Use of straw bundles in buildings for a lower environmental footprint of insulated systems

Abstract

This paper aims to evaluate the environmental footprint of an exterior wall assembly made of straw bundles and to compare it with the one of a conventional wall. The used methodology is Life Cycle Assessment. The EIMME® software, associated with the eco-invent database, is used to quantify the potential environmental impacts of the considered walls. Obviously, some steps of the wall life cycle have a small environmental footprint, for example, the consumer use step provides low impacts, while the end of life step (post-consumer) allows a “saving” (i.e., a diminution) of impacts because a part of the materials can be reused. On the other side, the raw material procurement and manufacturing steps are at the origin of the greatest impacts. Among the chosen indicators, the main environmental impacts are found to be the energy consumption, the air toxicity, the 100-year global warning, and the use and treatment of water. To minimize the impacts (environmental footprint), local producers should be preferred. The assembly is finally compared to a conventional wall realized by using glass wool and breeze blocks. According to the obtained results, the “straw wall” is shown to be better for the environment regardless of the considered indicator, excepted for the air toxicity for which the values of the two studied walls are of the same order of magnitude. It is shown that the only alternative to the conventional insulation for the environmental point of view seems to be the use of “straw walls.”