With the rapid growth of the cloud industry in recent years, energy consumption of warehouse-scale datacenters has become a major concern. Energy-aware Virtual Machine consolidation has proven to be one of the most effective solutions for tackling this problem. Among the sub-problems of VM consolidation, VM placement is the trickiest and can be treated as a bin packing problem which is NP-hard, hence, it is logical to apply a heuristic approach. The main challenge of VM consolidation is to achieve a balance between energy consumption and quality of service (QoS). In this research, we evaluate this problem and design a combined strategy using best fit decreasing bin packing method and multi-pass optimization in VM placement for an efficient VM consolidation. We have used CloudSim toolkit to simulate our experiments. To evaluate the performance of the proposed algorithms we used real-world workload traces from thousand VMs. Results demonstrate that our proposed methods outperform other existing methods.