Energy Consumption is a key constraint in modern computing era. The consumption of energy should be ascertainable not only to Gate Level or Register Transfer (RT) Level but also to the System Level. There is a trade-off between energy consumption and run-time. Researchers are working on low power consumption techniques without degrading performance of the system. The computing science developers focus on both compiler and non-compiler methods for energy minimization. This paper focuses on various techniques, methods and tools for minimization of energy without increasing runtime. The energy consumption and run time computed for various compiler techniques on XScale Architecture using XEEMU tool. The best compiler method picked out and code is tuned dynamically by varying voltage-frequency.