# Improvement of Buildings' Air Quality and Energy Consumption Using Air Purifying Paints
## 5 Conclusions  
The current study deals with the improvement of IAQ and energy consumption in buildings through the application of an innovative photocatalytic paint. The synthesis route of the photo-powder, mixing procedures with the paint matrix, and real-scale application are described. The main outcomes of the above procedures are summarized as follows:  
* Fe-doped TiO\({}_{2}\) was prepared successfully using an easy and cost-effective co-precipitation process. In the case of Fe, doping shifted the optical absorption edge to the visible region significantly.
* The photocatalytic paint formulation has the same physicochemical and application characteristics as the commodity paints while presenting significant photocatalytic properties in terms of air pollutant elimination under real-scale application.
* The real-scale application of the photo-paint is shown with lower photocatalytic performance than the corresponding photo-powder, which was tested under a laboratory scale. The reason for the lower activity of the paint compared with powder is the polyparametric conditions (such as humidity, temperature, initial concentration, etc.) in the real-scale application.
* The ability of both organic and inorganic paints to photocatalytically remove NO was higher than toluene. The chemical structure of the pollutant plays a significant role during the oxidation reaction with the photocatalyst. Although the removal rate of toluene was lower than NO, it was very promising for IAQ applications.
* As a result of IAQ improvement, which was obtained from the application of the photocatalytic paint, the ventilation rate was reduced. Accordingly, the energy consumption in the \"green\" room was reduced by more than 7% compared to the \"conventional\" room.
* Although a real-scale application was conducted in the frame of the current work (Demo Houses), the latter was performed under controlled conditions (initial pollutant concentration, light intensity, access restrictions, etc.). To that end, there is a need for real-world building applications in order to prove the efficiency of photocatalytic paints to improve IAQ on-site. The latter is ongoing in the Hellenic Naval Academy and the results will be presented in a future manuscript.  
Conceptualization, T.M., V.B. and E.G.; Data curation, T.M., P.P., E.S., E.G. and G.C.; Investigation, E.G., P.P., E.S., V.B., G.K., G.C., A.P., K.T. and A.N.; Methodology, E.G., A.P., G.K., T.M., V.B., K.T., E.G., A.P. and A.N.; Project administration, T.M.; Writing--original draft, T.M.; Writing--review and editing, T.M., V.B., E.G., K.T. and A.P. All authors have read and agreed to the published version of the manuscript.  
This work was supported by LIFE VISIONS project (LIFE19 ENV/GR/000100), with the contribution of the LIFE Programme of the European Union. This work reflects only the authors' view and CINEA is not responsible for any use that may be made of the information it contains.  
Not applicable.  
**Data Availability Statement:** Dataset available on request from the authors. The raw data supporting the conclusions of this article will be made available by the authors on request.  
Conflicts of Interest: Authors [PERSON] and [PERSON] were employed by the company VITEX S.A. The remaining authors declare that the re-search was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.