Environmental impacts of natural and conventional building materials: a case study on earth plasters

This study compares the environmental impacts of earthen plasters (based on clay) with those of conventional industrial plasters (based on cement or hydraulic lime) from a life cycle perspective. Environmental impacts were assessed via midpoint (Cumulative Energy Demand, Greenhouse Gas Protocol and Ecological Footprint) and endpoint (ReCiPe) indicators. Results show that the environmental performances of earthen materials, whose production is based on simple processes requiring relatively small amounts of energy, are substantially better than those of conventional plasters. The largest impact component is, for all plasters, the energy produced from fossil sources, which accounts for 63–85% of the overall embodied energy. However, the larger impacts of synthetic plasters stem mainly from CO2 emissions during the calcination process in cement manufacturing. On the other hand, transport is very important, at least in relative terms, in determining the overall impact of earth plasters. This highlights the importance of finding local sources of raw materials to avoid nullifying the environmental benefits of natural building products.