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A building product developed by a Portland State University School of Architecture team could help grocery stores sustainably dispose of waxed cardboard produce boxes by converting them into insulation.

Many Portland-area grocery stores include used produce boxes in compostable waste, but because they’re coated in wax it can take up to 50 years for them to decompose. The slow decomposition time and the large volume tossed by grocery stores are reasons why on Nov. 1 waxed cardboard will be banned from compost piles at Multnomah, Washington and Clackamas county dumps.

When PSU assistant architecture professor Margarette Leite learned that officials from New Seasons Market and other Portland grocery stores were seeking an environmentally friendly way to dispose of produce boxes, she thought it would be a perfect project for a class she teaches on finding architectural uses for waste materials. In the class, architecture students came up with several ways to reuse the produce boxes, such as in building siding or shingles.

But the idea to create insulation by shredding the waxed cardboard intrigued Leite most. She’s now in the process of developing a business plan with encouragement of New Seasons Market, and hoping to find a manufacturer willing to produce the insulation billed as both effective and sustainable.

鈥淲e’re getting a lot of support from the grocery stores,鈥� Leite said. 鈥淭his is more about diverting material from a landfill and making a green product that way.鈥�

Certain types of cellulose insulation are made with standard cardboard, but that material must be purchased, she said. In contrast, grocery stores throw out waxed cardboard.

鈥淩ight now, the waxed cardboard has no value, so there’s really no competition right now for the resource,鈥� she said. 鈥淪o that’s the biggest advantage over the cellulose.鈥�

Leite and a team of three students came up with several ways to use the shredded waxed cardboard as insulation. It could be blown into walls as loose fill insulation, packed into flame-retardant fabric for panelized installation or wrapped into bales for building construction.

Tests of the product’s effectiveness in PSU’s Green Building Research Laboratory revealed that the wax coating that makes produce boxes hard to compost is actually an advantage when they’re converted into insulation, Leite said. She believes the wax is one reason why the produce box insulation performed better than traditional fiberglass insulation in the lab.

鈥淚t holds onto energy for a longer time,鈥� she said. 鈥淚t acts like what we call a thermal sink. As the wax kind of heats up, it’s storing energy so it’s a better insulator, or the wax is a barrier to hot or cold air.鈥�

Kevin Chavez, a recent PSU architecture graduate who helped develop the insulation, said the lab test results helped convince him and the rest of the team that they were working on a viable project.

鈥淭hat’s what launched this to say, 鈥極h wow, this is actually really competitive to what’s available,’ 鈥� he said. 鈥淭hen it was figuring out how to get it into a building and up to building code.鈥�

The biggest challenge was ensuring the insulation was fire resistant, Chavez said. A series of tests proved this could be achieved either by adding a flame retardant to the loose fill of waxed cardboard insulation or wrapping it in fire-resistant fabric, he said.

The project was among seven finalists that this month vied for funding through the Cleantech Challenge 鈥� part of the Oregon BEST FEST clean technology conference in Portland. The team didn’t win funding though the competition, but Leite said encouragement from officials at New Seasons and other grocery stores has convinced her to pursue licensing the product to an insulation manufacturer or start a small business to produce it.

The cost of producing the insulation should be relatively low, Chavez said.

鈥淎ll that would need to happen is shred it or fireproof it,鈥� he said. 鈥淚 think manufacturers would really like this because of how low-processing it is.鈥�

Most of the approximately 580 tons of produce received each year by New Seasons stores comes in cardboard boxes with wax coatings to protect them from disintegrating in ice used to keep fruits and vegetables fresh, said Teak Wall, New Seasons sustainability program manager. Not being able to compost these boxes puts a wrench in the grocer’s efforts to avoid sending waste to the landfill.

鈥淲e realized the biggest issue for us would be our waxed cardboard,鈥� she said.

While investigating where to send spent produce boxes Wall found out that the market for reusing waxed cardboard is relatively untapped with the exception of a California company that uses it to produce fire logs. The grocer already donates some of the produce boxes it uses to this company, but officials would prefer to send the waxed cardboard somewhere closer, she said.

鈥淲e would love to get more local businesses using this,鈥� she said.

It would be great if PSU’s waxed cardboard insulation got off the ground, Wall said.

鈥淚 think it’s the coolest idea ever,鈥� she said. 鈥淚t’s almost too simple to believe that no one’s done it yet.鈥�

Developing the product was a rewarding experience, Chavez said.

鈥淚 think it’s really important that we find these little avenues to repurpose those materials that we’re already making,鈥� he said.