Z E M C H 2 0 1 2 I n t e r n a t i o n a l C o n f e r e n c e
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Conclusions
The research shows results of an experiment carried out to evaluate the thermal
performance of a green roof under temperate climate and to compare it with other types
of roofs. All of them were installed on a highly insulated building according to present
national regulations on energy efficiency and savings.
Results highlights that in summer, installation of a green roof leads to lowering of surface
temperatures and their daily amplitude. This phenomenon takes place both on the upper
part of the soil substrate where, even on hottest days, temperatures turn out to be lower
than those of the external air, thanks to the shade and evapotranspirative phenomena of
the vegetal layer, and also on the roof soffit because of the thermal mass made up of the
soil substrate.
As regards the thermal fluxes, in terms of absolute value, they do not turn out to be very
different from those of the other roofs because of low transmittance of the systems.
The passive cooling effect of the green roof, in part inhibited by high insulation, is
nonetheless accentuated by the presence of fluxes going out of the slab 40% of the time
during the summer season considered and by significant thermal delay of incoming heat
flux waves.
From the results, it follows that with adequate calculation standards for assessing
thermal transmittance, green roofs could have a more widespread use especially in
retrofitting existing buildings where roof systems have higher thermal transmittance.
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