  The recent study of SN 2013fs flash spectrum suggests enormous for SN IIP
explosion energy, far beyond possibilities of the neutrino mechanism. The issue
of the explosion energy of SN 2013fs is revisited making use of effects of the
early supernova interaction with the dense circumstellar shell. The velocity of
the cold dense shell between reverse and forward shocks is inferred from the
analysis of the broad \heii\,4686\,\AA\ on day 2.4. This velocity alongside
with other observables provide us with an alternative energy estimate of
$\sim1.8\times10^{51}$\,erg for the preferred mass of $\sim10$\msun. The
inferred value is within the range of the neutrino driven explosion.
