Utilizing agro-industrial wastes panels in developing cost-efficient thermally insulating wall claddings for residential energy retrofitting in Egypt

Local agro-industrial wastes-based particleboards and fiberboards in Egypt are manufactured mainly from sugarcane-bagasse and flax shives. These panels are used in decorations and interior claddings. This paper aimed to broaden their market to be utilized in local low-cost and simple building envelope retrofitting packages instead of conventional packages that depend on imported expanded polystyrene and wet-rendered gypsum boards. Thermal conductivities of various existing sugarcane-bagasse and flax-shives-based panels were measured to be used in developing multilayered interior claddings with adequate thermal insulating performance to increase the thermal mass of a validated non-insulated case-study residential building as recommended by the Egyptian Code for Energy Efficiency of Residential Buildings. Models retrofitted using the developed cladding assemblies were simulated using Design Builder to determine their achieved annual energy savings and predict their profitability. Thermal conductivities of sugarcane-bagasse and flax-shives-based particleboards were lower than wood-based cladding panels, with the range of 0.05–0.1166 W/mK. Moreover, the thermal conductivities of sugarcane-bagasse fiberboard had the range of 0.0926–01,111 W/mK which is significantly lower than wood-based fiberboards. Simulation results showed that both models retrofitted, sugarcane bagasse-based and flax shives-based, achieved better energy savings, 5.07% and 5.04%, than the conventionally retrofitted model, 3.73%. Furthermore, the flax-shives-based model showed higher profitability, with positive income achieved in the 15th year, than a conventionally retrofitted model, achieved in the 20th year, and the sugarcane-bagasse-based model, achieved in the 19th year. Thus, it was recommended that although flax-shives-based wall claddings were usually 14–20% thicker than sugarcane-bagasse-based claddings, they provided similarly high annual energy savings with lower initial costs and higher profitability.