Many organizations are working towards reducing the carbon footprint of their data centers; i.e. reducing their power consumption. Server virtualization is used to decrease power consumption by consolidating multiple servers onto a few physical machines. Virtualization provides increased flexibility by providing a means to dynamically move virtual machines from one physical machine to another. Using resource utilization as a proxy for power, the authors build models of power consumption for individual server types and use this information along with business value and SLA information, to efficiently allocate virtual machines to physical machines.