Due to the continuous change in the topology of ad hoc networks and the lack of a central directory for publishing web services, makes the process of finding web services a very difficult challenge, several approaches have been proposed, all these solutions are based on either a keyword or ID representing the service to be searched, or using a specific scenario of discovery, all this with trying to respect the constraints of ad-hoc networks such as energy, bandwidth ... etc. In this work we proposed a model for measuring the cost of the overall energy consumption in ad hoc networks depending on the mechanisms proposed by the approaches and protocols for discovering web services.