THE “ZISA” IN PALERMO: BIOCLIMATIC ASPECTS OF ITS ARCHITECTURE

In the present work is examined, as an ante-litteram example of summer residence and bioclimatic archi-tecture, the ancient castle of the Zisa (from the Arabic 'al-aziz = noble, shining, glorious), meaningful work of Arab-Islamic character built up at the beginnings of the XII century (fig. 1). The building holds a notable importance as it is one of the few examples of Norman civil architecture with elements of Arab-Islamic character and Byzantian culture, but also because it had been conceived according to the most re-fined Islamic techniques of free cooling. The building (fig. 1) presents itself like a massive rectangular construction developed on three levels. On the architectural plan the monument has been object, in the past and today, of numerous studies of ar-chaeologists and historians of art, also in order to enucleate the numerous superfetations that have been there superimposed on it during the centuries. The original shape and of the building is documented by the help of the data observed during the repairs made in recent years and by the description of the domini-can monk Leandro Alberti (1526). It had little or no maintenance up to 1635 when was granted, charge free, to Giovanni de Sandoval[2[13]] who introduced modification that stopped the state of ruin but deeply altered the image and the original structure of the construction. He added, among other things, a new building body on the coverage storey, back set respect to the façade, which completely covered and shut up the tree original open atria set at the second floor. In the 1809 the Zisa passed to the prince of Sciara, Francesco Notarbartolo, who maintained the possession up to 1951, and then it was assigned to State property (Regional property). The first recent works of repair began in 1952; they were interrupted in 1958 and restarted in 1966, but again paralysed in the same year. On October 13th 1971 collapsed a big part of the north wing, where the transformations made in the 17th century by Sandoval had weakened the reactions of perimetral walls to the thrust of the vaults and of the principal arches. The project of the re-pairs was committed to Arch. Prof. Giuseppe Caronia [3] who had to solve the important dilemma: to re-construct the collapsed parts so reconfiguring the original spatiality or to limit oneself only to consolidate the surviving parts. Prevailed the decision to reconstruct the monument restoring the ancient original vol-umes but preserving some elements of the repairs operated in the 17th century. The aspects connected to the bioclimatic function of the building have prevailingly been object of “intui-tions” deprived, up today, of any specific verification. With the present work the authors introduce the results of a study on these bioclimatic functions of the Zisa. Particularly on the concrete possibilities of-fered to the building to use at the best the summer breezes coming up from the sea. On the basis of a more careful examination of the morphological characters of the monument and of the meteorological data col-lected at D.E.A.F., in the summer season of the current year, it is finally analysed and interpreted the function of two tower bodies existing on the small and opposite fronts of the building to which the knowledge has attributed, up today, the function of “towers of ventilation”. The results of the analysis of the authors make inconsistent such hypothesis and lead to a different interpretation, already advanced from isolated researchers: they were “chimney ducts” for fireplaces.