Towards a sustainable decision analysis approach for moisture-safe building envelope design

Energy-efficient building designs, notably through adding insulation, can reduce energy consumption and greenhouse gas emissions by over 40 %, but may also increase risk of condensation. Therefore, a comprehensive decision analysis approach is essential for selecting optimal building envelope assemblies while considering their hygrothermal, economic, and environmental implications. This study introduces a novel decision analysis method based on the inutility decision analysis (IDA) concept, in which the building envelope with the lowest inutility is considered the optimal choice. Initially, different building envelope assemblies were assessed through probabilistic hygrothermal analysis combined with a machine learning metamodel. Subsequently, the environmental and economic consequences associated with each assembly were quantified by integrating moisture-related damage into these assessments. Combining these outputs yielded inutility indices for the case studies, guiding the selection of the most optimal alternative. The results indicated that an external wall, with a minor risk of moisture-related failure, may outperform other alternatives when considering economic and environmental metrics. However, the final decision on the acceptability of such risk should rest with the customers or owners. Balancing the trade-off between performance longevity, cost, and occupants’ health is crucial.