This paper describes a procedure for minimizing the power consumption in a boolean network under the zero delay model. Power is minimized by modifying the function of each intermediate node in the network such that the power consumption of the node is decreased without increasing the power consumption of the other nodes in the network. A formal analysis of how changes in the switching activity of an intermediate node affect the switching activity of other nodes in the network is given first. Using this analysis, a procedure for calculating the set of compatible power don't cares for each node in the network is presented. Finally it is shown how these don't cares are used to optimize the network for low power. These techniques have been implemented and results show an average of 10% improvement in total power consumption of the network compared to the results generated by the conventional network optimization techniques.