This study presents a practical design and implementation of a Thermal Management (TM) concept for Battery-Electric Vehicles (BEVs) including a novel Human-Machine Interface (HMI). The developed system uses a combination of convective air conditioning and radiation heating to cool down and heat up the passengers efficiently. The proposed contribution can be subdivided into four parts: 1) description of the Heating, Ventilation and Air Conditioning (HVAC) system; 2) development of a novel HMI; 3) derivation of an appropriate operating strategy concept; 4) validation of the entire TM system based on a user study using a demonstrator vehicle. The results show that the developed TM concept can substantially support the user to operate the HVAC system more efficiently. A user study was conducted to evaluate passenger comfort and usability. The study revealed that users tend to operate a conventional input panel of an HVAC system inefficiently in some cases. They could achieve better task performance with the new HMI proposed in this study. However, the acceptance of the new concept was rated lower for the new system, as users were already accustomed to the conventional input panel design.