There are three ways to transfer heat: Conduction (through a solid material), Convection (through air space) and Radiant (reflective heat transmission.) The Oliver uses materials and construction techniques to take advantage of all three. The fiberglass hulls provide conductive insulation while the built in air gap between the inner and outer hull provide convective protection just like you would find in a double sided insulated cup. The Oliver is fully insulated between the exterior and interior shells with an insulated double-sided radiant barrier, which is best described as follows: "Reflective aluminum foil on each side of a 5mm (13/64 inch) polyethylene bubble center." "*Polyethylene Bubble + Radiant barrier + Vapor Barrier + Air Gap Barrier". This unique material provides a combination of radiant, convective and conductive protection. The foil radiates heat back into the camper in the winter or away from the camper in the summer. The foam insulation is infused with billions of tiny air bubbles that provide convective protection while the foam itself provides conductive protection. At only 13/64" thick this powerful product provides an R16 insulation rating. You would need approximately 4 3/4" of standard fiberglass batt insulation to equal this performance. The insulation we use serves as a radiant, vapor and air barrier making camping in any temperature a pleasurable experience.