Urban microclimate. Natural ventilation and open space in the historic city. Summary of critical evaluation on the italian and international research.

Analysing the city as a ‘relations system’, a reality, paraphrasing Edgar Morin, not only physical but also geo-psycho-bio-human in which humans must relate the manifestation of their own necessities and freedoms to the responsibilities related to them, one wonders what are the system inputs and outputs that determine the processes and changes, conditions of comfort and discomfort - starting from a necessarily interscalar evaluation - of the city as a complex 'urban room'. The difficulties concerning the ability to evaluate a multitude of contributing factors and the translation of these values into useful information on a practical level for crisis situations improvement (bearing in mind that knowledge of the factors, specifically the ventilation) vary, depending on the scale of the investigation and on the level of detail to achieve. The natural ventilation is one of these factors that is often not calculated for its complexity and inconstancy; instead, natural ventilation results in positive effects on the extent of the heat island which differs in relation to the wind speed and the characteristics of the building’s fabric. Remote sensing techniques and cartographic photointerpretation, according to Gis logic, computational simulation, the use of scale or empirical models or the realization of in situ measuring campaigns allows us to acquire data at various scales. Nevertheless, it is necessary to apply simplifications and-or limitations of the investigation field, both deriving from instrumental or functional requirements, especially by relating to complex fabrics such as those historic. This begs the question: how much said simplifications influence the responsiveness of the model to the real data? For this reason, part of my research has focused on the critical reading of professional literatures, interpreting some of the most important definitions with a wide design approach and considering what are the inputs and outputs of which knowledge is essential to locate a 'correct model' of air circulation, as synergistic product among various contributing factors. The main goal is to define a methodological analysis that aims to systematize the positive elements and minimize the problems of these methodologies, providing an expeditious support tool, that helps in the context analysis and in the definition of the first project phase, in view of a microclimatic improvement of the open space and even indirectly of the indoor ones of the ‘città storica’ for an 'integrated conservation’.