Urban fabric performance in Mediterranean city : a typology based mass-energy analysis

Abstract

The link between urban form and building energy demand is a complex balance of morphological, constructive, utilization and climatic factor. Especially in European compact city where existing areas prevail on much more energy-efficient new settlements, it is evident that operative ways to transform efficiently the building stock have to be found. Moreover, it is now widely accepted that urban scale has a first rate importance in the building design process and its correlated energy performance. It has been observed that scaling laws are useful in describing the complex structure of urban systems: modern cities have a “metabòlic rate” that approximately follows the living organism scaling laws. Nevertheless, it has not been entirely verified that this connection remains the same while studying the phenomena at the urban and building scale and what kind of relationship between mass and power exists (i.e. energy) depending on typologies and urban form. This study suggests an approach for using mass parameter - representative of built-form - as energy performance evaluation tools on a homogeneous urban texture. Mass is connected to both built-form and technology and these determine, to a great extent, the energy use. In Mediterranean climate, it has been observed that mass has strong relevance on energy demand playing an important role in reducing heating and cooling consumptions. Our work aims at validating this relationship, focusing on widespread urban fabrics of the Mediterranean compact city. Tests on diferent case studies from Barcelona and Rome (analyzed independently in terms of their energy demands and their masses) are carried out. Mass evaluation is based on calculation of effective mass of built elements. Building energy demand is assessed by modelling on multi space dynamic thermal analysis tool. Results presented and discussed point out that heating and cooling energy demand are related to urban fabrics mass and, starting from typological based analysis, it’s possible to estimate it. This work is a broader treatment of a research study about one possible way to comprehend “metabolic rate” scaling law concerning urban fabric. Such knowledge-base could giving hints to conscious and effective built environament transformations towards more efficient conditions.