No abstract

The city, interpreted as a complex dynamic system, is experiencing ungovernable levels of entropic growth related to locally-based human activities. Indeed, the main antagonist of urban sustainability is anthropogenic entropy. The general crisis is due to the production of entropy within single urban subsystems, which is transmitted, with a ripple effect, to all the others and to the entire city. Due to endogenous malfunctioning in its parts or in its structure, a subsystem can be viewed as an "entropic generator" and can trigger a chain of damage that can lead to the collapse of the entire urban system. The urban crisis can thus be linked to the entropy produced, especially within the human subsystem. In order to start appropriate processes that gear the structure of the urban system towards sustainability measures, it is first necessary to reduce urban entropy. New procedures are being developed to plan sustainable cities which, in a cyclical process, are also rooted in social capital. Entropy can be distinguished in directaction, expressed as soil use (how, where, for how long) and entropy-induced action which is carried out by the activities producing air, electromagnetic noise, water pollution. This paper, also starting from the studies developed by E. Tiezzi and the paper by F. Muller (presented at "Sustainable city 2010" in La Coruňa), seeks to identify the characteristics of anthropogenic entropy in order to propose the adoption of a new "urban ethic" which has to become one of the determinants of eco-town planning.

Our concept of urban sustainability is changing along with our evolving modern society. It is related to a number of factors that have an impact on our current understanding of the concept of an urban system. Referring to a systemic approach to understanding the urban system, we can consider urban sustainability as the opposite of urban entropy, which represents both the "dark side of the urban system" and the negative component of each urban subsystem. Within these subsystems, we can identify some driving functions that play an important role in urban sustainability. Nevertheless, when these functions exceed the threshold of urban load, urban entropy increases exponentially. Starting with the very recent changes in urban entropy (as well as urban sustainability) and by assuming that the negative components of the urban system are connected to urban risks, two types of urban entropies can be defined: endogenous and exogenous. The first relates to internal conditions of urban subsystems which unplanned urban management can generate. The second one relates to external causes: natural and anthropic. Within this framework, tourism can be considered as one of the urban functions affecting the organizational process of an urban system. Tourism depends on internal factors and grows by generating exogenous flows. In many cases, tourism plays a fundamental role in an urban economy and it acts as a strategic factor for urban competitiveness. When tourism exceeds urban capacity, it causes urban malfunctions. In this sense, tourism is one of the most sensitive urban functions regarding the process of entropy. Using the systemic approach as a theoretical reference, this paper states that tourism can act as a driving function able to shift the urban system towards sustainable condition if it is integrated into the process of town planning.

It is quite difficult to define what the Smart City is: some studies try to understand urban smartness by considering a set of variables inside the urban system. Most likely, a different method can be found, starting from the assumption that the city could be considered as a complex system. In a way, we can say that the Smart City is a physical space in which technology is widespread, available and inclusive and supports a new growth of social capital, the renewal of the material urban dimension and allows the development of new functional systems throughout the "virtualization" of some urban activities. The process towards the knowledge of "urban smartness" is conditioned to a first step, which is a common phase in the two new dimensions of modern urban planning: sustainable planning and smart planning. Both of these two dimensions try to manage the evolution of the urban system and drive it towards a future state that should be compatible with the available resources as well as sustainable considering the future needs of human beings as well as the planet. In order to initiate the management of territorial transformation, there is one first obligatory step in common with all new urban planning: the reduction of urban entropy. Urban entropy represents the main obstacle to starting new sustainable processes of urban planning and corresponds to all the kinds of urban dyscrasia that can occur within the urban subsystems. In order to reduce urban entropy, we first need to develop a way to identify and to measure it inside the different city subsystems. This paper proposes a useful method which can be used to measure it and to envisage urban actions aimed at reducing negativity of the city by using new technologies.