## 4 Conclusions  
In this study, three techniques were considered to evaluate the photocatalytic efficiency (PE) of TiO\({}_{2}\)-based coatings on cementitious materials. All methods demonstrated the  
Figure 12: UV-Vis: (**a**) dark condition and (**b**) irradiation phase. effectiveness of TiO\({}_{2}\) functionalization in increasing photocatalytic activity compared to untreated samples, confirming its suitability for self-cleaning assessments on urban facades and exterior coatings. SPC and DIP proved to be useful for monitoring esthetic changes and evaluating PE values. DIP stood out for its accuracy and accessibility, while UV-Vis offered high sensitivity and versatility, especially for the detection of a wide range of pollutants, although its application to cementitious substrates proved challenging due to the specific characteristics of these materials. The results suggest that the integration of these techniques can overcome individual limitations and provide a more comprehensive approach to the evaluation of photocatalytic materials. The ISO 10678 standard provides a robust framework for evaluating self-cleaning efficiency, particularly for smooth and non-porous substrates like ceramics, using dye degradation as a metric. However, its narrow focus on standardized conditions and substrates overlooks the complexities of cementitious materials, which are highly porous and interact differently with pollutants. To achieve a comprehensive evaluation of the photocatalytic efficiency of cementitious materials, it is crucial to adapt existing standards or develop a hybrid protocol that integrates multiple assessment techniques. Current methodologies, including SPC, DIP, and UV-Vis, offer complementary insights but remain underexplored for real-world applications. Additionally, contact angle measurements for hydrophilicity assessment should be incorporated to provide a more holistic evaluation of self-cleaning performance. The use of reference pollutants with well-defined parameters--such as Rhodamine B, Methyl Orange, phenolic compounds, and Carbon Black--along with standardized conditions for image acquisition and processing in colorimetric analyses, is essential to ensure the reliability of results. Given the intrinsic properties of cementitious materials, standardized protocols for sample preparation are necessary to enhance consistency and reproducibility across studies. These should define surface preparation, functionalization methods, and photocatalyst application techniques, ensuring comparability between different research efforts. Moreover, since photocatalytic coatings on cementitious materials are intended for long-term outdoor applications, durability tests that simulate prolonged UV exposure, climatic variations, and pollutant interactions must be included to assess long-term stability and performance. The development of standardized methodologies adapted to cementitious substrates will improve the applicability of self-cleaning technologies in built environments. Future work should focus on the development of standardized protocols that combine these methods to ensure reliable and consistent evaluations of different substrates and types of pollutants.