This paper proposes a design-time (offline) analysis technique to determine application task mapping and scheduling on a multiprocessor system and the voltage and frequency levels of all cores (offline DVFS) that minimize application computation and communication energy, simultaneously minimizing processor aging. The proposed technique incorporates (1) the effect of the voltage and frequency on the temperature of a core; (2) the effect of neighboring cores' voltage and frequency on the temperature (spatial effect); (3) pipelined execution and cyclic dependencies among tasks; and (4) the communication energy component which often constitutes a significant fraction of the total energy for multimedia applications. The temperature model proposed here can be easily integrated in the design space exploration for multiprocessor systems. Experiments conducted with MPEG-4 decoder on a real system demonstrate that the temperature using the proposed model is within 5% of the actual temperature clearly demonstrating its accuracy. Further, the overall optimization technique achieves 40% savings in energy consumption with 6% increase in system lifetime.