The portables - or "temporaries" - are prefabricated classrooms designed to be shifted around as student populations wax and wane in various communities. They're designed to be sturdy, squat, modular and easily transportable.
Unfortunately, they also absorb radiant heat from the sun and turn the learning experience into an exercise in baking.
The Portable Project asked the kids to study the situation as a real-world science experiment, learning basic physics and then applying that knowledge in a hands-on environment. They researched, developed various hypothesis, developed and built models, collected data and reworked their theories and came up with a recommended plan.
It's not the best solution. That would have entailed adding two feet of adobe to the portable walls, rebuilding the roof into a high peak with an insulated attic and a solar-powered air conditioner under the structure.
But this is public school, where there isn't enough money for textbooks. Our guidelines for a solution:
This heat energy needs to be reflected back, then vented. At the same time, they discovered that there is a pool of cooler air under the structure - the air volume in the classroom actually acted as insulation.
A control model mirrored actual temperatures inside the full-size portables, on some occasions rising to 103 degrees. Every one of the student variations provided some degree of relief; in some cases, many degrees.
The "Waianae Solution" is a kind of elegant convection engine. Hot air rises and is vented through a turbine added to the roof. Radiant heat energy from sunlight is trapped in a false "attic" created with aluminum-coated bubble wrap suspended about a foot below the real ceiling. This reflects virtually all the radiant heat. As the hot air is vented, it creates a slight vacuum in the heat space that draws in cooler air from beneath the structure.
A fairly new invention, the bubble foil goes by brand names such as Astro-Foil and Reflectix. The students discovered it is terrific at blocking heat transfer. It is the recommended insulation for buildings with tight headroom, such as portables.
Justin Gomban and Lasha Salbosa check on models of "temporary" classrooms as part of the project.
Photo by Ken Sakamoto, Star-Bulletin
The Star-Bulletin bankrolled the project, and many different products were tried.
A roof paint called Snowflake was tried, for example. It worked well, but was expensive, difficult and time-consuming to apply and would have been ruined if the portable had been disassembled for shipping.
The students also discovered there was a difference between real coolness and perceived coolness. The Waianae Solution will prevent the structure from getting too hot, but the air space inside still can get stuffy. The kids recommend installing one or two oscillating wall-mount fans to keep air moving during class.
The Waianae Solution will work. But how well?
No one knows until it is installed on a full-sized structure, and careful measurements are made comparing it to unmodified structures.
The Star-Bulletin and Waianae High instructors and staff have asked the state Department of Accounting and General Services to convert a single portable at Waianae this summer to study the results.
According to Steve Fernandes of DAGS, the Waianae Solution first needs to be studied by engineers to make sure it doesn't violate any building or fire codes.
