Construction contributes significantly to gas emissions, such as Greenhouse Gases (GHGs) and Criteria Air Pollutants (CAPs). To mitigate negative environmental effects, diverse efforts have been undertaken in construction; however, currently there is no effective tool available for small-scale (e.g., project-based), reliable emission estimation in construction. A new approach to simulating emissions, Discrete-Event Simulation (DES), offers accurate representations of construction operations over time (e.g., equipment utilization rates and duration of use). This approach allows the comparison of emissions from different operational scenarios and can therefore be used in diverse decision-making processes. In this paper, we present a DES-based simulation template created using Simphony, a special purpose simulation environment developed at the University of Alberta. This template permits inexperienced simulators to build simulation models that can estimate emissions of a construction project. A case study of typical aggregate operations in road construction is presented to showcase the model development process. Through its scenario comparisons, daily emissions forecast, and other output analysis, this case study also demonstrates how this simulation-based method can provide valuable information for practitioners to make better decisions on sustainable construction processes. [ABSTRACT FROM AUTHOR]