Air Conditioning in the Middle Ages
How ancient architecture design principles inspired sustainable models for modern cities
The microclimate of the Arab-Norman architecture
The architecture principles and workforce they used are those of the Muslims they conquered. This particular Arab-Norman architecture only exists in Sicily. Among its most innovative characteristics, we can find an architectural technology geared toward an attention to climate. The Arab-Norman residencies were part of the "Sollazzi Regi" circuit, pavilions built in order to protect the sovereign and its court from the heat of Palermitan summers: cool and ventilation were among the principles of climatic technologies used by arabs. These ventilation system came approximately 850 years before the technological solutions adopted in modern buildings. They are an incredible example of a sustainable AC system using renewable energies.
The Zisa Castle
In the Arabic language, “aziz” means noble and powerful—and this is how the great Zisa building must have looked. The Zisa castle was built in 1164 by Norman governors. The natural ventilation of the Castle was made possible by many elements: first, the Zisa was erected as a large parallelepiped based on a perfectly symmetrical rectangular plan. In contemporary studies, the Zisa is defined as “a marvellous bio-climatique machine”, a “futuristic” example for the design of sustainable cities.
Palazzo della Zisa - dettaglio muqarnasYouth Committee of the Italian National Commission for UNESCO
The natural ventilation
The Zisa ventilation system came approximately 850 years before the technological solutions adopted in modern buildings. It is an incredible example of a sustainable AC system using renewable energies.
The natural ventilation inside the castle was achieved through five main elements: the large pool in the garden at the front, the fountain located on the ground floor, the two ventilating chimneys and large wet sheets hung beneath the ceilings of the various rooms on the upper floors.
Cooling down with the marine breeze
The Zisa was erected as a large parallelepiped based on a perfectly symmetrical rectangular plan. The main facade facing north-east, together with three large openings, allowed who was inside to enjoy the benefits of the sea breezes.Then, the breezes from the city’s harbour got cooled in passing over the pool. The air entered through the large entrance patio and underwent the chilling influence of the central fountain. While it began to heat up, the cool air flowed upstairs. This rising stream was further enhanced by the chimney walls which, heated from the outside by the sun-rays, produced many internal vortexes of air. These small vortexes somehow pushed up the cool air. Thus, the air circulated throughout all the rooms. The ventilation chimneys were housed in the two lateral towers of the building, and were connected to all its three storeys.
Palazzo della Zisa - Nicchia della sala principale con fontana e muqarnasYouth Committee of the Italian National Commission for UNESCO
The bioclimatic function
The remaining hot air was refrigerated using wet sheets hung beneath the ceilings of the rooms on the upper floors. There was also a large tank situated in front of the castle and collecting the water flowing from the internal fountain. These large volumes of water, besides hosting a large number of colourful fish and water plants, had a bioclimatic function.
Palazzo della ZisaYouth Committee of the Italian National Commission for UNESCO
Palazzo Della Cuba
This ventilation system was approximately 850 years ahead of the technological solutions adopted in today’s buildings, and it provides an incredible example for sustainable AC system using only sea breeze and water. So much so that we can talk of a highly energy efficient building ante-litteram. As much as the Zisa, the composition of the Cuba Palace was studied to create a constant flow of ventilation. Every aspect of the structure was conceived to reach the objective of fighting the heat: from the windows opening to the flow of water outside of the building. The Cuba was in the middle of an artificial lake 2 meters and a half deep. The inside was built with three aligned environments: at the center of the main square there are remains of a fountain built here for the refreshment of the air. The thick walls and the few openings were used for climatic purposes,
Palazzo Cuba - le muraYouth Committee of the Italian National Commission for UNESCO
Palazzo Cuba - dettaglio della volta ogivaleYouth Committee of the Italian National Commission for UNESCO
Sustainable comfort
Passive cooling is a contemporary building design approach that focuses on heat gain control and heat dissipation in a building, used to improve the indoor thermal comfort with low or nil energy consumption.
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Bioclimatic planning
Bioclimatic architecture, a new frontier of design, uses natural elements (water, wind, sun) in order to realize energy-efficient and non-polluting buildings. The cubic shape is the option of choice to maximize the interaction with the environment.
The principles of this new tendency were used 850 years ago. These buildings, for their extraordinary ventilation system, play a key role in many contemporary studies and they are a reference example for bioclimatic designers in many countries such as Singapore (Museum of Art and Science), Poland, Saudi Arabia and Canada.
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