Estimating the Vulnerability Index of a Heritage Building: Methodology Applied to the National Theatre of Costa Rica

Programmed conservation of heritage buildings requires assessment tools capable of iden-tifying vulnerabilities in a systematic and decision-oriented manner. This study proposes and applies a methodology for calculating the vulnerability index of the National Theatre of Costa Rica, with the aim of establishing a technical baseline for monitoring, prioritizing interventions, and supporting long-term conservation management. The method struc-tures vulnerability through four dimensions (systems, environment, use, and urban pres-sure), each subdivided into specific risk variables weighted through the Analytic Hierar-chy Process (AHP) and pairwise comparison matrices. The building was assessed through 33 spaces grouped into 17 zones, based on two on-site evaluation campaigns, and the re-sults were consolidated into a global assessment matrix. The findings indicate an overall low vulnerability index for the building (1.391), with similarly low values recorded for systems (1.549), use (1.450), environment (1.268), and urban pressure (1.198). However, the South Façade (1.824) and the Foyer (1.778) reached medium vulnerability levels, while several additional spaces were close to that threshold. The results suggest that use-related conditions exert the greatest influence on the overall index, whereas systems-related is-sues—particularly electrical installations—remain a relevant field for intervention. The study supports the applicability of the proposed method as an objective instrument for programmed conservation of built heritage.