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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During the three hottest hours of the day, the climatic conditions remain substantially
unchanged (Fig.15-16).The
Salsabil
and the channels on the lateral foreparts are
ineffective for the purposes of the building climate control: the particles of water sprayed
from the
Salsabil
produce an evaporative cooling which relates a very small volume of
air, high only a few centimeters, that is not sufficient to cool the entire air volume of the
Fountain Room. The effects of the natural ventilation are prevalent and generate an
overpressure which drives these particles towards the bottom wall of the room (Fig.16).
Furthermore, there is no extraction of fresh air present in the central locals by the laterals
channels, because of the reduced section (120x20cm) and because of the excessive
drop pressure through the openings, transmit at higher levels only the hot air
accumulated near the inlet section (Fig.13), even when there is an excess of pressure
caused by sea breeze (Fig.15).
Conclusions
The analysis of the results obtained from simulations on the Zisa Complex shows the
thermodynamic behaviour influenced by the room position and the wall stratigraphy
finalized to indoor control, as it’s possible to see in many old buildings.
It has been observed that most of the elements present in the Zisa complex respond to
the functions assigned to them in literature, and some of the hypothesized phenomenon
have been verified by the results (building orientation, activation of natural ventilation,
the presence of thermal mass, etc.).
The assumptions that consider fundamental, for the purpose of thermal comfort, the air
movement inside the building for thermal gradient or pressure gradient and the control of
the solar radiation effects, have been substantiated by the obtained results.
In the more stately parts of the building, in fact, there are always good thermal conditions
during the day, especially in the vestibule and in the central rooms. For this reason the
devices particularly effective are the arrangement of internal and external windows, the
three openings in the roof, the considerable thickness of the building envelope, the
north-south orientation and the eastern large openings of the portico that allow to
capture the sea breeze.
The presence of
Salsabil
doesn’t provide a positive contribution to climate comfort. This
presence is probably only to satisfy decorative requirements, even if it could generate
positive psychological effects, as it’s often been observed in old buildings.
It is evident that the channels in the foreparts can’t be used as "ventilation pipes" or as
"wind towers". They are not able to catch the prevailing winds and to pipe them into the
room, also because of their shape, since the sensors are not present and the channel is
unique.
Notes
1. Art historic and professor at Palermo University. Particularly skilled in Norman art
and architecture.
2. Professor of technical systems and thermo-fluid dynamic measurements at Palermo
University.
3. German researcher on medieval architecture, in 1991 she made specific studies and
surveys on Zisa palace of Palermo.
References
AA.VV., 1979, "La progettazione dell'architettura bioclimatica. Atti del seminario sui
sistemi passive”, Bari, Franco Muzzio & Co. Editore;
