Beyond Structure: Defining Inhabitable Performance in Buildings

Abstract

The ability of buildings to support human occupation depends not only on structural integrity but also on their capacity to provide adequate indoor environmental performance. Despite the increasing use of indices and calculation-based models to quantify inhabiting conditions, existing approaches remain fragmented in terms of structure, parameter selection, and applicability. This study analyzes 19 calculation-based models used to assess inhabiting conditions in buildings, identifying their methodological characteristics, parameter composition, and level of applicability. A comparative framework was developed based on indoor focus, data requirements, and parameter coverage, enabling the selection of three representative models: the New Zealand Apartment Liveability Index (NZ ALI), the Healthy Housing Index (HHI), and the Building Habitability Index (Q). These models were applied to two real residential case studies using a consistent dataset of indoor environmental and building performance parameters. The results show that differences in index values are primarily driven by variations in weighting structures and conceptual focus rather than parameter inclusion. While the models share several core parameters, they provide distinct and complementary representations of inhabiting performance. The findings highlight the need for integrated, performance-oriented frameworks capable of consistently quantifying indoor habitability using measurable data. This work contributes to advancing the definition of inhabitable performance as an engineering-based concept applicable to building assessment and design.