In this paper, we consider a dynamic sensing level selection and energy limitation problem for wireless sensor networks. Accurate, reliable and timely sensing information needs more frequent sensing. In other words, energy is necessary for sensing operation. This implies a trade-off between sensing rate and energy consumption. In this paper, we propose the practical energy-sensitive approach exploiting such a trade-off, where sensing rate can be changed dynamically depending on coverage statistics and event detection utility. We formulate energy efficient problem under Markovian assumptions, where the objective is to provide a certain degree of coverage capacity and probability so as to maximizethe network lifetime. We provide the mathematical modeling of the dynamic sensing level selection, and an algorithm for exploiting the trade-off between energy and sensing level. Finally, we derive the boundary issue of our suggestion.