Developing the Transitional System Assessment Framework (TSAF): An Evidence-Explicit Approach to Historic Building Interventions

Historic building interventions are commonly assessed at whole-project scale or as isolated technical components, leaving the mediating architectural system between inherited fabric and contemporary conditions under-specified. This study defines this object as a transitional system and develops the Transitional System Assessment Framework (TSAF), comprising four analytical layers and 17 criteria. The TSAF was developed through inductive coding and theoretical synthesis, and then examined against a structured Scopus/Web of Science verification corpus (771 unique records; 30 full-text reports in Corpus A) for documentary support, conceptual coverage, definitional conflict, and redundancy. The framework records criterion response separately from evidence confidence and type, distinguishing evidenced absence (P0), non-evaluability (NE), and non-applicability (NA). Exploratory application by the framework developers to Esma Sultan Mansion, Kogod Courtyard, and the Ħaġar Qim protective shelter produced 51 criterion-level judgements: 39 coded responses and 12 NE. Three Ħaġar Qim environmental judgements were supported by measured monitoring evidence (E3), whereas Reversibility remained unevaluable in all cases. The study shows that the coding procedure is executable by the framework developers and provides evidential transparency and limited criterion-level technical corroboration, but it does not establish assessor-independent applicability, inter-rater reliability, framework-wide validity or predictive validity. By separating documented intervention responses from unsupported performance claims, the TSAF provides an evidence-explicit analytical framework for evaluating how historic building interventions reconcile fabric retention, contemporary use, environmental mediation, and heritage compatibility.