  We quantify the energy radiated through all the collisionally excited lines
in a photoionized nebula which is permeated by temperature fluctuations. We
assume that these correspond to hot spots which are the results of an unknown
heating process distinct from the photoelectric heating. We consider all the
effects of using a higher mean temperature (as compared to the equilibrium
temperature) due to the fluctuations not only on each emission line but also on
the ionization state of the gas. If this yet unknown process was to radiate a
fixed amount of energy, we find that the fluctuations should correlate with
metallicity Z when it exceeds 0.7 solar. The excess energy radiated in the
lines as a result of the fluctuations is found to scale proportionally to their
amplitude t^2. When referred to the total energy absorbed through
photoionization, the excess energy is comparable in magnitude to t^2.
