Natural Buildings: Integrating Earthen Building Materials and Methods Into Mainstream Construction
Creators: name: Ben-Alon, Rachel
Publisher: name: Carnegie Mellon University
Year: 2020
Subjects: subject: 120199 Architecture not elsewhere classified
subject: FOS: Civil engineering
subject: FOS: Civil engineering

description: Earthen materials are critically needed for modern building to dramatically reduce carbon-intensive and extractive construction practices, and to improve comfort, health, and community engagement. Light straw clay, rammed earth, and cob assemblies provide high thermal inertia and high hygrothermal performance, resulting in optimal indoor environment for occupant’s comfort and health. <br>Despite their advantages, earthen materials are not widespread. For some, there is a perception that earthen materials are “poor-mans materials” and low-tech. For others, the technical data is inadequate to quantify their true performance for different climates. Lastly, earthen materials are not comprehensively represented in building codes and standards. <br>To address both the benefits and gaps, this thesis completes performance and policy assessments to mainstream implementation of earthen materials in the construction industry. The dissertation undertakes: (1) Perception analysis that identifies how negative perception on earthen building can be revised; (2) Technical analysis through environmental Life Cycle Assessment (LCA) of earthen materials compared to conventional building materials in six climates; and (3) Policy repair analysis for earthen building codes and standards towards the development of comprehensive earthen building codes. <br>The perception analysis reveals the importance of health and indoor quality data to influence homeowners, of environmental data for policymakers, and the importance of reducing building permitting barriers, especially for compressed earth block and rammed earth assemblies. <br>The environmental LCA shows that earthen assemblies significantly reduce environmental impacts compared to the benchmark assemblies of wood and concrete assemblies. Using in-depth LCI and LCA analysis, the thesis quantifies that the embodied energy demand is reduced by 62-71% by shifting from wood or concrete to earthen assemblies. In addition, the embodied global climate change impacts are reduced by 85-91%, the embodied air acidification is reduced by 79-95%, and the embodied particulate pollution is virtually eliminated. The operational impacts are shown to be highly dependent on the hygrothermal properties and climate zone, but in all cases, earthen assemblies outperform conventional assemblies with light straw clay and insulated rammed earth the top performers for all 6 climates. <br>Finally, the policy repair analysis provides strategic solutions to address the unfamiliarity and underdevelopment of earthen building codes, by use of successful precedents from around the world. The concluding recommendations are to advance the permitting processes in the absence of local earthen building codes and to establish a national organization for Earthen Building to lead and contribute to the development of an international comprehensive earthen building code. This doctoral thesis contributes critically needed environmental quantification and policy recommendations to catalyze the advancement of healthier and more environmentally sound commitments to earthen construction worldwide. <br> <br>