There are various kinds of Internet of Things (IoT) services like home management services. In the IoT services, a large volume of data is gathered from various types of smart devices and is manipulated in scalable, high performance, and fault-tolerant computing systems like cloud computing systems. Reliable and available IoT services can be provided by replicating each application process on multiple virtual machines in a server cluster system. On the other hand, a server cluster system with process replicas consumes a larger amount of electric energy than non-replication approaches. Hence, not only fault-tolerant but also energy-efficient server cluster systems by using virtual machine technologies are required to realize IoT services. In this paper, a redundant energy consumption laxity based (RECLB) algorithm to redundantly and energy-efficiently perform each application process on multiple virtual machines is newly proposed. The RECLB algorithm is evaluated in terms of the total electric energy consumption of a server cluster and the average computation time of each process in both homogeneous and heterogeneous server clusters.