A review of unconventional sustainable building insulation materials

Building insulation is commonly realized using materials obtained from petrochemicals (mainly polystyrene) orfrom natural sources processed with high energy consumptions (glass and rock wools). These materials causesignificant detrimental effects on the environment mainly due to the production stage, i.e. use of nonrenewablematerials and fossil energy consumption, and to the disposal stage, i.e. problems in reusing orrecycling the products at the end of their lives. The introduction of the concept of “sustainability” in building designprocess encouraged researches aimed at developing thermal and acoustic insulating materials using naturalor recycled materials. Some of them, such as kenaf or wood fiber, are already commercialized but their diffusioncould be further improved since their performance is similar to the synthetic ones. Others are currently understudy and their development is only at an early stage. The goal of the paper is to report a state of the art of buildinginsulation products made of natural or recycled materials that are not or scarcely commercialized. Comparativeanalyseswere carried out considering in particular thermal characteristics in terms of thermal conductivity, specificheat and density. Data on the acoustic performance of the materials were also reported. Life Cycle Assessmentdata were finally collected, in order to put in evidence the environmental advantages of these materials.Particular attention was paid to researches focused to exploit local materials and even industrial byproducts,since these approaches respectively limit transportation and disposal impacts.