Thermophysical properties and energy efficiency of a sustainable construction materials produced from local natural waste

Improving the energy efficiency of buildings is crucial for reducing energy demand and moderating the environmental impact due to its large energy consumption and greenhouse gas emissions. Integrating waste into construction materials can offer sustainable and cost-effective solutions for energy-efficient buildings. This study aims to develop new construction materials (plasterboards) formed by gypsum and natural wastes (5% in mass) including Posidonia-Oceanica, sawdust, sheep's wool, and cork granules to substitute filasse in conventional plasterboards. The main objective of this work is to evaluate and compare the thermal properties of the composite materials manufactured and to determine energy saving, optimal insulation thickness and environmental impact when adding the developed plasterboards in the envelope of an office building in a Mediterranean climate. An experimental study is performed to evaluate the thermo-physical properties and a numerical simulation is conducted using design builder software to discuss the energy efficiency of these materials. Results shows that the incorporation of natural waste reduces the thermal conductivity and can reduce heating and cooling needs compared to conventional plasterboard. Specially, plasterboard made with Posidonia-Oceanica fibers which exhibits a reduction of 32 % in thermal conductivity. It achieves an improvement in energy efficiency of 8 % when it is used in roof ceiling. When used as coating-panels in building walls with a thickness of 24 cm, it achieves about 17 % of energy saving. In addition, this study determines the optimum insulation thickness leading to minimize the sum of the insulation investment and the energy costs over the building's lifetime. Four values of building’s lifespan were chosen (10, 20, 30 and 50 years). Results show that for a 10-year building life, the optimum insulation thickness is 9cm, whereas for a longer building life (50 years), the optimum insulation thickness is 19cm. It saves 15.64kWh/m2 of energy required for heating and 2.09kWh/m2 needed for cooling and reduces of about 8.8tons ofCO2 emitted. The use of natural waste as fillers to prepare plasterboards showed a good effectiveness. It provides important energy saving and reduces CO2 emissions. Creating effective insulating materials using local natural waste, could be a valuable step towards establishing a sustainable development approach.