Over the past decade, the state has installed air conditioning in just three schools.

Three more projects are under way, but the Department of Education has acknowledged that without a lot more money — and electricity — it can’t air-condition many of the state’s hottest public schools any time soon. So it’s now studying cheaper alternatives to bring temperatures down, like ceiling fans, better insulation and new roofing .

When those measures were taken for four portable classrooms at Kahuku High and Intermediate recently, the highest temperature recorded — shortly after lunch — came down to 85 degrees from a brain-boiling 103 degrees. Still hot, but at least bearable.

Department of Education officials are also trying to determine whether there’s a better way to prioritize air-conditioning projects that would pinpoint the hottest classrooms, rather than prioritizing based on the average temperature of a school.

"In the ideal, we would attack the worst spaces first, not necessarily the whole school," said Randy Moore, assistant superintendent of the office of school facilities and support services. "Comfort on any given campus varies widely, building to building, even room to room. We acknowledge the serious challenge."

In the meantime, students in public schools around the state continue to learn in classrooms that can be downright intolerable, especially on humid days. And the prospect of getting a big chunk of money for air conditioning this year is slim to none, with the state Legislature eyeing a budget shortfall and weighing other priorities.

Today, 29 (or 11 percent) of the state’s 258 public schools have central air conditioning. New schools come with it, as do new buildings built on old campuses.

Putting air conditioning in old schools is pricey, ranging from $3 million to $10 million, depending on the size of the school and the electrical infrastructure upgrades needed.

And the cost of air conditioning doesn’t end with installation.

"They’re really expensive to operate," Moore said.

THE PROBLEM of how to make schools more comfortable for modern kids — many accustomed to air conditioning — has been around for years, but the situation has gotten more acute in some overcrowded schools as class sizes have grown.

Corey Rosenlee, a social studies teacher at Campbell High School in Ewa Beach, said fans are next to gold in his packed classroom on hot days. And hot days are frequent: He estimated three-fourths of the school year is uncomfortably warm.

On those days — once 30-plus teenagers pack in — temperatures in his classroom easily reach 100 degrees. Rosenlee polices fans to make sure every student is getting a little fresh air (and nobody is commandeering them). He also turns off the lights to try to cool things down. With no lights, he said, the kids find it a little hard to read.

"One hundred degrees is not a classroom," Rosenlee said.

Three years ago, Campbell students went to the state Capitol to rally for air conditioning. Legislators sympathized, but a tough budget situation meant no money went to the project that fiscal year. If the department adheres to its priority list for air-conditioning installation, two more campuses — Ewa Beach Elementary and Ilima Intermediate — should get air conditioning before Campbell.

Pohakea Elementary School in Ewa Beach is one of three schools where air-conditioning projects are under way. By next school year, air conditioning will be installed in two classroom buildings. The last building will be finished in the fall of 2012.

Principal Stacie Kunihisa described the temperature in classrooms this way: " hot."

She added, "Unbearable."

Pohakea teachers have put fans in their classrooms — and are often seeking donations for more — leave their doors open for ventilation and let kids bring in water bottles from home. Children don’t even get relief in computer labs, where they take annual tests to determine whether they’re proficient in math and reading.

Only one of the school’s three labs is air-conditioned.

"We don’t have enough electricity to air-condition all three," Kunihisa said.

The DOE acknowledges that hot classrooms are a problem. And recently — recognizing the snail’s pace of installing air conditioning and given limited funding — the department launched three pilot projects to study what relatively small steps can be taken on campuses to reduce classroom temperatures.

» At Kahuku Intermediate and High School last year, the DOE spent $311,000 to install different heat-reduction modifications — things like solar "light tubes" so lights could be turned off, new roofing, paint and even walls to reflect heat (not take it in), ceiling fans and insulation. Monitoring for the pilot is set to run through April.

Charles Kaneshiro, principal of architecture firm Group 70, which oversaw the project, said the portables that weren’t part of the pilot had a temperature range from 68 to 103 degrees. In the improved portables, temps ranged from 72 to 85 degrees.

The next step is to figure out what modification worked best, Kaneshiro said.

» At Ewa Beach Elementary, crews installed ceiling fans in traditional classroom buildings and re-roofed to improve insulation. The $233,000 project last year didn’t involve any monitoring to record temperatures before and after, but teachers and students said the small improvements made things a lot more comfortable.

» As early as this school year, ceiling fans will be installed in 227 classrooms in schools on the Leeward Coast. The project is set to go out to bid in March.

Duane Kashiwai, DOE public works administrator, said the three projects are appealing because they’re less costly and more earth-friendly than air conditioning.

"The bottom line is we’re looking at ways for more passive cooling," he said.

Legislators say they are concerned about air conditioning in schools, but say the situation is a difficult one: There’s not enough money to retrofit every campus. Even if there were, electrical capacity is insufficient to power new air-conditioning systems.

State Sen. Will Espero, (D, Ewa-Honouliuli-Ewa Beach), said air conditioning "should have been a higher priority for the state. We haven’t made it a priority." But Espero added there are plenty of other needs, and lots of competing funding requests.

For several years, including this session, lawmakers have considered a measure mandating that the DOE follow a schedule for installing air conditioning and stick to it. The bill calls for all public schools in Hawaii to be air-conditioned by 2016.

Rep. K. Mark Takai (D, Newtown-Pearl City), a member of the House Education Committee and one of the legislators who introduced the measure, said air conditioning isn’t just about keeping things cool. Some schools, including Lehua Elementary, are located close to the highway, and teachers must compete with traffic noise.

He said the bill is meant to bring attention to an issue that isn’t going away.

The measure’s chances of passing this session, he said, are not good.