Static and Dynamic Thermal Characterization of Timber Frame/Wheat (Triticum Aestivum) Chaff Thermal Insulation Panel for Sustainable Building Construction

Abstract

Common wheat is currently the most widely grown cereal and its grains are mainly used to produce white bread. Contrary to plant seeds, the plant itself may be considered an agricultural waste which is used as an animal feed, soil fertilizer, or pelletized solid fuel to produce heat energy. While wheat straw is used widely in sustainable building construction, mostly as straw bales, the use of the thin dry husk around the grain, the wheat chaff, remained unexplored. An insulation panel made of a medium-density fiberboard (MDF) envelope and wooden studs was manufactured. The 150-mm gap between the MDFs was filled with dry wheat chaff. The thermal transmittance of the panel was determined under static and dynamic thermal conditions using a modified guarded hot box method. The results were compared to an insulation panel of the same construction that was filled with mineral wool. The thermal transmittance of wheat chaff under steady-state and dynamic conditions was 0.307 W m −2 K −1 and 0.298 W m −2 K −1 , respectively. While in steady-state conditions the mineral wool outperforms the wheat chaff insulation, after a period of dynamic thermal loading, the ability of both insulations to resist heat-energy dissipation becomes similar. In conclusion, wheat chaff agrowaste seems to be a promising environmentally friendly alternative to artificial thermal insulation. Moreover, the determination of the thermal transmittance of bio-based materials with relatively high specific heat capacities under dynamic thermal loading, provides more accurate results, compared to steady-state conditions.

Permeable Water-Resistant Heat Insulation Panel Based on Recycled Materials and Its Physical and Mechanical Properties

“…As with the thermal conductivity coefficient, the addition of husk increased this characteristic. However, in this case, this is an improvement in the characteristic that can compensate for the increase in the thermal conductivity coefficient, in the form of a higher accumulation capability of the material and the retention of heat in the walls at a slight decrease in exterior temperature [36]. However, panel cores containing husks achieved, still, a much lower volumetric heat capacity than another agriculture by-product—corn husks [37].…”

Key advances in development of straw fibre bio-composite boards: An overview

“…Similarly, surface treated wheat husk fibre BCB exhibited thermal conductivity as low as 0.0714 W m −1 K −1 [123]. Interestingly, the wheat fibre chaff showed excellent thermal conductivity coefficient under steady-state and dynamic conditions (0.307 W m −1 K −1 and 0.298 W m −1 K −1 , respectively) [141]. Several research also established the good thermal resistance of straw fibres BCB [127,[142][143][144][145][146].…”

Bio-Waste Thermal Insulation Panel for Sustainable Building Construction in Steady and Unsteady-State Conditions

“…A similar calculation was used in Burrati et al [33]. The alternative approach used previously by Pavelek et al [24] and Trgala et al [34] brought the opportunity to measure the total energy (Wh) transmitted through the sample and to find appropriate U value using dynamic conditions. Heat capacity, thermal response to real weather conditions and the influence of water and vapor content can be taken into account more suitably in the testing method compared to current steady-state conditions.…”

“…It consists of two enclosed chambers (hot and cold) kept at constant temperatures and separated by the specimen (e.g., wooden panel with agro-waste thermal insulation). Due to the temperature gradient, heat flux between the two chambers through the specimen is measured and thermal resistance of the structure is determined [24].…”