## 3 Agro-Wastes as Building Insulation Materials
The thermal conductivity of the sample wheat straw insulation, featuring fibers aligned perpendicular to the heat flow, exhibited a remarkable reduction of 38% compared to that of normal bales. Similar results were revealed previously by other researchers [86; 87]. [PERSON] et al. incorporated peanut shells as an additive in bricks and reported a thermal conductivity of 0.155 W/mK at 25 \({}^{\circ}\)C [88]. This finding was in agreement with a previous paper, wherein a thermal conductivity of 0.09 W/mK was obtained using peanut shells [89]. In another noteworthy paper, [PERSON] et al. developed an aerogel from pineapple fibers using polyvinyl alcohol (as an adhesive agent) and water, resulting in a material with 99% porosity [90]. The results demonstrated a very low thermal conductivity for this aerogel, reaching up to 0.030 W/mK. They constructed thermal insulation with triple the performance compared to conventional materials. This improvement was also observed for sound insulation. The capabilities of pineapple leaves were also lately investigated by [PERSON] et al., revealing that pineapple leaf composites showed better thermal properties than commercial products, including asbestos and polyethylene terephthalate fibers [91]. In comparison to glass fibers, the results showed similar values. Concerning the sound absorption parameter, the pineapple leaf fibers outperformed glass fibers, performed similarly to asbestos fibers, and exhibited lower performance than polyester fiber composites. In conclusion, various tested agricultural by-products, including tea waste, sugarcane bagasse, corn cobs, and sunflower stalks, have shown competitive thermal conductivity, comparable to or better than conventional substances such as glass wool and gypsum. The same result was reported for incorporating several natural fibers together. Specific studies on wheat straw showed that the orientation of the straw influences its thermal conductivity, contributing to improved insulation efficiency, which should be investigated further. Moreover, innovative approaches such as developing aerogels could be a promising technique, offering a potential alternative to conventional materials. Advantages and Disadvantages of Agro-Materials as Insulation  
The features of biowastes vary depending on their chemical structure, the type of plant used, the production location, the local climate conditions of the products, and growth and harvesting conditions [92]. While there are several advantages to constructing products from agro-wastes, they also have some drawbacks, as shown in Table 2 [93; 94; 95; 96; 97; 98]. Furthermore, it is important to ensure the proper utilization of these resources. Having an understanding of the disadvantages associated with using agro-wastes in building materials will allow the prevention of problems that may arise. In addition, these properties can be improved and optimized through specific treatments to transform agro-wastes into better materials for construction. [PERSON] and [PERSON] found that wood waste could marginally provide better thermal insulation compared to conventional inorganic fibers, but the result was close to natural fibers. This improvement was ascribed to the superior hygric properties of wood waste [99]. [PERSON] et al. pointed out another drawback of using agro-waste for insulation. They emphasized that these materials need to be treated to combat flammability and fungi threats, a parameter that causes more costs and problems later on [80]. Moreover, the volatile organic compounds emitted from agro-waste materials have been evaluated by researchers and a negative effect of these compounds on human health was monitored [100].