The increasing electrification of road transport places demanding requirements on the efficiency, safety, and sustainability of thermal management systems in electric vehicles. The growing number of electric vehicles amplifies cumulative energy demand at the system level, making the optimization of onboard energy consumption important to limit loads on existing power generation and distribution system. In particular, the choice of refrigerant plays a critical role in determining system performance, environmental impact, and compliance with evolving regulations. This paper presents the concept and preliminary development of an integrated thermal management system (ITMS) for an electric vehicle based on the natural refrigerant R290 (propane), developed within an industrial partner - TI Automotive. R290 offers significant advantages in terms of low global warming potential (GWP), favorable thermodynamic properties, and high energy efficiency compared to conventional fluorinated refrigerants. However, its application in automotive systems is constrained by safety considerations related to flammability, charge limitations, and system architecture. The presented concept addresses these challenges through a holistic system design approach, integrating cabin heating and cooling, battery thermal management, power electronics cooling, and waste heat recovery. A key focus of this work is development of the correlation between refrigerant charge and thermal management system capacity and performance. Heating and cooling modes of the system were analyzed in order to evaluate trade-off between safety margins and the coefficient of performance (COP) under varying ambient conditions. The paper aims to demonstrate that an optimized R290 TMS architecture can provide a viable, high-efficiency solution for next-generation electric vehicles, offering a pathway to decarbonization without compromising passenger safety or thermal comfort.