Abstract The goal of energy efficiency in buildings is a driving force for constant innovation in the construction industry. The opportunities are searched either in cutting edge solutions but also in basic components. The development of thermal renderings and thermal plasters is a recent trend in the market, which aims at lowering the envelope's U-Value with upgraded thermal resistance of its components. The paper has the objective of presenting evaluation schemes that demonstrate the potential and allow for durability assessment of a gypsum based thermal plaster to be applied as interior rendering on walls and ceilings. The first part of the work focus the laboratory characterization of the product. It relies on the addition of low weight aggregates to reduce density and hence heat conductivity. In addition to a lower conductivity, these materials demonstrate a higher moisture capacity, resulting in a solution that can present benefits not only for energy efficiency but also for the passive control of relative humidity. Accelerated ageing tests were also performed, to assess the durability of the product. In a second part, hygrothermal simulations were performed to evaluate the potential benefits of the product and to detect hygrothermal risks that can result from its application in specific environmental conditions.