Raw Earth as a building material from an LCA point of view

Sammanfattning

Material choice during design and construction phase is one of the key leverages to reduce the high environmental impact associated to buildings during its life cycle. In this context, natural materials can be introduced to decrease the use of traditional construction materials like cement-based and to reduce the climate impact. The aim of this study is to apply a hands-on life cycle assessment (LCA) method to measure the climate impact when earthen elements is in building’s structural parts from a point of view This material, extracted directly from the earth’s ground surface, is widely used for dwellings in warm climate areas all around the globe. Overcoming preconceived ideas and mental bias, this study set a frame for advised building methods to align the use of raw earth with a low-carbon construction. The study is based on data from two actual building projects, in France and Saudi Arabia. Local context is used in combination with LCA standards and EPD data on construction materials and their emission of greenhouse gases (GHG) contributing to climate impact (GWP, Global Warming Potential). In the context of a full structure LCA, functional units are chosen accordingly, which consider load-bearing capacity and structure characteristics. Different scenarios of structures based on the material used and the architectural demand are developed for each project to allow a fair comparison and analysis. Simplified life-cycle inventories are used to allow for full control of the parameters used for the construction design and results traceability. Resulting calculated climate impact point out the preponderance of the transport and additives significantly in the earth material contributes to the total emissions of the building element. From this first result, optimization of these significant parameters that have been applied show relatively low emissions, when raw earth materials are used without cement addition and compared to traditional concrete construction. Secondly, for complex earthen structures the same result is achieved with low associated climate impact, that is demonstrated by applying an eco-building process approach. The result illustrated here is a practical example that of use of natural materials like raw earth usage has a potential for eco-friendly building. Amongst limits of this study is worth mention the focus on climate impact without consideration for the other environmental impact categories, or that the actual the lifespan of earthen structure may differ compared to traditional material. These are aspects that might be assessed in future studies.