Our research focuses on emissions of CO2 along supply chains, from freight energy use and inventories storage. A supply chain model using a discrete event simulation was developed specifically for Carrier, a United Technologies Company. It is able to model a two tiers supply chain. Four tunable variables are provided in the simulation: manufacturing capability, locations, mode of transportation and types of products. Their purpose is to compare levels of CO2 emitted during simulations for differing configurations of different scenarios. The principal objectives of the study are twofold: providing a realistic tool for simulating green supply chains, and a decision help tool.