Electrostatic charge coating systems significantly enhance transfer efficiency (TE) within a shorter processing time. However, as the most significant energy consumption in industrial production, the paint shop plant requires focused attention to improve energy efficiency while ensuring high paint film quality, such as surface durability, corrosion resistance, and mechanical protection. The Nitrotherm electrostatic spray-painting method, with its exceptional transfer efficiency (TE) reaching up to 90% in ideal conditions, offers a shorter process time and eliminates unfavorable phenomena like overspray, subpar film quality, excessive material usage, and significant pollution levels. This method is foundational in the automotive and aerospace coating processes. In the current study, a 3D Eulerian-Lagrangian assessment using the Nitrotherm electrostatic spray method is employed to optimize transfer efficiency and to enhance the painting performance. The implemented algorithm within the OpenFOAM framework incorporates high Reynolds airflow, computed through a Large Eddy Simulation (LES) turbulence approach. It also models spray dynamics, electric field, and droplet tracking for spray coating simulations. The findings suggest that using heated nitrogen-enriched instead of air reduces paint consumption and VOC emissions, while also improving transfer efficiency (TE). The Nitrotherm electrostatic technique also decreases application time by leveraging the low temperature of pure nitrogen for quicker curing, evaporation, and drying, resulting in a higher-quality paint film. This approach contributes to the production of a higher-quality cosmetic paint film on the target, and minimizes overspray, leading to a notably thicker film on the target compared to compressed air.