The hours with an operative temperature higher than 28 ◦C in
Cairo are reduced to 48% and 64% respect to ST when applying
CR, for the insulated and not insulated configurations. Reductions
around 10% and 28% are calculated for respectively CR low-e and
GR. The number of hours with operative temperatures higher than
30 ◦C is significant in Cairo and the passive techniques can improve
the indoor comfort conditions. The number of hours is strongly
reduced using cool roofs (between 18% and 34% respect to ST),
while GR reduce to the half that numbers. Moderate advantage
is achieved with the metallic cool roof, with a number of hours
reducing between 66% and 75%.