An important requirement of interweave cognitive radio networks is spectrum sensing. There are several techniques to detect available spectrum holes, but energy detection is still the most common spectrum sensing scheme. In this work, we provide a performance study of energy detection spectrum sensing in cognitive radio networks operating in the interweave spectrum sharing context. The key performance parameters of energy detectors, i.e., detection and false alarm probabilities, are revisited. Numerical examples with various combinations of system parameters (spectrum sensing overhead, primary signal-to-noise ratio, and probability of the primary user activity) are provided to illustrate the accuracy of our analysis, and highlight the intrinsic tradeoff between primary and secondary users interests in the interweave context.