A comprehensive model for quantifying the environmental and financial performance of cities

Current models to quantify environmental performance in the built environment are flawed as they typically focus either on one scale of the built environment (e.g. buildings), on a limited range of environmental flows (e.g. energy), or a particular life cycle stage (typically building use). There is a need to develop a more comprehensive model to assess and improve the environmental performance of cities. This paper proposes a multi-scale, bottom-up, dynamic life cycle assessment model for the built environment. The model combines nested systems theory with life cycle assessment and dynamic modelling. It covers all scales of the built environment, from materials to cities. In particular, it considers material, energy, greenhouse gas emissions, water and financial flows required to produce construction materials and replace them (embodied flows); operate buildings and infrastructure assets (operational flows); and for the mobility of building users (transport flows). Furthermore, the model evaluates the value created by a particular real estate development. The paper describes how the model operates and the methods used to quantify each flow. By covering spatial and temporal boundaries across multiple environmental and financial flows, this model will significantly improve environmental assessment and decision-making for actors of the built environment.