## 3 Results  
### UHI Direct Impact Evaluation--Outdoor Microclimate Studies  
The results from the cumulative irradiance maps can be seen in the overview in Figure 17, where with highly absorbent surfaces there was negligible impact between the facade types, since most of the radiation is absorbed and is irrelevant to the facade geometry. This case, however, would lead to undesired effects on the overheating of the building's interior and, thus, increasing the resulting indirect impact. On the other hand, when reflective surfaces were involved, the proposed design's impact was slightly more apparent, but still showed a mere 3% reduction of the total radiation. Perhaps more important was that the radiation was reduced mostly near the facade surface, avoiding unpleasant comfort situations for pedestrians walking nearby. A further aspect concerns also the impact of the facade surface temperature on the UHI effect and the relation between the different surface types, window-to-wall ratios, and cumulative irradiance on the urban environment.  
Figure 16: Overview of the input parameters and boundary conditions for the SimScale CFD convective heat transfer analysis in the summer situation.  
The results in Figure 18, which were targeted more on the reflected part of the total radiation, showed that the percentage of the cumulative radiation that is responsible for the reflected radiation from the facade and the surrounding surfaces was reduced by around 40% with the proposed design, with again a reduced radiation close to the facade surface. However, that portion still accounted for only 6% of the total radiation, which is a relatively small amount and, therefore, would lead to the conclusion that even though the direct impact could be minimized with the proposed facade geometry to reduce the overheating of the urban microclimate, the overall impact in this regard is not significantly large.  
Figure 17: Cumulative radiation values on street level in an Athens urban canyon (cumulative radiation: direct, diffuse, and reflected radiation from all the surrounding surfaces).  
The results from the comparative sun ray trace analyses can be seen in Figure 19. In accordance with the radiation analysis grid results, the ray trace analyses showed that a typical facade reflected the sun rays downwards towards the street level, if no other obstacles were obstructing the rays' direction. On the contrary, the proposed design reflected most of the sun rays upwards back to the atmosphere. In addition to this, the small number of rays which did not fall in that category and deviated by bouncing more horizontally due to the reflection on the different angles of the geometry surfaces, still did not bounce towards the street level, but to a much higher level above the ground. They were also scattered throughout the opposite building's length and height thanks to the convex outer geometries, avoiding undesired and increased solar focus points, as well as concentrated heat areas in the surrounding urban environment.  
Figure 18: Analysis and partial values of the total cumulative radiation on street level in an Athens urban canyon (cumulative radiation: direct, diffuse, and reflected radiation from all the surrounding surfaces).