Key Management is one of the main components of secure communication and is considered one of the most energy consuming during the process. The emergence of resource constrained elements in the Internet of Things (IoT) crucially requires a key management scheme that is suitable for those devices in terms of resource consumption. In this paper, an adaptive key management scheme is proposed where the server can send a number of values that the client can use to generate the keys. This scheme ensures that the amount of values sent between nodes is based on the energy available at the receiving node for key generation. Our protocol is designed to suit a dynamic environment, with a high number of joins, predicted and unpredicted leaves while maintaining the security level required. A typical case in our approach can save an average of 20-30% of energy consumed in generating keys in comparison to other key management systems.