Building upon the foundation of thermal management system metrics developed and published from earlier studies, this paper addresses the incorporation of the vehicle Environmental Control Systems (ECS) into this framework. Case studies are presented that look at the implications of several ECS alternatives on a conceptual military, hybrid electric vehicle platform through exemplar calculations of thermal management system (TMS) metrics. Utilization of these metrics allows for the comparison of design alternatives through a conceptual design case study. Two sets of case studies are evaluated in tandem within this study. In the first, the effect of cabin air-cooled component heat rejection is compared to direct TMS liquid-cooled heat rejection alternatives. The considerations of performance, packaging and reliability concerns are discussed. In the second set of case studies, variations in vapor compression cycle thermodynamic states are considered to provide metric-based guidance on design alternatives.