G r e e n R o o f s a s P a s s i v e C o o l i n g S t r a t e g i e s
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As it can be observed, the surface temperatures on the upper side of the substrate of the
green roof (MNV_GR) during the day are actually lower (up to 10°C) compared to the
external air temperature. On the contrary, the covering surface temperatures of the other
roofs are undoubtedly higher, with maximum temperature that arrives up to 80°C for
roofs with copper covering (MNV_LR, MV6_A) and go down to 50°C for ventilated clay
tiles roofs (LV3_A e LV6_A).
Fig. 7 shows temperatures on the soffit of the wooden slabs of the roofs on the same
day.
It can be seen how the differences between the temperatures are rather low in terms of
absolute value because of high insulation of the slabs. However, the green roof
(MNV_GR) is able to guarantee lower internal surface temperature which is also
considerably attenuated and delayed in time compared to the other roofs. In particular,
the difference in the surface temperature of the green roof was observed to be around
2.5°C compared to the temperature of the copper covering of the non-ventilated roof
(MNV_LR), while it went down to 2°C compared to the temperature of the other
ventilated roofs. Moreover, the average daily amplitude of the surface temperature for
the green roof was around 1.5°C-2°C, while for the other roofs it reached 3°C-3,5°C.
Figure 7: Temperatures on the soffit of the wooden slabs (roof types 1,2,3,4,7) with respect to the
external air temperature and the total radiation on 12th August
In order to highlight the passive cooling of the green roof, Fig. 8 shows heat fluxes
measured in the wooden slabs during the whole week considered. Positive values
represent heat gains, while negative values represent heat losses.
