As the afternoon sun hit photovoltaic panels overhead, Gov. David Ige stepped into the refreshing interior of Building M at Nanakuli High and Intermediate School and the 1,000th classroom in his campaign to cool the schools.

“We had committed to air-conditioning and cooling a thousand classrooms, and today this is the 1,000th classroom, here at Nanakuli,” he said Thursday. “It took tremendous effort.”

The classrooms are in 88 schools across the state, all on the priority list for heat abatement. Another 300 classrooms will have AC installed by the end of September with the $100 million appropriated for the project by the Legislature.

The campaign entailed far more than simply plugging air conditioners into windows. The electrical grid at most campuses couldn’t handle that, upgrades are costly and traditional AC units would further inflate utility bills.

Instead, the Department of Education opted for sun-powered air-conditioning systems for the vast majority of the classrooms, according to Dann Carlson, assistant superintendent for school facilities.

Nanakuli senior class president Talafaaiva Ealim said students are happy with the change in classroom climate.

“I can tell you, it’s made a huge impact here at Nanakuli High and Intermediate School,” he said. “The learning environment is way, much more comfortable.”

“Before, we would work in the heat, and we’d get all sweaty and sticky,” he said. “It’s a whole lot easier for the teachers to teach now that students are paying more attention.”

At Building M, which is typical of the AC installations, rooftop photovoltaic panels charge batteries that are mounted on the back wall. Those batteries provide a steady source of electricity for the split air-conditioning system. Quiet overhead fans help distribute the cool air.

“We were tasked with the challenge of supporting these air-conditioning units without adding any load to the schools, because we already know that they are already taxed as they are, and to upgrade any of the schools would have been very expensive, very time-consuming,” said Billy Ornellas, electrical engineer with Ronald Ho &Associates, who worked on the classroom at Nanakuli.

“The (photovoltaic) system creates enough energy to run the AC system throughout the day, as long as there’s sun, and the batteries provide a backup for cloudy, rainy periods and you get some nighttime use,” he added.

The department spread the funds across as many campuses as possible on its priority list for heat abatement. The 88 campuses with the newly installed air conditioning are on Oahu, Hawaii, Maui, Kauai and Molokai.

Of the roughly 11,000 public school classrooms across the state, about 5,000 of them now have AC, according to Carlson.

The governor had announced his plan in his State of the State address in January 2016 with an end-of-year deadline. But contractor bids came in way over budget, and the deadline was extended.

Ige thanked the Legislature for funding the campaign and the students for providing the inspiration. Students and teachers had staged rallies at the Legislature for years to raise awareness of their plight, with some classroom temperatures reaching as high as 100 degrees.

Ten general contractors were involved in the statewide effort: CC Engineering &Construction, HBM Acquisitions, Elite Pacific Construction, F&H Construction, Arita-Pulson General Contracting, Shioi Construction, MJ Construction, A’s Mechanical and Builders, Nan Inc. and OpTerra.

More information on the DOE heat abatement program is available online at bit.ly/1VJjTr6.