## 3 Results
### Thermal Images of an Urban Canyon  
During all fieldwork days, facades and surface temperatures of the urban canyon were recorded using a FLIR thermal camera. The analysis of surface temperatures was done considering the predominant surface exposure. During summertime, the fieldwork was carried out on the 7 th July 2018, and the temperature of the facades was registered at 9 a.m., 1 p.m., 3 p.m. and 7 p.m. The analysis of the recorded temperatures in the south and north facades of the buildings showed that, between 9 a.m. and 3 a.m., the southern facade always presented temperatures higher than those registered in the north facade. The only exception occurred at 7 p.m. when the northern facade registered a maximum temperature slightly higher than that recorded on the south facade. Figure 8 shows the temperature of the southern facade at 3 p.m. when the highest temperature was recorded. The highest average temperature of the entire facade was also recorded at 3 p.m. Figure 9 shows the temperature of the north facade when the highest surface temperature was reached (7 p.m.). In the south facade, the highest average temperature throughout the facade was recorded at the same time the highest maximum air temperature was recorded. In the east facade, the highest surface temperatures were recorded between 1 p.m. (39.1 \({}^{\circ}\)C) and 3 p.m. (34.6 \({}^{\circ}\)C). Figure 10 shows the variation of the surface temperature of the east facade at 1 p.m. On the west facade (Figure 11  
The analysis of the thermal images collected in the east and west facades showed that, in the morning, the east facade presented higher temperatures than the west facade since it received direct solar radiation. In the afternoon, the opposite was observed, with the west facade presenting higher surface temperatures. However, by analyzing the differences between both facades, although the east facade received radiation during most of the morning period and the west facade only began receiving radiation after 1:40 p.m., ending shortly after 7 p.m., the temperatures reached by the latter were higher than those registered in the morning on the east facade. Regarding the influence of the exposure of facades, the ones south-exposed, always presented, both in the morning and in the afternoon period, the highest temperatures of the four facades studied. In springtime (in the morning), this facade presented higher temperatures, when compared to the north facade, on average (6 \({}^{\circ}\)C). The same happened, in the afternoon, when this facade was, on average, warmer than the north facade (4 \({}^{\circ}\)C). In the summer, the south facade was warmer than the north even when the latter was already receiving direct solar radiation. The results show that facade surface temperatures directly respond, most of the time, to the incidence of solar radiation. However, the maximum temperatures on these surfaces were sometimes recorded under conditions where the facades were no longer receiving solar radiation. This shows that even materials used in urban environments which only receive diffuse solar radiation have important thermal responses that can contribute to warming the urban environment. Figure 11: Summer thermal image of west facade (3 p.m) and corresponding histogram. Spot temperatures: Sp1 = 28.5 \({}^{\circ}\)C, Sp2 = 27.8 \({}^{\circ}\)C, Sp3 = 29.1 \({}^{\circ}\)C, Sp4 = 29.3 \({}^{\circ}\)C.  
Figure 10: Summer thermal image of east facade (1 p.m) and corresponding histogram. Spot temperatures: Sp1 = 25.1 \({}^{\circ}\)C, Sp2 = 32.1, Sp3 = 25.3 \({}^{\circ}\)C, Sp4 = 29.6 \({}^{\circ}\)C.  
Thermal Images of Other Urban Surfaces and Materials  
Thermal images of horizontal surfaces were also collected in two day and are representative of spring and summer periods. The differences found allowed us to see that asphalt is the type of material that presented the highest temperatures when compared to the temperatures registered by other materials.