Construction operations have a tremendous impact upon both the environment and public health due to the generation of significant amounts of airborne emissions, including greenhouse gases and other traditional criteria air pollutants. Quantifying emissions in the pre-planning phase of construction operations is the first step in identifying mitigation opportunities. The authors therefore have quantified construction emissions produced by various types of construction operations through the use of discrete-event simulation (DES). The paper focuses upon the utilization of DES in various case studies and delineates the lessons learned. An overview of each case project is provided, the benefits and limitations of DES are identified, and means to mitigate these limitations are discussed. The lessons learned from the case studies utilized in the paper are helpful; simulation practitioners and researchers can exploit these studies in simulation models that examine the environmental aspects of construction operations.