Experimental Investigation on Thermal Conductivity of Straw Boards Based on the Temperature Control Box—Heat Flux Meter Method

Abstract

Straw boards are the environmentally-friendly and sustainable materials used for building envelopes. To validate a novel alternative test method of thermal conductivity (λ), temperature control box–heat flux meter method (TCB-HFM), and better understand the thermal properties of straw boards, experimental investigation on two types of straw boards using such a method was carried out. Moreover, the control test via the conventional guarded hot plate method (GHP) was conducted to provide a benchmark. Results show that the fluctuation amplitudes of the temperature difference and heat flux density for the TCB-HFM during the steady state are much smaller than a generally acceptable limitation of 5%, and a 5.9% deviation of λ between the two test methods is in a reasonable range. It is indicated that the TCB-HFM can be regarded as an alternative test method to conduct investigations on the thermal properties of materials. Furthermore, the correlation between density and λ is explored and expressed by a linear fitting formula with the determination coefficient (R2) of 0.9193, and the formula is verified to have the feasibility to predict the λ of different types of straw bio-based materials.