Structural Insulated Panels (SIP's) are all the rage these days in the semi-prefab scene- a factory made panel that can be easily assembled to make a very tight, well insulated shell of a house. most are made of particle board and urethane foam, and while the result is certainly green, the materials are not necessarily so. When Treehugger looked at the University of Colorado's entry in the Solar Decathlon Competition, the wall panel they developed looked really interesting. The house is built out of a SIP that is variously called CU-SIP, Eco-SIP or Bio-SIP- it is probably so new that they have not got the marketers involved yet. It was developed and patented by Julee Herdt, a faculty advisor to the project. To quote Drew Bailey, one of her students:
"It is made from 100% post consumer paper products and formed into a honey-comb grid, then two pieces are glued together to make one 3/4" thick sheet.
We then treat these 'gridcore' panels as sheets of plywood used to make traditional SIPs. We created a form that holds two gridcore sheets 6" apart and then sprayed in a soy-based foam insulation which adhered to both sheets of gridcore making our Structural Insulated Panels.
Electrical conduit chases were placed according to our electrical layout prior to spraying foam. We used cardboard poster tubes as the conduit material, and typical plastic outlet boxes cut through the gridcore.
We will seam together our SIPs with an I-Beam type stud at every four footincrement between SIPs. These are made from simple 2x4's and OSB glued together to make an I-beam shape that will slip into the adjacent SIP's.
Unlike traditional SIP's, our panels will also be attached by a top and bottom 2x6 plate which will run the length of each wall. The beauty of this system is the light weight, extreme insulation (6" = approx. R-40) and the gridcore surfaces are of finish quality, they can be painted just like drywall!"