Inspired by the woods of Vermont, a US biotechnology startup have developed a system for using agricultural byproducts with fungal mycelium (a natural, self-assembling binder) to grow high performance insulation. Ecovative Mushroom® Insulation is seen as a viable competitor to plastic foams that can be found in both in packaging and building insulation, for which the project recently won second place in the Cradle to Cradle Product Innovation Challenge.
Existing rigid board insulation (such as extruded polystyrene) is made of finite petrochemicals and "often includes high global-warming potential blowing gasses that seep out over time, lowering the aged R-value." In addition, loose fill and batt insulation can settle, especially in a movable tiny house, which compromises effectiveness. Furthermore, in order to meet fire safety codes, nearly all rigid board and loose fill insulation materials are made with harsh flame retardant chemicals.
Ecovative's alternative process involves live Mushroom Insulation being packed in between the walls. "In three days, the mycelium grows and solidifies the loose particles into air-sealed insulation, while also adhering to the pine boards and creating an extremely strong sandwich. The result is similar to a structural insulating panel; this layer of continuous insulation has no thermal bridging. Over the course of about a month, the Mushroom Insulation naturally dries and goes dormant." According to the company, "mushrooms will only fruit through gaps or due to improper construction, and can be easily trimmed off with a knife before they produce spores."