Navigating housing system complexity - Part I: Conceptual framework and development of the Housing System Abstraction Hierarchy (HSAH)

Achieving adequate housing—defined as affordable, resilient, and sustainable—remains a persistent challenge in many cities, particularly in developing countries. Decades of fragmented, short-term, and sector-based interventions have produced outcomes that are unsustainable, unbalanced, and unequal, including intensified concentration in metropolitan areas, rising housing prices, expanding informal settlements, and growing pressure on natural resources and the urban environment. The root cause of these failures lies in the continued treatment of housing as a linear, sectoral issue rather than as a complex system shaped by interdependent economic, social, environmental, institutional, and engineering-technical dynamics. To address this gap, this study introduces the Housing System Abstraction Hierarchy (HSAH), a framework grounded in the Abstraction Hierarchy (AH) model. The AH model provides a unique analytical advantage: it explicitly represents the hierarchy of human values and policy rationales (Why) alongside the functional and physical mechanisms through which these values are operationalized (How). This capability enables the framework to uncover hidden interdependencies, unintended consequences, and structural disconnections between high-level policy goals and real-world functional processes—issues that traditional reductionist or sector-based models often fail to identify. The HSAH organizes the housing system into five abstraction levels comprising 176 components, providing a structured multi-level representation that allows analysts to trace systemic relationships, identify leverage points, expose mismatches between policy intent and physical performance, and track how interventions propagate across the system. Designed as a conceptual and structural tool, the framework strengthens the analytical capacity of urban policymakers by providing a multidimensional understanding of housing as an interconnected urban system.