Sustainable building envelopes: Evaluating the thermal performance of thatched roofs fabricated using coconut leaves

Abstract

Excessive heat gain in residential buildings during sunny days, especially in tropical regions, leads to increased reliance on active energy cooling systems, contributing to higher carbon emissions and energy costs. Traditional roofing materials, such as terracotta tiles are often insufficient in mitigating indoor temperature rise, necessitating the exploration of alternative, sustainable solutions. This study investigates the thermal performance of naturally available coconut leaves used as thatch roofing, comparing it with conventional terracotta tiles, to determine their effectiveness in controlling interior temperatures and reducing heat gain in buildings. To mitigate such a problem, the Near Infra-Red (NIR) light reflectivity of dried plant leaves derived from deciduous and coniferous trees was measured. The structural hierarchy of the leaves was confirmed through Field Emission Scanning Electron Microscope (FESEM), Fourier Transform Infrared Spectroscope (FTIR) and X-ray Diffraction (XRD) studies. FTIR spectra reveal characteristic vibrations of ester, cellulosic components, etc., and XRD confirms the amorphous status of cellulosic materials present in the plant biomass. To study the use of thatched roofs made using coconut leaves as a roofing element, two test huts were fabricated - one was covered using terracotta roof tiles and the other was covered using coconut leaves thatches. The thermal performances of two roofing materials were recorded on a sunny day and the results were compared. The temperature data noticed reveal the fact that the maximum average surface temperature of the terracotta roof model was 59.53 °C, while the rooftop covered with coconut thatches exhibits a temperature of 54.26 °C which is 8.8% less than the hut covered with terracotta tiles. The interior temperature recorded in the coconut thatch was 33.36 °C, which was 1.15 °C lower (34.51 °C) than the terracotta tiles-covered test hut, confirming the better thermal comfortability of thatched roof model than a terracotta roof model.