Balancing Performance and Sustainability: A Study on Rice husk in Innovative Plaster Formulations

Pursuing higher energy efficiency and reduced environmental impact is a key strategy in building sector renovation. Sustainable building design increasingly promotes the use of materials incorporating natural or recycled components. Within this framework, the present study investigates the hygrothermal performance of three innovative plaster formulations to assess the effect of partially re-placing expanded amorphous silica - known for its energy-intensive production process - with a more sustainable agricultural by-product, i.e., rice husk. The three formulations differ in the percentage of rice husk content: 5.0%, 7.5% and 10.0%, respectively, substituting equivalent amounts of expanded silica. Experimental measurements of thermal conductivity, heat capacity and thermal diffusivity are carried out to assess the absolute behavior of each mix under controlled laboratory conditions. Results show how the introduction of rice husk slightly reduces the overall thermal performance of the plaster, particularly in terms of thermal conductivity, but brings advantages in terms of breathability and moisture regulation, contributing to improved indoor comfort and environmental sustainability. This research contributes to the growing body of knowledge on sustainable building technologies by proposing practical solutions to reduce the environmental footprint of construction materials, while maintaining a balanced compromise between technical performance and ecological criteria.