## 4 Discussion
In this case, however, it is also noted that the building's direct impact is not high enough, compared to other potentially more commonly applied mitigation strategies and interventions, such as vegetation or urban shading, to be able to provide a noticeable improvement on the UHI reduction in the urban microclimate. * If only the indirect effect is evaluated, then it has an impact on the reduction of the building's cooling demands of the existing building situation, working as an external sun-shading skin and reducing the solar heat gains during summer. However, when compared to other shading devices on the same criterion, then the effect is similar, if not slightly less. * If the evaluation lies only on the impact on the UHI effect as an isolated scenario, as it was the main objective of the study, then the facade design performed overall better than the other shading devices, because of the additional contribution in the direct impact on the urban microclimate. * When the design is additionally being assessed as an overall dynamic facade system, including both energy and environmental performance, it brings added benefits to the building's annual operation. This is achieved by functioning as a closed-cavity double facade during the winter and, thus, reducing heat losses. In addition to that, even though the cooling demands are reduced almost equally compared to the other shading devices, the last ones operate only during warm and sunny periods. * When compared to similar state-of-the-art facade systems, the question lies mostly on feasibility variables, such as cost-effectiveness, operation complexity, and maintenance. However, merely on the energy aspect, for example, a typical double skin facade would only have positive effects during the winter, especially in a warm climate such as the Mediterranean one, and would possibly require additional sun-shading within the cavity, since it would cause overheating during the summer. On the other hand, the proposed facade design has an annual dynamic operation, shifting from sun-shading function during the cooling-dominated periods to double facade during the heating-dominated ones. The assessment is, therefore, in general greatly dependent on the reference points and what the objective focus in each situation is. Finally, to spark further discussion, a comparison of the reflective values of the current design's shading membranes with other applied UHI mitigation strategies aimed to evaluate the impact of the materiality of the proposed design to other common practices and to reflect on the possible benefits of each case. The examples chosen for this comparison were a standard white paint, an ultra-white one, cool-colored paints, and retro-reflective materials, because they are based on the principle of radiative cooling, which is a passive cooling technology that offers potential to reduce space cooling cost and tackle the UHI effect. Figure 29: Building’s energy and environmental performance comparative evaluation charts. From the above applications, retro-reflective materials can have a more targeted contribution to the UHI effect by avoiding the reflection towards the urban environment and, therefore, are a more competitive solution against the design of the current project. The question that followed then was to which extent of building applications and context this solution would be equally beneficial without increasing the complexity of the intervention. It can be assumed, for example, that in a fully opaque facade, the application of retro-reflective materials could be a more efficient solution, since it is simpler to apply, more time- and cost-efficient, and can achieve the same or even better results, since a PTFE membrane can achieve about 70% of solar reflection, whereas it can be easily replicated in many similar situations. In contrast, once the window-to-wall ratio starts increasing, then more parameters are intertwined, with the user's inner comfort having a more central role.