  We investigate the behavior of energy fluctuations in several models of
granular gases maintained in a non-equilibrium steady state. In the case of a
gas heated from a boundary, the inhomogeneities of the system play a
predominant role. Interpreting the total kinetic energy as a sum of independent
but not identically distributed random variables, it is possible to compute the
probability density function (pdf) of the total energy. Neglecting correlations
and using the analytical expression for the inhomogeneous temperature profile
obtained from the granular hydrodynamic equations, we recover results which
have been previously observed numerically and which had been attributed to the
presence of correlations. In order to separate the effects of spatial
inhomogeneities from those ascribable to velocity correlations, we have also
considered two models of homogeneously thermostated gases: in this framework it
is possible to reveal the presence of non-trivial effects due to velocity
correlations between particles. Such correlations stem from the inelasticity of
collisions. Moreover, the observation that the pdf of the total energy tends to
a Gaussian in the large system limit, suggests that they are also due to the
finite size of the system.
