The start of a new school year is proceeding as usual in Hawaii public schools, with backpack- toting students filing into classrooms — thousands of whom will be uncomfortably hot for many days before next summer’s break. The absence of air conditioning is not a new problem, unfortunately.

Eleven years ago, when fewer than two dozen public schools were fully air-conditioned, many teachers resorted to oscillating fans or handing out wet paper towels to keep students cool and focused. And hundreds of students from Campbell High, situated in the sun-baked Ewa Plain, marched at the state Capitol, drawing much-needed attention to the matter.

Since then, Hawaii has made some strides. About 6,200 of the state Department of Education’s 11,000 classrooms now have AC. Still, the road to this juncture has been shamefully long for a state that prides itself on caring for keiki by equipping them — largely through educational opportunities — to take on the future in the islands.

Hawaii State Teachers Association President Corey Rosenlee was a social studies teacher at Campbell High at the time of the 2008 student march. In an HSTA video released last week, he recalled that for years his classroom temperature would hit 90 degrees, and had spiked to the triple-digit mark.

“I saw the impact of those hot classrooms on my students. By fourth period, they had been so hot for so long that students couldn’t concentrate on lessons and ended up sometimes just putting their heads down,” he said.

Numerous studies link the quality of school facilities to student achievement, and some researchers say failing to maintain a comfortable classroom temperature contributes to an achievement gap.

That’s easy to believe. Few of us can remain focused on any set of tasks for hours on end in a too-warm room. Clearly, that’s why Hawaii’s businesses and bureaucrats alike work in air-conditioned spaces whenever possible.

One stride in addressing the classroom problem was initiated in 2016, when the Legislature, pressed by the governor, made a $100 million emergency appropriation for heat abatement and energy efficiency.

Altogether, 1,300 classrooms across the state got AC through that action. But installation was hugely expensive — up to $100,000 for a classroom, said HSTA — because due to maxed-out electrical capacity on campuses, the DOE opted for green-focused but pricey solar power.

It’s encouraging that in the last few years, the cost for adding AC has dropped dramatically due to a freeing up of capacity to handle electrical load — achieved by energy-efficiency moves such as replacement of fluorescent lights with LED lights in all Oahu schools and in more than half of neighbor island schools.

That’s setting the stage for another stride, one that Rosenlee views as a “game-changer” as it holds potential to bring AC to thousands more classrooms. The bump in electrical capacity is making it possible to install relatively inexpensive window units. The cost estimate for a typical 900 square-foot classroom is well below $10,000.

Through the new School Directed AC program, the DOE provides an assessment of a school’s capacity to handle units and recommends options. It’s then up to the school to foot the bill through donation, fundraising or its own budget — and connect with a licensed installer.

With more than 4,500 classrooms still without AC, scores of schools are signing up for the program. But they should not have to shoulder the burden alone. Establishing a classroom environment that’s conducive to learning should not hang on proceeds from bake sales and the like.

Three years ago, Gov. David Ige and state lawmakers rightly supported funding to reach the halfway mark. Now they should allocate funds to reach the end of this sweaty road to air conditioning in all classrooms.