The low-entropy city: A thermodynamic approach to reconnect urban systems with nature

Abstract

Starting from the literature regarding the thermodynamics of open systems, the circular economy of Nature and complex socio-ecological systems, we propose a new boundary concept of a low-entropy city as the grounds on which to build actions and political strategies aimed at increasing urban sustainability.A low-entropy city is defined as a responsive and conscious autopoietic human sociocultural niche that evolves and grows, enhancing its socio-ecological and structural complexity (reducing internal entropy) by adding and optimizing functional elements and synapses among those elements, while wastes (exported entropy to the biosphere) are minimized.In particular, the low-entropy city concept is explored considering the role of Urban Green Infrastructure (UGI) in reducing city entropy. Following an analysis of the literature and applied research on UGI, the second law of thermodynamics and urban planning, a seminal nature-based planning strategy for low-entropy cities is presented. With appropriate adaptations, the strategy is applicable to all cities, despite the fact that urban systems can have different levels of UGI efficiency, different approaches to sustainability, and different demands for services as well as pressing environmental, social and economic issues. Some new entropy indicators are then presented, based on low-entropy city principles and two exemplificative urban evaluations based on these indicators are examined: urban storm water management and social degradation.Finally, the low-entropy city concept and its implications in the urban sustainability debate are discussed, considering the possible difficulties that might be encountered when translating it into practice.