Localizing, identifying and authenticating the individual occupants is of paramount importance for the future intelligent buildings. Although the performance of outdoor positioning systems is sufficiently good, the indoor ones have still to converge to a universal interoperable technology. This paper proposes a hybrid, unified localization architecture for indoor and outdoor tracking of the building occupants. By taking advantage of the smartphones and their recent near field communication (NFC) capabilities; a low cost, accurate and scalable localization solution is proposed. This system is a module of an existing, modern building management system (BMS) to which it offers location-aware, energy and comfort management capabilities. The solution is currently deployed as a medium scale trial; therefore, the self-energy use, reliability, ease of use and the privacy requirements are of paramount importance. The system analysis in this paper additionally includes accuracy and battery impact assessment in real-world use cases and location-aware building management operations.