**3.3.1.b Ceramic products**

434 Solar Radiation

The metal products involved were grey-coloured composite aluminium panels. In the case of east-facing panels, the maximum surface temperature recorded was 49.5 oC, but for the west-facing ones, it was 45 oC. The temperature, T19:30 of the panels was higher than the

The vegetal surface was a reinforced concrete wall covered with Virginia creeper (Parthenocissus spp). Its temperatures remained lower than the air temperatures throughout

The PV panels used were blue-coloured poly-crystalline ones. These were integrated into a south-facing, ventilated PV façade. Their mean surface temperature was lower than the mean air temperature, while their absolute maximum temperature reached 44 oC. It is important to note that, around sunset, the PV panels were cooler than the air by 4.2 oC. These findings are considered very important because they show that during the summer period, southern facades clad with PV panels do not affect thermally the microclimate, while

The results of the experimental measurements are presented in Table 4 for the western

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

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

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

**3.2.4 Metal products** 

**3.2.5 Vegetal surfaces** 

the day.

respective air temperature by 3 oC.

**3.2.6 Photovoltaic (PV) panels** 

**3.3.1 Western orientation** 

**3.3.1.a Natural stone products** 

31.3 oC).

5 oC.

contributing to the use of renewable energy.

orientation and in Table 5 for the southern orientation.

**3.3 Results of the experimental measurements of facade materials** 

Thin ceramic panels and tiles that face towards the west recorded maximum surface temperatures, which may range from 44 oC (for white) to 56.6 oC (for black) and are from 9.5 oC to 22.1 oC higher than the mean maximum air temperature. The mean surface temperature of the white sample is 33.6 oC (Tair + 2.3 oC) and of the black sample 38.8 oC (Tair + 7.5 oC). The mean surface temperatures of the rest of the samples are 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 between 30 oC and 35 oC, i.e., no more than 5 oC higher than the corresponding air temperature.

Ceramic panels of increased thickness (13 mm) recorded surface temperatures similar to the thin ceramic tiles and panels with similar colours. The white-coloured sample has a mean maximum temperature of 44.1 oC (Tair + 9.6 oC) and a mean temperature of 33.8 oC (Tair + 2.5 oC), while the brown-coloured one has mean maximum temperature of 52 oC (Tair + 17.5 oC) and a mean temperature of 37.4 oC (Tair + 6.1 oC).

### **3.3.1.c Wooden products**

West-facing composite wood panels recorded very high surface temperatures. The lightcoloured and the intermediate samples reached a maximum temperature of about 52 oC, while the dark-coloured one had a mean maximum temperature of 59.6 oC, which was 25 oC higher than the mean maximum air temperature. Concerning the mean surface temperatures, the samples were warmer than the air by 6 oC to 9.4 oC. After the sunset, the surface temperatures of all three samples were close to the air temperature.



Table 4. Overview of the experimental measurements on samples of building materials facing West.

#### **3.3.1.d Metal products**

When facing towards the west, even light-coloured composite aluminium panels (white colour) recorded surface temperatures, which were higher than the corresponding air temperature by more than 10 oC. For the range of colours, mean maximum temperatures were 10 oC (for white colour) to 31.8 oC (for black colour) higher than the mean maximum air temperature. Mean surface temperatures range from 33.7 oC for white to 42.4 oC for black panels, and are thus 2.4 oC to 11.1 oC higher than the mean air temperature. Finally, the surface temperatures at 20:00 (after the sunset) are between 30 oC and 35 oC and are no more than 5 oC higher than the air temperature at that time.

The mean maximum surface temperatures of west-facing samples of different metal sheets had a temperature range from 40.1 oC (titanium) to 49.5 oC (quartz zinc, dark grey natural). Their mean surface temperatures ranged from 31.9 oC (polished zinc) to 36.8 oC (quartz zinc, dark grey natural), and were higher than the respective air temperature by 0.6 oC to 5.5 oC.
