  Network Function Virtualization (NFV) has recently received significant
attention as an innovative way of deploying network services. By decoupling
network functions from the physical equipment on which they run, NFV has been
proposed as passage towards service agility, better time-to-market, and reduced
Capital Expenses (CAPEX) and Operating Expenses (OPEX). One of the main selling
points of NFV is its promise for better energy efficiency resulting from
consolidation of resources as well as their more dynamic utilization. However,
there are currently no studies or implementations which attach values to energy
savings that can be expected, which could make it hard for Telecommunication
Service Providers (TSPs) to make investment decisions. In this paper, we
utilize Bell Labs' GWATT tool to estimate the energy savings that could result
from the three main NFV use cases Virtualized Evolved Packet Core (VEPC),
Virtualized Customer Premises Equipment (VCPE) and Virtualized Radio Access
Network (VRAN). We determine that the part of the mobile network with the
highest energy utilization prospects is the Evolved Packet Core (EPC) where
virtualization of functions leads to a 22% reduction in energy consumption and
a 32% enhancement in energy efficiency.
