Acoustic performance and sustainable restoration in historical religious buildings: A review of case studies in the last decade

Abstract

Historical religious buildings represent A convergence of architectural heritage, spiritual symbolism, and acoustic performance. These structures are designed not only for worship but also for ritual soundscapes, which must be preserved when adapting them to contemporary environmental and comfort standards. The process of restoring these spaces requires a sensitive balance between maintaining cultural integrity and improving acoustic functionality, especially in the context of sustainable retrofitting. This paper presents a structured literature review of acoustic and environmental interventions in historical religious buildings over the past decade. Peer-reviewed publications from 2013 to 2023 were retrieved from Scopus and Web of Science using keywords such as “acoustic restoration,” “sustainable materials,” and “heritage conservation.” Inclusion criteria focused on case studies that documented acoustic performance metrics (e.g., reverberation time, speech clarity) or described material interventions aimed at sustainability. The selected buildings span Christian, Islamic, Hindu, and Jewish traditions and reflect diverse geographic contexts. The review identifies critical trends in acoustic rehabilitation, including the application of natural fiber materials (e.g., sheep wool, cork, and cellulose), minimally invasive spatial modifications, and reversibility in retrofitting strategies. Case studies are examined for their ability to meet both historical preservation requirements and acoustic benchmarks such as RT60, C50, and STI. The integration of environmental principles, including Life Cycle Assessment (LCA), is also explored. This study contributes to the field by synthesizing recent advancements in sustainable acoustic design, offering practical frameworks for preserving the acoustic identity and cultural symbolism of sacred heritage architecture. By bridging acoustical engineering, material science, and conservation practice, the paper provides multidisciplinary insights for architects, conservationists, and researchers engaged in the adaptive reuse of religious heritage buildings.