WHAT IS A “NATURAL INSULATION MATERIAL”? ASSESSMENT MODEL BASED ON THE LIFE CYCLE

So far, strategies to reduce the environmental impact of buildings focused on lowering the energy needs. Improving the characteristics of the building leads to a lower heating energy demand but also needs more construction materials to be used, especially insulation and airtightness materials. In the Walloon Region, a system of financial subsidies for envelope insulation has been implemented. In addition to the basic subsidy, an additional one of 3€/m² is granted if a «natural insulation material» is used. « Natural insulation material » is currently defined by the Ministerial Decree of the Walloon Government as a material containing 85% or more fibers originating from plants or animals, or cellulose. The present contribution aims to analyse and improve this current definition. The authors show that a pertinent choice cannot only be based on raw materials composition but must refer to many other criteria, taking into account the whole life cycle of the material. An assessment model and a weighting of the criteria were developed and tested on 39 generic materials based on the data coming from available database and scientific literature.