Technology scaling has resulted in an exponential increase in the leakage power as well as the variations in leakage power of fabricated chips. Functional units (FUs), like Integer ALUs are regions of high power density and significantly contribute to the variation in the whole processor power consumption. Hence, it is important to reduce both the power consumption and the variation in power consumption of the FUs. Among existing FU power reduction techniques, power gating (PG) has been most effective. In this paper, we introduce a leakage sensor inside the FUs and propose a temperature and process variation aware power gating scheme, Leakage Aware Power Gating (LA-PG). Our experimental results demonstrate that LA-PG results in 22% reduction in mean and a 25% reduction in standard deviation of the ALU energy consumption when compared to existing power gating techniques, without significant performance penalty.