Enviromental impact assessment of innovative nearly-​zero carbon building materials

Abstract

The building sector is responsible for around 40% of global greenhouse gas emissions and a large contribution comes from the production of building materials. Development and implementation of solutions to reduce the embodied impact of buildings is crucial to reach global decarbonization goals.

This study, which is done in a European context with a focus on Switzerland, investigates the production- and transportation impact of several innovative building material products and evaluates their potentials in new construction and renovation.
Mass and energy flow analysis of production processes is done and used as a foundation for cradle-to-gate life cycle assessments of the products. A case study building is used to perform building level LCAs of different material choice alternatives. Furthermore, an evaluation of
energy recovery from bio-based demolition waste is done and up-scaling potential of biobased materials is estimated in terms of land use demand.
The results show that bio-based insulation materials, such as straw panels and grass fiber have low upfront GHG emissions, beneficial carbon storage, good energy recovery potential after service time in buildings and their up-scaling is feasible in terms of land use demand.
Furthermore, straw and grass fiber insulation products can be transported between countries in Central Europe without overshooting impacts of using locally produced conventional materials. Transportation impact analysis further shows that calculation of emissions is sensitive to the density of materials, especially when dealing with transport of low-density materials.

Moreover, the results show that the most effective material substitution in terms of lowering embodied emissions is using clay-based non-cement materials instead of cementitious materials where possible. It is not feasible to build any of the new construction
alternatives, studied in this work, in a climate neutral way. However, a deep renovation, where everything is replaced except for the load-bearing structure, can be done in a climate positive way if the beneficial biogenic CO2 storage is considered.