  The lattice data for the energy density of $SU(2)$ gauge theory are
calculated with \nop~derivatives of the coupling constants. These derivatives
are obtained from two sources : i) a parametrization of the \nop~beta function
in accord with the measured critical temperature and $\Delta\beta-$values and
ii) a \nop~calculation of the presssure. We then perform a detailed finite size
scaling analysis of the energy density near $T_c$. It is shown that at the
critical temperature the energy density is scaling as a function of $VT^3$ with
the corresponding $3d$ Ising model critical exponents. The value of
$\epsilon(T_c)/T^4_c$ in the continuum limit is estimated to be 0.256(23). In
the high temperature regime the energy density is approaching its weak coupling
limit from below, at $T/T_c \approx 2$ it has reached only about $70\%$ of the
limit.
