## 3 Agro-Wastes as Building Insulation Materials  
One of the interesting applications of agricultural wastes is their use as a powerful material for insulation instead of conventional materials. This has some benefits like renewability, compostablity, and a low rate of thermal conductivity [76]. There is minimal difference in the thermal conductivity and sound penetration rates between agricultural materials and other conventional materials [77]. This property was also observed when utilizing wheat straw to fill in clay-fired hollow bricks. It was found that the wheat straw could effectively save up to 69% energy, which was higher than straw-free bricks. [PERSON] et al. [78] emphasized that the application of tea waste improved some mechanical properties, i.e., thermal conductivity (42%), porosity (56.5%), and specific gravity, and highly reduced the compressive strength of clay-fired bricks (by 79% when the added waste was at 12.5%). They reported that the insulation-related attributes of the bricks containing tea waste were increased. The authors asserted that tea waste could be utilized for construction and insulation purposes up to a 10% threshold. However, for insulation purposes, it could be used in quantities exceeding 10%. Experimental studies have also found a high similarity between corn cobs and extruded polystyrene from the point of view of their chemical composition. These findings suggest that corn cobs have enough thermal properties for applications in construction [14]. In a different study, [PERSON] et al. studied jute, flax, and hemp, concluding that the appropriate combination of these natural fibers yields thermal insulation results comparable to common materials [79]. [PERSON] et al. utilized sugarcane bagasse waste to assess its thermal and sound insulation properties and found acceptable results for these purposes [80]. They achieved a thermal conductivity of 0.034 W/mK for the sample with a density of 100 kg/m\({}^{3}\), and this value was increased to 0.042 W/mK for the sample with 200 kg/m\({}^{3}\) density. [PERSON] et al. used sugarcane bagasse fibers to investigate the thermal features of reinforced cement composites [81]. They emphasized that the best ratio of added fibers was 1.5%, which increased the thermal diffusivity from 1.18 to 1.58 \(\times\) 10\({}^{6}\) m\({}^{2}\)/s. The authors also reported that adding this natural fiber lowered the thermal conductivity of the cement composites. Overall, it was found that bagasse, rice husk, and coconut coir exhibit lower thermal conductivity among agro-waste materials [82]. [PERSON] et al. utilized sunflower stalks in combination with some other agro-waste materials to produce rectangular blocks of 30 \(\times\) 40 \(\times\) 2.5 cm\({}^{3}\) under different pressures [83]. They tested both the mechanical properties as well as the thermal transmittance of the samples. They obtained the lowest heat transfer coefficients for the samples containing sunflower stalks. In a separate study, [PERSON] et al. examined a composite material consisting of vermiculite, sunflower stalks, wheat stalks, and gypsum for building insulation. They recorded thermal conductivity coefficients ranging from 0.063 to 0.334 W/mK for the samples based on the density of the samples [84]. More specifically, the minimum thermal conductivity was 0.166, which was recorded for the sample containing 25 g sunflower stalk sponge, 50 g wheat stalks, 150 g vermiculite, 140 g gypsum, and 110 g water with a density of 0.166 g/cm\({}^{3}\). For better comparison, this parameter is 0.4 for materials like gypsum, and for glass wool it is 0.04. [PERSON] et al. assessed the effects of the orientation and position of wheat straw within wall insulation on its humidity and thermal properties [85]. Their results showed a 38% reduction in thermal conductivity; in addition, the designed package reduced the moisture permeability by up to 76%.