This paper presents a System level Model Driven Architecture (MDA) approach for power estimation of real time operating system (RTOS) communication and synchronization services at early design phases. The approach integrates the Architecture Analysis and Design Language (AADL) in the design flow. We describe how to extend the language for modeling RTOS communication and synchronization services, and we explain how power consumption analysis can be performed on software components in the AADL platform independent model (PIM), once deployed into components in the AADL target hardware platform model. Operating system services are considered as components in the MDA approach in order to take them into account in the estimation methodology. This paper focuses on consumption analysis of RTOS communication and synchronization services.