Energy savings and seismic risk mitigation are the main issues regarding the refurbishment of traditional buildings. Referring to historic buildings, we have to take into account, as design requirements, the cultural sustainability, which means the respects of the cultural value of the built heritage. Therefore, for historic buildings is not acceptable to adopt the conventional design choices applied to newer buildings on energy efficiency and seismic risk mitigation. Generally, the design on the built heritage requires a careful cognitive phase for firstly to identify the performance deficits and subsequently to define which actions are compatible with the cultural value of each building, according to a “case by case” approach. In Italy, specific guidelines have been elaborated on cultural heritage but such guidelines are not integrated into a single methodological process. This paper, through the study of two historic buildings, aims to identify the relationship between the two specialisms, seismic and energy, within an integrated approach. As a result, this study proposes an innovation process characterized by the integration of these two protocols within the cognitive phase and, especially in the pre-diagnosis phase; this phase is identified in the standard diagnosis (Energy approach) and in the LV2 knowledge (Seismic empirical approach).

The research proposes a novel and expeditious approach starting from direct and SfM (Structure from Motion) surveying up to H-BIM to provide a supporting tool to the knowledge of traditional bell towers, also useful for the seismic vulnerability assessment. The research draws on the possibility to enrich the H-BIM model with a semantic layer that takes into account the vulnerability indicators as defined in 2011 Italian Guidelines for the assessment and reduction of seismic risk of cultural heritage. Starting from 3D data survey, passing through the historical and constructive analysis, and the semantic classification of parts, the workflow foresaw the setting up of a semantic layer creating parameters to be assigned to each architectural component of the building and according an expeditious check-list which focuses on empirical knowledge of bell towers. This kind of information stored in the model could be very useful in situations that require particularly timely decision-making, such as in the case of calamitous events.

Summarizing the most recent studies about scientific approaches to the theme of building reuse, we propose a metadesign strategy applied to the single hall churches in Catania’s historic centre. We have performed a census and analyses on them from a morphological, technical and thermo-physical point of view. We also conducted an analysis of the urban settlement system in which these historic buildings are located, in order to verify compatibility with the "new" potential uses. However, a critical issue emerges regarding the possibility to standardize the decision-making processes involving historic buildings with a high cultural relevance.This study proposes a meta-approach to the problem of compatible reuse, looking at the specificity of disused or little used religious buildings. After making a short state of art, a cataloging and expeditious anamnesis, we have analysed a framework of needs that would consider the settlement demands in the urban context of Catania. We performed, at the end, an assessment of compatibility of reuse that satisfies the historic building safeguard, the reversibility of possible action and the requirements of the new undertaken functions.