**3.3.1 Western orientation**

The environmental conditions throughout the week of measurements were characterised by predominantly clear skies (0/8), high air temperatures (mean maximum air temperature of 34.5 oC, mean minimum air temperature of 28.5 oC and mean air temperature of 31.3 oC).

### **3.3.1.a Natural stone products**

When facing towards the west, marble panels recorded mean maximum surface temperatures of 39.6 oC (Tair + 5.1 oC) for white marble and 58.1 oC (Tair + 23.6 oC) for dark grey marble. The mean surface temperatures of these materials were 31.6 oC (Tair + 0.3 oC) and 39.8 oC (Tair + 8.5 oC), respectively. It should be noted that at 20:00 (after sunset) the surface temperatures of all the samples except of the white one were over 35 oC, indicating that their temperatures were higher than the corresponding air temperature, by more than 5 oC.

All the west-facing granite panels, overheated during the afternoon, reaching mean maximum temperatures of 48.1oC that were well above 45 oC for the white-beige sample, 59.1 oC for the black one. The mean surface temperatures of the samples range from 35.5 oC (Tair + 4.2 oC) to 40.3 oC (Tair + 9 oC). Similar to the marble samples, the granite samples were, at 20:00, warmer than the air by 5 oC to 10 oC. It is noted that the dark-coloured granite surfaces, were warmer than the air by more than 15 oC.
