Densità sostenibile: forma, ambiente costruito, energia

This research aims at exploring meaning, quality and analytical capacity of density concept and its potential interpretations in architecture and sustainability fields. Its goal is to determine the relationships among built environment, energy and form of urban textures in Mediterranean compact city, taken density as useful parameter to illustrate their features. Despite the growing unsustainability of today’s city facing an effective energy and environmental crisis, recent statistics have confirmed the increasing attractive power of metropolitan areas. Within the context of European compact city, new building models, based on energy conservation, account for an insignificant percentage compared to existing city whose functioning remarkably affects the efficiency of the whole metropolitan system. Therefore, an approach determining instruments and design methods at both urban and architectural scale, should be found in order to set out conditions more appropriate to the compact city. In respect of this kind of scale, the relationship between energy and form takes a central role in the variation of energy performances; at the same time the concept of density has showed itself as an efficient instrument of analysis of the morphological performances of the built form. This research is composed by five interconnected parts. The first one examines urban and energy dynamics’ current conditions to comprehend the role and contribution of the building industry considering the scientific progress and the implementation of present operational instruments. The second one investigates role and evolution of the density concept as parameter, design instrument and basis of theoretical categories, especially referring to interactions with urban form and sustainability. In the third part the analytical abilities of density are employed to prove the environmental implications and verify the existence of interactions among urban sustainability indicators and density. Then, the fourth one enquires into the relationships among density and energy at the urban scale. Finally, the fifth part investigates such relationships in the compact fabrics in Rome and Barcelona by models and simulations set up in order to control the correspondent factors. The influence of urban morphology, built-form and constructive features on solar access and energy demand for heating and cooling is shown by different definitions of density indicators. Among these, are determined those more suitable to express reliable trends in relation with solar access and energy demand. Firstly results point out that the contribution of the built environment to the complex energy issue arisen by metropolitan systems must be focused on the reduction of the demand - even before on the consumption and impact - operating with multi-scale methods and instruments for the transformation of existing city. Density has a preferred role in the relationship between sustainability and form, thanks to its interpretative skills and meanings undertaken as theoretical and design category. At the metropolitan scale, urban sustainability indicators and density do not always show evident relationships with energy and environmental implications. Built-form, typology and constructive features are the main factors that occur on energy performances variation of urban fabrics. The investigation of these kinds of performances by density parameters permit the comprehension of the different energy behaviors in each urban texture, offering a contribution to the instruments of energy analysis at urban scale and permitting more efficient conditions for the built environment leading to the concept of sustainable density. Methodological structure and the determined parametrical instruments show themselves as knowledge base for aware transformations of Mediterranean compact city