Power control is one of the most important issues to be considered in ad hoc networks. Indeed, the choice of the transmission power will have an impact on the received signal strength, on the number of hops required to reach destination nodes, the overall connectivity of the network and their battery life. In this paper, we address the problem of power control so as to miminise the total network energy consumption and provide an optimum routing strategy. We consider CDMA as the communication channel to achieve multiple communications at a given time slot while guarantying a collision free medium access control. We propose a new iterative method which adaptively performs routing, power control and data rate optimisation. Ourapproach minimises the overall network energy consumption under signal to interference ratio constraints. We show that the total energy consumption is reduced when the algorithm is initialised with a routing table resulting from the mimumum spanning tree approach. However, we show that this optimum solution can be approximated when the algorithm is initialised with a very basic routing algorithm.