Emil Traian Gligor

In the current context, where sustainability, energy efficiency, and reduction of environmental impact are omnipresent themes, the need and interest for conservation, restoration, and reuse of heritage buildings is a topic of real interest. The city of Oradea, engaged in the last decades on the path of a sustainable urban regeneration, has managed to bring back to life part of the valuable Art Nouveau architectural treasure it inherited from previous generations. This paper presents a part of a much wider research and studies on Art Nouveau buildings in Oradea, in the context of the needs arising from the many problems identified with the start of conservation and restoration works. After an introduction on the link between heritage buildings and sustainability and a review of the current context in Oradea related to this topic, one of the emblematic buildings under renovation, the Ullmann Palace, is presented, as well as the results of some physical-mechanical tests carried out. This is followed by some discussions on the innovative and sustainable character of Art Nouveau buildings and the importance of carrying out high-quality conservation and restoration works that are environmentally friendly, safe, and sustainable.

External and internal microclimatic conditions, biodeterioration, anthropogenic factors, etc, influence the natural stone support for artifacts and built heritage. Based on this fact, the present study explores the effectiveness of nano-TiO₂ in preserving and enhancing the durability of natural stone used in the façades of heritage buildings, focusing on the Markovits-Mathéser House in Oradea Municipality, Romania. The investigation involved treating rock samples (fossiliferous limestone) with 2% and 5% nano-TiO₂ solutions and subjecting them to simulated extreme climatic conditions for the analyzed area in a controlled climatic chamber for six months. The treated samples demonstrated a significantly higher compressive strength than untreated benchmarks. SEM analyses confirmed that nano-TiO₂ formed a protective layer, filling micro-cracks and pores, thereby enhancing the stone’s resistance to environmental stressors. The study also found that the nanoparticle coating maintained its integrity under extreme temperature and humidity variations, with only a slight decrease in surface coverage. These findings suggest that nano-TiO₂ coatings significantly improve heritage building materials’ mechanical properties and longevity. However, the study highlights the importance of careful application and long-term evaluation to ensure environmental and health safety. Overall, nano-TiO₂ presents a promising solution for the conservation of cultural heritage, offering enhanced durability and protection against climatic and environmental challenges. Further research is recommended to optimize application workflow and formulations for broader and more effective use in heritage conservation.