In the last few decades, air pollution constitutes a major global problem that results in adverse effects on human’s health, nature and the built environment. Many abatement strategies have been adopted for its combat in all these different fields. This graduation project focuses on the built environment and tackles the application of TiO2 on facades of existing buildings with historical significance in the city of Athens. TiO2 is a promising photocatalytic material, capable of neutralizing air pollutants via the mechanism of photocatalysis and under certain environmental conditions. Its use aims at a wider application in urban landscapes, in order to alleviate the air pollution levels. This widespread application can be achieved by the creation of 3 different TiO2 application levels that can be applied on the different facade components. The choice of application is realized mainly via the assessment of their NOx efficiency, the assessment of values employed in the field of conservation as well as their effect on cost. This evaluation takes place through a number of steps that a designer can follow for the selection of the suitable level as well as for the components that can eventually be modified.

In the current thesis, this set of steps/roadmap is presented and validated with the help of an actual case study, where the balconies are the main chosen facade element undergoing alterations of the 2nd level. It goes without saying that the flow can be followed and applied for different components, different buildings or even in different cities and locations. Athens is simply a representative example for this cause. Since the main goal of the project is the optimum performance of TiO2, a series of different balcony panels are designed via the manipulation of surface area and roughness, two very crucial factors for the successful activation of photocatalysis and pollutant neutralization. The panels undergo 3 different analyses: radiation, wind and NOx removal with a successive evaluation, resulting in one ideal geometry, whose NOx levels are compared to those prior to its implementation and those of the 1st application level.

The final part of the graduation project focuses on the results yielded by these different analyses and the conclusions that are pointed out and could prove pivotal for a designer. After the application of the panels to the chosen street canyon, the evaluation of the NOx abatement efficiency, the value and cost of each tested scenario, results indicate that the 2nd application level of TiO2 is more efficient than the 1st in terms of NOx removal efficiency. Nevertheless, a combination of both levels could considerably balance all 3 criteria, namely the aspect of NOx removal, values and cost.

Keywords: Urban Facades I Air Pollution I TiO2 I Air Purification I Historical Significance