Advanced modelling of the buildings energy efficiency by envelope's air layer optimization

Abstract

With the continuous rise in heating costs, energy efficiency has become an increasingly critical aspect of building design and construction. One important factor influencing thermal performance is the air layer within the building envelope, which, if not properly optimized, can lead to unnecessary material costs, increased condensation risks, and diminished insulation efficiency. This study evaluates the impact of air layer thickness on thermal insulation performance and moisture behaviour, focusing on the thermal, economic and durability implications of its oversizing. A systematic analysis is conducted by incrementally increasing the air layer thickness, from 2 cm to 18 cm (in 2 cm steps), to assess its thermal flux influence, temperature distribution and condensation formation. Numerical modelling using RDM6 and Ubakus software provides key insights into temperature variations, thermal resistance (R-value) and potential dew point formation. The results indicate that beyond a certain thickness, further increasing the air layer has a negligible impact on energy efficiency while potentially shifting the dew point into critical layers, leading to condensation accumulation, reduced insulation performance and long-term material degradation. This study highlights the importance of optimizing air layer thickness to prevent moisture-related issues and inefficient thermal performance. By using readily available materials and refining building envelope design, construction strategies can be improved to enhance both energy efficiency and structural durability. The findings contribute to the development of cost-effective and sustainable building solutions, minimizing condensation risks while ensuring optimal insulation performance