Kastro of Sifnos constitutes an appreciable settlement in the island for his locality, his history and his architecture. His geography and the land-planning organisation of residences in the settlement present particular interest and are results of his medieval history and consequent of the conditions of existence in the settlement those years.

 The architecture of settlement is interpreted through the needs of residents of season and it presents particular interest because it is maintained until today. In the research that follows, the history of island and his general characteristics were studied and then, with the research on the spot in the island, we collected elements for the history, the architecture, and the land planning of Kastro but also the residence in this. Also the categories of settlements, their manufacture and the daily life of residents were studied. The current residents helped us to comprehend the difficulties of that season and they put us up in their residences in order to see their situation and be informed for their way of manufacture.

 At the same time studying the climatic data of region, we wondered for the conditions of existence in the interior of residences and we followed an inquiring process with the help of design programs. Through the study of four residences that was selected, aim of this research was the investigation of their energy behavior.  In each building the morphology, the manufacture and the materials that were used, were examined and at the same time the social and economic elements that led to later interventions. The materials of manufacture of these residences were investigated with detail, aiming at their simulation in models, with the help of design programs. Importing all the essential elements about the manufacture of residence, place, orientation, we were informed for the required charges of heating and refrigeration of residences all the time but also for the levels of natural lighting in the interior.

 Aim of programs was to appreciate the effect that the different characteristics of form and place had, that had been applied in the each type of building, inthe internal microclimate that they developed. The residences that were studied were not manufactured obviously with base their energy output, as it becomes today, but potentially it was followed daily practical that come out through the experience. Consequently the results from the modelling of buildings were used for comparison between them and also in order to know their current needs, to function in conditions of comfort, with base the current data.

 The results, that were collected, helped in the export of conclusions on the daily existence in the settlement of Kastro the 18th century. At the same time the reduction of this results in the current data leads us to new conclusions and thoughts that concern the modern social needs and requirements of season. The modern need for ‘energy independent’ residences, released by no renewable sources of energy and that exploit the natural sources, is connected with the object of research, because the results lead to ascertainment which are capable of the achievement of this objective.