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Experts Weigh In On Long Term Solutions For Hawaii's Hot Classrooms

Flickr / Eric Rolph
Flickr / Eric Rolph

Sweltering summer temperatures have put the heat on the Department of Education to cool Hawai‘i classrooms. The DOE says they’re installing 250 portable AC units across the state. But as HPR’s Molly Solomon reports, some experts are hoping the department will also consider long term solutions to beat the heat.

Molly Solomon
Credit Molly Solomon
It's become routine for temperatures in many of the classrooms at Campbell High in Ewa Beach to creep into the low 90's.

Whether it’s a classroom or an office, when you’re talking about hot buildings, a good place to start is the roof, says Stephen Allen, an HPU professor who teaches courses in sustainable building. “Most of the heat gain for the buildings comes in through the roof.”

Allen says there are several low cost and low tech solutions that could be adopted by Hawai‘i schools. One option is something he calls a cool roof. “That’s a reflective coating that you can apply just like thick paint,” said Allen. It’s also relatively inexpensive, and costs about 2 dollars a square foot. “It’s just like wearing light colored clothing in the summer as opposed to the dark colors,” explained Allen.

Lighter colored roofs tend to reflect heat energy back into the atmosphere. While darker roofs absorb more heat, warming the buildings they cover. “It’s basically a way to add the shade to the building without having to grow trees or put up a giant reflector,” said David Garmire, an electrical engineer professor at UH M?noa whose research focuses on innovation. He’s part of a group that’s developing a skin that could be laid over the top of a building, significantly reducing the heat. “If this could be thin enough and inexpensive enough,” said Garmire. “This layer might be a viable option.”

Research shows cooling roofs are a low cost alternative and cities that use them are starting to see results. A study out of Lawrence Berkeley National Laboratory found that buildings with light-colored, reflective rooftops lowered temperatures by up to 0.2 degrees Celsius. And last year Los Angeles passed a law requiring all new and renovated homes to install cool roofs. But HPU professor Stephen Allen says in Hawai‘i, cool roofs are still a relatively new concept. “They’re not as well known,” said Allen. “You don’t have people crying out for reflective coatings on the roof. They’re crying out for air conditioning.”

But air conditioning is very expensive, setting up some difficult choices for schools. According to the DOE, the estimated cost of installing AC at all public schools is $1.7 billion. “You need to decide are you going to just cool the hottest classrooms with the relatively expensive air conditioning,” said Allen. “Or are you going to use the lower cost, low-tech solutions and make more of them a little bit better?”

The DOE says it’s considering all options, not just during this record year, but also for the longer term.

Molly Solomon
Molly Solomon joined HPR in May 2012 as an intern for the morning talk show The Conversation. She has since worn a variety of hats around the station, doing everything from board operator to producer.
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