An input-output simulation model for assessing production and environmental waste in construction

Traditionally, the focus of lean construction has been on production waste (a component of production that does not add value to the system) while environmental waste (unnecessary use of resources or a substance released into the air, water, or land) has been the focus of sustainable construction. Production and environmental wastes are dependent. However, they are separately assessed in construction. Developing methodologies to simultaneously assess production and environmental performance is still a significant challenge in construction. This paper explores the impact of lean production on the environmental performance of construction projects to propose a framework for simultaneous management of production and environmental waste. A hypothetical project is illustrated by simulation, which integrates a Discrete-Event Simulation (DES) model of construction operations and an Input/Output (I/O) framework for environmental loads. Preliminary results show that the DES-I/O framework is capable to not only reduce project time and cost with better resource utilization, but also to demonstrate energy savings and a decrease in greenhouse gas emissions.