Transformation process and induced comfort in the Ottoman houses

The old town of Algiers, known as the Casbah, is the product and the place of social relations, but also of cultural models impregnated with history and intrinsic immaterial qualities. It is the manifestation of a superposition of several strata in a complex and original system; it is the trace of successive occupations, the collective memory which preserves and transmits the adopted or rehabilitated cultures to its ways of life. In other words, it is a living whole that has withstood the wear and tear of time. Algeria has a rich heritage, not only as a historical value and identity, but also for the different solutions used to meet the environmental requirements and more precisely the needs of comfort. The Casbah of Algiers is an eminent example of a traditional human habitat, representative of the deeply Mediterranean culture, synthesis of numerous stratifications. It composed of the most interesting houses, which have retained their authenticity and integrity, such as the aesthetic characteristics, the materials used and the architectural elements, retaining their original aspects and expressing values that gave it a place in World Heritage in 1992. They have an old architecture that remains impressive and represents aspects of traditional vernacular architecture, illustrated as an example of a perfect harmony in the built environment with the natural environment, allowing a quality of comfort, ensuring a healthy and comfortable indoor environment. During the colonial and postcolonial periods, it is clear that the houses of the Casbah of Algiers had a process of transformation/modification that is still undergoing, due to the will of the inhabitants to rise to the standards of modernity. These same transformations have certainly manifested themselves according to the needs, but often at the expense of the environment. They are the result of the overlap and juxtaposition of architectural models (local and colonial ones): each way of life reflects a historical period and a population that is constantly changing. This paper focuses mainly on the nature of transformations endured by the residential building of the old Ottoman Algiers until now and analyses their impact on thermo-hygrometric comfort and indoor microclimate. Our reflection is linked to concepts with multidisciplinary dimensions that flicker between history, architecture, town planning, geography, socio-cultural, hydraulics and environment. In fact, the environmental issue is becoming more and more dominant in the new orientations and concerns related to the improvement of comfort conditions. Therefore, the applied methodology is based on two approaches: a historical one, aiming to identify the architectural changes into old Ottoman houses, transforming the space and the openings (patio or chebâk roofing “it is a house with a courtyard that is either covered with a fence called chebâk, or discovered called patio”, close off openings, ventilation, new openings, kitchens and bathrooms renovation, heating plant system, etc.), and an environmental one in order to measure the effect of these transformations on the thermo-hygrometric comfort. These practices have generated sometimes small or even enormous disorders, which have brought changes also in the indoor comfort. Archives consultation, field investigations, modeling and numerical simulations will be essential tools, which will allow us to achieve the expected results. A detailed corpus, considering the least transformed houses to the most transformed ones, will be presented, accompanied by an accurate evaluation of the parameters influencing the thermo-hygrometric comfort.