Bioclimatic behavior of the ‘casas payesas’ and its improvement.
<< The harmony and strength of Ibiza can only be perpetuated if the vocabulary of the forms that give it character find its contemporary equivalent. It is not a matter of imitating the architecture of the past, constructing incongruous decorations that do not correspond to our times or our needs, because what impresses personality to Ibiza, what makes it be as it is, is neither more nor less an architecture of limitations solved with great simplicity of forms. Also, introducing elements of popular architecture imported from other regions, will destroy the harmony and unity that have survived the passing of centuries. There is therefore a continous and constant discipline of limitation to authentic forms if Ibiza is to remain what it is: something unique. >> From Ibiza, strong and bright. J.L. SertCONTEXT The current situation, the crisis, the climate change, the excess of energy consumption, etc. All these reasons force the current architecture to adapt, to reinvent itself, and to comply with the demands of the current panorama. In Ibiza, as Sert explains, the adaptation of the architecture to one of less energy demand, has to take into account the personality of the island. It is important to integrate bioclimatic strategies to update the architecture of Ibiza and at the same time to maintain its essence. Improving the energy efficiency of existing buildings and saving energy through energy rehabilitation and the construction of new nearly zero-energy buildings (NZEB) is a key objective for the EU Member States and the European Commission because it reduces energy consumption, and therefore CO2 emissions and climate change, is more energy independent and helps create jobs. ANALYSIS OF THE CLIMATE AND THE CASA PAYESA From a smaller scale, the aim is to analyze the energetic rehabilitation of the ‘casas payesas’ (literally peasant houses), since these are designed for a family life typical of the nineteenth century. Most of the traditional houses on the island require, for their bioclimatic properties, the installation of heating systems, and in some cases of cooling, depending on their location. The ‘casas payesas’ have a very good energy performance in summer. This is due to the few holes in the facade and the thick walls, which gives the building a high thermal inertia. In winter, however, traditional Ibizan houses are cold, forcing them to install active heating systems. Throughout the winter temperatures range from 16 to 20ºC, while in summer they do not exceed 23ºC. These houses were designed to be inhabited by people who belonged to the nineteenth century, times when the demands of comfort, activities carried out inside the house, and even the clothes were different. It is necessary to adapt the ‘casas payesas’ to the demands of today. Can Jai. Ibiza The climate of the island of Ibiza is temperate, due to the mild contrasts of summer-winter and day-night temperatures. Relative humidity, which increases by the proximity of the sea, gives the climate of the island a smooth continuity throughout the year. Due to the latitude the radiation is high. The skies are never completely clear despite the low level of cloudiness, due to the high humidity of the environment, but even so, the latitude in which Ibiza is located allows us to take advantage of the high solar radiation throughout the year, avoiding a high energy consumption from non-renewable sources. The difficulty of solving the problems of comfort derived from this climate is maximum because total comfort is inexistent in both dominant seasons. STRATEGIES Collecting heat during the daytime and storing it to be used in the coldest hours are the most important strategies to obtain optimum comfort level in winter. For the warmer months, due to the high humidity of the environment, continuous natural ventilation, both day and night, is essential. Solar protections and their ability to adapt to the different seasons are essential to prevent direct solar radiation in summer while allowing light and heat in during the winter. The floor that is in contact with the ground is the house’s regulating element. Its high transmittance cools the inside spaces throughout the year. This favours indoor conditions in summer, but not in winter. An insulated double wall is the solution to this problem, since it controls the flow of the cold air, keeping it out in winter and drawing it in in summer to cool the house and to increase the ventilation. Incorporating greater surfaces of glass in the facade and skylights in the roof will increase solar collection and interior luminous comfort, throughout the year. We can therefore achieve a significant reduction in energy demand by integrating passive bioclimatic systems. The traditional architecture would maintain its aesthetics unaltered while significantly reducing energy costs. FRAN VÁZQUEZ. ARCHITECT.