Numerical simulation of the effect of bamboo composite building envelope on summer overheating problem

Abstract Bamboo is one of the materials that have recently attracted considerable interest in sustainable buildings as they are fast growing, retaining thermal and mechanical properties similar to structural wood products, and considered effective CO2 absorbers. Several studies tried to assess the energy performance of bamboo-structures for residential buildings both experimentally and numerically. This numerical study presents an overview on the overheating problem and thermal comfort of four building envelopes: the original steel-bamboo with thermal transmittance of 0.65 W/m2K developed in China by Li et al. (2017) [22], a modified steel-bamboo with increased insulation with thermal transmittance of 0.22 W/m2K to comply with Hungarian requirements, brick, and bamboo-Expanded Polystyrene (EPS). Therm version 7.7.10 was used to simulate heat-transfer, DesignBuilder version 6 was applied to perform the energy analysis. We found that, if neither shading nor enhanced ventilation are applied, the critical building zone has significant overheating in all building systems, emphasising the importance of efficient shading and night ventilation in Hungarian climate. With shading and natural ventilation, the number of hours at or above 26 °C is over 1000 in the modified steel-bamboo, bamboo-EPS, and brick systems, indicating overheating during the summer. Only the original steel-bamboo building envelope performs well concerning the overheating, as the number of hours at or above 26 °C is only about 200. This is the direct consequence of this structure having the lowest insulation of all cases, and hence it has higher heat loss through transmission and can best cool down during evening. However, the original steel-bamboo has more than 100% higher heating consumption than the modified steel-bamboo, as the former building did not comply with Hungarian regulations.