The number hours with operative temperature higher than 28 ◦C
are reduced of 73% and 82% respect to ST for CR applications in
Palermo; this happens for the insulated and not insulated configurations.
The low emittance cool roof reduces of about the 20%
the hours above 28 ◦C, while the reduction increases to about 28%
for the green roof. The three roofing systems reduce to negligible
numbers the hours above 30 ◦C.