Evaluation of Bio-Based Earth Engineered Mortars for Low Energy and Carbon Buildings in Tropical and Subtropical Climates

Abstract

Improving the thermal performance of low-income housing in developing countries, located in tropical and subtropical regions, is one of the main challenges of the building sector. The use of mortars as building cladding is a current practice in many developing countries. Bio-based (such as bamboo particles) and earth materials have shown interesting potential for improving some thermal properties of covering mortars. In addition, bio-based earth mortars can have a lower carbon footprint than conventional mortars (typically made of cement or cement with lime) used in the building sector. The aim of this study is the evaluation of the life cycle GHG emissions of different mixtures of an engineered bio-based earth mortar mixed with bamboo particles, earth, and different cementitious materials (Portland cement, hydrated lime, metakaolin, and fly ash) and water. Four mixtures are evaluated: without bamboo particles, with 3%, 6%, and 9% of bamboo particles in volume. The thermal energy performance and carbon footprint of these mortars are evaluated. From physical tests carried out in the laboratory, thermal energy simulations are carried out in DesignBuilder software considering a case study of a social housing project in Brazil, evaluating tropical and subtropical climates. Finally, the carbon footprint was performed, using the Life Cycle Assessment (LCA) methodology considering a cradle-to-gate scope. When compared with two conventional mortars (made of cement and hydrated lime), the bio-based earth mortar presents better thermal energy performance and a lower carbon footprint. We can conclude that there is a potential to improve the thermal energy performance in low-income housing and, at the same time, to reduce the mortar carbon footprint. This mortar can be produced where bamboo and cementitious materials are available, which is the case in several developing countries that are expected to have a substantial housing demand for new buildings in the coming years.