Toting handmade signs to "Cool Our School," nearly 500 students from Campbell High School in Ewa Beach converged on the state Capitol with their teachers and principal Thursday to rally for air conditioning in the public schools.

"It gets like 90 degrees in the classroom," said Precious Guieb, a petite 11th-grader wearing heart-shaped sunglasses. "It makes you feel like fainting or falling asleep."

Campbell is fourth on the priority list of schools pegged to receive air conditioning, but there is no saying when that will happen. Through the past seven years, four campuses statewide have been air-conditioned and moved off that list.

The rally is part of a years-long effort to encourage legislators to step up the pace in funding such efforts. It was a field trip for the students, who are measuring temperatures in their classrooms, analyzing the data and writing or calling their legislators.

Organizers hope to get the issue on the radar before the legislative session starts in January. Students at 23 other schools have joined the campaign by sending letters to lawmakers, according to Corey Rosenlee, a social studies teacher at Campbell who organized the rally.

Statewide, 12 schools have central air conditioning, out of a total 255 campuses. A 13th campus, Loke­lani Intermediate, is midway through its conversion. The department has also been trying to make classrooms more comfortable by putting in ceiling fans and installing solar-powered ventilators, which pull hot air up and out of rooms, allowing cooler air to come in through windows.

"I empathize with everybody who has to sit in a hot classroom," said Ray L’Heu­reux, assistant superintendent in charge of school facilities and support services. "We’ve got to get that turned around."

"Whether that’s heat abatement or adding air conditioning, we’ve got a priority list looking at the schools most in need, and we’re working our way through them. At the end of the day, it comes down to resources."

Hawaii’s schools are old — on average 65 years old — and many could not handle the electrical load for air conditioning without structural upgrades. At Campbell, for example, the department estimates it would cost $13 million to put in central air conditioning campuswide. That includes electrical work, replacing jalousie windows with airtight windows, and the air conditioning, according to Duane Kashi­wai, public works administrator.

A similar air-conditioning project at nearby Poha­kea Elementary, which was put out to bid, was recently completed at a cost of $4.3 million, Kashi­wai said. Poha­kea has 38 classrooms while Campbell has 139, plus all the facilities that come with a high school.

Rep. Bob McDermott and Sen. Will Espero, who represent Ewa Beach, spoke at the rally, telling the students they would push the issue with their colleagues.

"I live in Ewa. My daughter goes to Campbell," McDermott told the students. "I have a personal stake in it. We’re working very hard. Your voices are important."

Campbell junior Amanda Thirion has lived in Okla­homa, California and Louisiana, and told the crowd that all her previous schools had air conditioning. She said she was appalled to find that most of Campbell’s classrooms have none.

"Never have I seen this lack of concern about the student environment," she said. "It isn’t a coincidence that my hottest class is also my lowest grade."

Francesca DePasquale, a science teacher at Campbell, has had her students taking the temperature in various classrooms at different times and also measuring humidity, then analyzing the data.

"It’s generally in the high 80s, sometimes 90s," she said. "It’s so difficult to function or concentrate or even stay awake. It’s been a really hot August and September."

Since 2011 the department has been installing ceiling fans in classrooms at 15 schools along the Wai­anae Coast and on the southeastern flank of Hawaii island. Across the state, many schools have ceiling fans and some air-conditioning units, usually in libraries and band rooms.

In town, Kaiulani Elementary School has ceiling fans in classrooms, and last year added solar-powered ventilation to its cafeteria.

"It’s made a significant difference," said Principal Rodney Mori­wake. "The kids are in a much more comfortable environment that doesn’t tax our electrical bill."

Rosenlee, the rally organizer, said air-conditioning units could also run on solar power and need not be expensive.

The department already has ambitious plans to install solar power at all its campuses within the next five years, with no upfront cost. The vendor will put in photovoltaic panels and be paid for the electricity they generate at rates below what schools now pay.

"We are about ready to award that proposal," L’Heu­reux said. "That’s for the entire inventory of schools in the state."

The electrical bill to power the state’s public schools is $48 million a year, a cost that has been growing even as conservation efforts have reduced overall energy demand on its campuses. The department estimates that if all schools were air-conditioned, that bill would jump to $132 million a year, L’Heu­reux said.

Students at the rally realized the campaign for cooler classrooms could be a long one.

"I hope we get air con before I graduate," said Josh Agta­rap, a junior, pulling at the front of his Sabers Football T-shirt to cool off. "We’re doing this all for the people younger than us."