  We consider the energy savings that can be obtained by employing network
coding instead of plain routing in wireless multiple unicast problems. We
establish lower bounds on the benefit of network coding, defined as the maximum
of the ratio of the minimum energy required by routing and network coding
solutions, where the maximum is over all configurations. It is shown that if
coding and routing solutions are using the same transmission range, the benefit
in $d$-dimensional networks is at least $2d/\lfloor\sqrt{d}\rfloor$. Moreover,
it is shown that if the transmission range can be optimized for routing and
coding individually, the benefit in 2-dimensional networks is at least 3. Our
results imply that codes following a \emph{decode-and-recombine} strategy are
not always optimal regarding energy efficiency.
