  We present first results of an implementation of chemical evolution in a
cosmological hydrodynamical code, focusing the analysis on the effects of
cooling baryons according to their metallicity. We found that simulations with
primordial cooling can underestimate the star formation rate from $z < 3$ and
by up to $\approx 20 %$. We constructed simulated spectra by combining the star
formation and chemical history of galactic systems with spectra synthesis
models and assess the impact of chemical evolution on the energy distribution.
