Development and thermal characteristic study of an integrated phase change material earthbag unit for temporary housings

Abstract

The increasing demand for temporary housing in many developing countries necessitate the use of sustainable and affordable construction options. Earthbag units have the potential to be integrated into such housings as they are inexpensive, sustainable, and straightforward material options for building structures. Nevertheless, due to their thermal characteristics, earthbag units cannot provide a thermally comfortable environment.Thus, the present study focuses on developing an environmentally and sustainable earthbag unit integrated with phase change materials (PCM) to convert severely harsh indoor spaces to moderately harsh ones. For the design and development of earthbag blocks, several units are developed with varying amounts of PCM encapsulated in expanded perlite (EP) and expanded graphite (EG) within each unit, including block A (reference), Block B (PCM 2.2% of sample weight), C (4.3%), and D (6.5%). An experimental study is then conducted to understand the microstructural properties of the embedded PCM composite in soil. Following this initial study, practical differential techniques, including differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron microscope (SEM), thermal conductivity, and Oozing circle test, have been employed over the developed units to measure their thermal characteristics. Test results from DSC and TGA show good thermal stability of PCM and PCM composites, while SEM results indicated that PCM is well distributed within the pores of EP at 50%EP of the PCM weight. The study found the average indoor surface temperatures by block B, block C, and block D to drop compared to the reference block about 1.2 °C, 3.3 °C, and 4.1 °C, respectively. This clearly shows the benefit of integrating phase change materials in an earthbag unit.