state legislature to increase its investment in public education. “This is a fool’s errand.”

The federal government contributes about 10 percent to operating budgets but virtually nothing to school construction or renovation. Some states, such as Wyoming and New Mexico, have strong statewide programs for school construction, but a dozen states offer no assistance, which means the cost of school construction falls entirely on local taxpayers.

Among the states that do not contribute to school construction is Michigan, where Detroit has struggled so mightily to maintain healthy and safe buildings. Others are Wisconsin, Indiana, Oregon and Nevada.

“It’s entirely tied to the wealth of the district,” said Mary Filardo, executive director of the 21st Century Schools Fund, a D.C.-based nonprofit and report co-author. “It’s got inequity built into it.”

Filardo said that there is a growing body of research that shows links between the school environment and a child’s ability to learn, and yet the condition of school buildings remains little-mentioned in discussions about closing achievement gaps.

She suggested that the federal government could help push for equitable school facilities by providing funding for construction in high-poverty schools, as it now does for teaching and learning through the Title I program. But that would be politically difficult given the GOP-led Congress and its push to shrink federal spending, she acknowledged.

The last time the federal government attempted to survey the condition of the nation’s school buildings was in 1995. At the time, more than 8 million students attended 15,000 schools with poor air quality; 12 million students attended 21,000 schools in need of new roofs or roof upgrades; 12 millions students attended 23,000 schools with inadequate plumbing.

And the list goes on: The Government Accountability Office estimated that it would cost about $112 billion to ensure that all schools were in good condition.

In the two decades since the GAO made that estimate, the nation has spent an average of $99 billion a year on maintenance, operations and construction, according to the new study.

And that’s far less than the $145 billion that’s needed, according to the study, which suggested a standard — a tweaked version of commercial-building standards — that should be used to estimate the cost of maintaining the nation’s school facilities.

The report calls not only for greater public investment in school facilities, but also for an effort to collect and share more information about the condition of school buildings — which account for the second-highest level of public infrastructure spending, after highways.

There is no comprehensive federal data source on school buildings, and the quality and amount of information varies widely at the state level. The inconsistency and scarcity of data on schools has contributed to their neglect, Gutter said: “This is a problem that we’ve just made it so easy for ourselves to ignore.”