A GIS based entropy approach to the spatial aspects of urban renewal

The second law of thermodynamics, entropy, asserts that each energy cycle in the universe reduces the quality of the energy and this reduction is irreversibly discharged into space in the form of waste heat. Since the 19th century this statement has lead to the idea that the entropy of the Earth as a part of the universe is constantly increasing and this chaotic process is leading it to destruction. Cities as parts of the closed system of the Earth, generate open systems with their dynamic structure and play a major role in the entropy increase of the Earth. Therefore, cities were among the first to be spatially affected by the decay caused by entropy increase and gave birth to urban renewal trends as an overarching concept over all sorts of urban interventions. The concept of entropy has been used mainly by physics until 1948. Following the establishment of a relationship between statistics and entropy it has been adopted by several different disciplines. The uses of entropy on an urban scale have been mostly oriented towards Shannon Entropy and a clear connection to thermodynamics has not been developed. The aim of this study is to evaluate the concept of entropy on an urban scale and establish connections from a macroscopic scale to a microscopic scale within thermodynamic systems, and to develop the concepts of urban entropy and urban negentropy at the urban scale where thermal increase and matter chaos influence space. In this regard, the causes of urban entropy under the concept of urban renewal were determined and their levels of influence measured through the Analytic Hierarchy Process evaluated by experts, and building block based spatial analysis was performed in Bağcılar district taken as a demonstration site through Geographical Information Systems. An entropy based spatial decision support matrix has been established as the original method of this study and the urban entropy values of building blocks calculated to map entropy as a visually for the first time. The study stands against the idea of reducing urban renewal to generating high rise urban space and advocates urban interventions where natural resources are conserved and renewable energy sources are encouraged