**3.3.2.a Natural stone products**

South-facing marble panels measured lower surface temperatures than west-facing ones. The mean maximum temperature of the white sample was equal to 36.7 oC (Tair + 2 oC), which is 3 oC lower than respective temperature of the west-facing one. Similarly, the mean maximum temperature of the dark grey sample was 51.7 oC (Tair + 17 oC), and 6.6 oC lower than the temperature of the one facing west. The mean surface temperatures of both samples were almost equal to those measured for the western orientation, namely 31.1 oC (Tair - 0.1 oC) and 39.7 oC (Tair + 8.5 oC), respectively. The surface temperatures of the rest of the samples fall between the above-mentioned extremes.

When granite panels have a southern orientation (Figure 23), their surface temperatures are lower compared to those measured when they faced towards the west. The mean maximum temperatures of all the five south facing samples were 6 oC to 9 oC lower than the "western" ones. The white-beige sample had a mean maximum temperature of 39.3 oC (Tair + 4.6 oC), while the grey-coloured samples had 50.3 oC (Tair + 15.6 oC). Contrary to the marble and the granite samples with southern orientation had lower mean surface temperatures than those of western orientation. The mean surface temperatures of the samples range from 32.8 oC (Tair + 1.6 oC) to 38.3 oC (Tair + 7.1 oC). The marble and the granite samples, when placed facing south, gradually cool down during the afternoon. As a result, their surface temperatures after the sunset (20:00) are close to the corresponding air temperature, surpassing it by only 1 oC to 2 oC.

### **3.3.2.b Ceramic products**

Thin ceramic panels and tiles that face towards the south recorded maximum surface temperatures, which may range from 38.1 oC (for white) to 50.5 oC (for black) and are from 3.4 oC to 15.8 oC higher than the mean maximum air temperature. The mean maximum temperatures of all the samples were approximately 6 oC to 7 oC lower than the mean maximum values, which were measured when the materials had a western orientation. The mean surface temperature of the white sample is 31.6 oC (Tair + 0.4 oC) and of the black sample 37 oC (Tair + 5.8 oC). The mean surface temperatures of the rest of the samples lie between the above-mentioned limits. Finally, the surface temperatures of all the samples of thin ceramic tiles and panels after the sunset (at 20:00) were close to the corresponding air temperature.

South-facing ceramic panels of thickness 13 mm recorded similar surface temperatures to that of the thin ceramic tiles and panels with similar colours. The white-coloured sample had a mean maximum temperature of 39.7 oC (Tair + 5 oC) and a mean temperature of 32.6 oC (Tair + 1.4 oC), while the brown-coloured one has mean maximum temperature of 48.9 oC (Tair + 14.2 oC) and a mean temperature of 37 oC (Tair + 5.8 oC). Compared to the temperatures, which were measured when the samples were facing west, the abovementioned surface temperatures are considerably lower.

#### **3.3.2.c Wooden products**

The surface temperatures of the composite wood panels with southern orientation were not very high. The light-coloured and the intermediate sample reached a maximum temperature of about 42.3 oC, while the dark-coloured one had a mean maximum temperature of 47.6 oC, which was 12.9 oC higher than the mean maximum air temperature. Concerning the mean surface temperatures, the samples were warmer than the air by 2.6 oC to 5.1 oC. A quick comparison with the temperatures measured for the western orientation reveals that the mean maximum temperature of the light-coloured sample is lower by about 10 oC, while that of the dark-coloured one by about 12 oC. Concerning the mean surface temperatures, the differences between the "western" and the "southern" surface temperatures range between 2.4 oC for the light-coloured sample and 4.3 oC for the dark-coloured one. Again, the observed differences due to the change of orientation are significant.

#### **3.3.2.d Metal products**

When facing towards the south, light-coloured composite aluminium panels (white colour) recorded low surface temperatures, but higher than the corresponding air temperature by only 2.6 oC. For the range of colours, mean maximum temperatures ranged from 2.6 oC (for white colour) to 16.5 oC (for black colour) higher than the mean maximum air temperature. The differences with the measured mean maximum temperatures of the western orientation are impressive and range from 7.4 oC, for the white colour, to 15.3 oC, for black colour. Mean surface temperatures ranged from 31.5 oC for white to 38.7 oC for black panels, and are thus 0 oC to 7 oC higher than the mean air temperature. The differences between the "western" and the "southern" mean surface temperatures of the two extreme colours (white and black) are 2.7 oC and 4.1 oC, respectively. Finally, the surface temperatures at 20:00 (after the sunset) are below 5 oC than that of the air temperature at that time.



Table 5. Overview of the experimental measurements on samples of building materials facing South.
