The effect of Water on passive cooling systems in the Arab-Norman architecture of the Zisa Palace in Palermo

This paper shows the theories argued by some historians with reference to the working of natural water passive cooling systems employed in the Zisa Complex. Albeit such theories are seminal attempts to understand passive water systems, they have no scientific evidence. This study instead concentrates on a more rigorous treatment that enabled to set up a robust framework for designing a historical water passive system such as the Salsabil, which in fact was conceived and developed in an empirical way. Several historical buildings of the Mediterranean and Middle Eastern architecture include relevant artefacts useful to control humidity and temperature through water passive systems . The architecture of Mediterranean Basin area is particularly rich of these examples, in which the weather requires a mitigation of its effects to improve the indoor living conditions[1]. Many representative ancient monuments apply inside them systems and techniques for passive cooling, such as a room [2] equipped with a water basin or a fountain, often located in the central position of the house, and therefore with an important symbolic meaning for social life. An outstanding water systems is found in Zisa Palace in Palermo, locally referred to as Castello della Zisa, which was built in 1160 by Arabian craftsmen. It incorporates includes a system of evaporative cooling and natural ventilation that guarantees satisfactory comfort even nowadays. The building develops around a square room which is the core of the structure, located at Ground Level. It is named "Sala della Fontana" and constitutes the main hall within the building for its stone Salsabil. With its considerable headroom, the rich wall decorations and the presence of water, this room, is a distinctive feature of the Islamic legacy. The research presented here aims to show the relationship between water supply and Castello della Zisa in Palermo. The design methods used by Arabian craftsmen in the development of hydraulic systems are explained and the techniques used by ancient Arabian designers to control water systems inside historical buildings are described. Throughout an advanced Computational Fluid Dynamic (CFD) model