The PIES algorithm presents a new energy saving technique that helps conserve energy that is consumed by the wireless interfaces of ad hoc network nodes. PIES is not a routing algorithm, rather it is an algorithm that works in conjunction with existing routing protocols to help those protocols make decisions regarding energy conservation. PIES functionality conforms to the principle of energy fairness amongst network nodes and does not intervene with the core functionality of the underlying routing protocol. It is a distributed algorithm whose functionality does not depend on any single node or set of nodes within the network. In addition, PIES does not introduce any significant additional traffic or energy costs to the network and its nodes and can be configured to have no additional traffic or energy costs. Simulations show that PIES can generate energy savings of about 50% and extends the lifetime of the network by about 70%.