## 2 Materials and Methods
### UHI Direct Impact Evaluation
#### 2.2.2 Outdoor Microclimate Studies--Urban Level  
Cumulative Irradiance Heat Maps  
Following the component level, the stage of evaluation of the direct UHI impact on the urban level involved the simulation and visualization of the cumulative irradiance on the urban environment, assuming the scenario of an urban street canyon in Athens with the proposed south-oriented facade design. The most important part of this study laid on quantifying the reflected part of the solar energy and assessing the effect of the facade geometry on its reduction on the street level and the neighboring buildings, in comparison to a typical facade surface, different surface types, and window-to-wall ratios.  
For this study, two approaches were followed, in accordance with the design tool's possibilities. In the first case, the Honeybee Daylight Analysis component was used to calculate the cumulative irradiance on the street level, which accounts for direct, diffuse, horizontal infrared, and reflected solar radiation from the surrounding surfaces. In this case, it was also possible to include information of the surface types, ranging from fully absorbent (R:0, G:0, B:0) to fully reflective ones (R:1, G:1, B:1), and the glazing ratio, comparing a fully opaque (0%) to a curtain wall (85%). However, it was not possible at this early design stage to insert and consider more detailed material inputs and properties. The analysis was conducted for the extremely hot week (03-09/08) as the worst-case scenario.  
However, even though the first methodological approach provided an indication of the cumulative radiation on the street level, the distinction between the different types of radiation and the contribution of the reflected part was not entirely clear. For a more comprehensive understanding, a complementary approach was followed, using the Ladybug Radiation Analysis component this time. The difference in this case was that the radiation accounts only for the direct and diffuse radiation (the infrared radiation is included by default in both cases). By decoupling these two analyses, it could then be possible to extract the value of the reflected radiation and compare the results, allowing for small divergence in the values due to possible slight differences in the two calculation processes. The flowcharts of the workflow for these two approaches are illustrated in Figure 9.  
Comparative Sun Ray Trace Analyses  
Lastly, a final validation check on the direct environmental impact of the facade was conducted in relation to the direction of the reflected sun rays as a full building facade and not as an isolated component or segment, and in the context of the urban street canyon with surrounding buildings opposite to the analyzed one. Since the facade is south-oriented,  
Figure 9: Flowchart of the two workflow approaches for the radiation analysis study and the design tools used for each case.  
the study concerned only the rays reflected from the proposed facade to the surroundings and not from the opposite-facing building. The analysis considered the date of 21 June between 12:00-13:00, when the sun is at its highest peak, and the comparison was then realized between the current design and a typical flat facade.