3. (25 pts) Agro-waste, such as rice hulls, bark, or coconut husks, can be a valuable alternative resource for sustainable construction materials. For example, rice hulls, the protective outer layer of

rice grains, are an abundant waste product of rice farming that is typically discarded. This cellulose rich material can be used as a substitute for traditional building materials, such as wood and concrete, in the production of insulation, flooring, and roofing materials. Overall, the use of agro waste, such as rice hulls, can help to reduce the environmental impact of construction while also providing cost-effective and durable building materials. a. (10 pts) Consider the following conditions for an exterior wall built with conventional residential construction materials. • Indoor air temperature T, -22°C. Convective heat transfer coefficient to inside of wall h₂-8 W m² K-¹. • Wall layer A: Drywall (gypsum), thickness t₁ - 12 mm • Wall layer B: Fiberglass batting insulation, thickness to -38 mm • Wall layer C: Plywood, thickness tc - 12 mm • Wall layer D: Stucco (cement mortar) coating, thickness to - 10 mm • Outside air temperature T -0°C. Convective heat transfer coefficient h₂-15 W m²K¹¹. Sketch a resistance network diagram representing all of the resistances from the inside air to ambient environment. You may neglect radiative heat transfer in this analysis. Calculate the areal resistances for the stages in this network. Determine the overall heat flux loss rate through the wall. b. (5 pts) Sketch the temperature profile through the layers of this wall. c. (10 pts) Now consider a version of this wall constructed using agro-waste based materials. The four layers of the wall are as follows: • Wall layer A: Rice-hull based "Resysta" panel (properties in provided datasheet), thickness t₁ - 12 mm • Wall layer B: Bagasse-based insulation panel (from sugarcane, see Madurwar et al., 2013), thickness tg - 38 mm • • Wall layer C: Rice-hull based "Resysta" panel, thickness te - 12 mm Wall layer D: Stucco coating with 10% tree bark addition (see Ba_10 thermal conductivity in Ranesi et al. (2023), thickness to - 10 mm Calculate the total heat flux loss through this wall. Do these agro-waste construction materials achieve similar thermal performance as conventional building materials?