Hygrothermal Performance of Binderless Luffa Fiber Insulation Panels for Energy-Efficient Building Applications

¹ Department of Engineering Mechanics, Faculty of Applied Sciences, Ho Chi Minh City University of Technology (HCMUT), 268 Ly Thuong Kiet Street, Dien Hong Ward, Ho Chi Minh City, Vietnam
² Vietnam National University, Ho Chi Minh City, Linh Xuan Ward, Ho Chi Minh City, Vietnam
³ Department of Mechanical Engineering, The University of Danang - University of Science and Technology, 54 Nguyen Luong Bang, Lien Chieu, Danang 550000 Vietnam

^* Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Abstract

The global interest in environmentally responsible building materials has accelerated the development of insulation products based on renewable bio-resources. This study examines the hygrothermal behaviour of insulation panels fabricated from luffa cylindrica materials using a wet-forming process. Three panel types were uniformly fabricated and tested for thermal and moisture responses. Steady-state thermal resistance was evaluated at mean temperatures between 10 and 40 °C using a heat-flow-meter apparatus. All samples exhibited a linear decrease in thermal resistance with increasing temperature, reflecting the enhanced heat transfer mechanisms within the interconnected porous network. Among the panels, the specimen with the most homogeneous void structure demonstrated the highest thermal performance. Moisture uptake was analysed under controlled relative humidity levels generated by using saturated salt solutions. The samples displayed typical Fickian absorption behaviour, with equilibrium moisture contents (EMC) increasing predictably with relative humidity but remaining largely unaffected by differences in panel thickness. The EMC values converged at approximately 10, 13, and 16% for the three humidity conditions of 54, 75, and 95%, respectively. The findings reaffirm the potential of luffa-based binderless composites as lightweight bio-insulation for sustainable building applications, offering stable hygrothermal properties and reduced environmental impact.