Simulated white dwarf luminosity function for a pure DA white dwarf population (open triangles) and for a population in which a canonical fraction of 20% of non-DA white dwarfs (open circles) is adopted. Both luminosity functions are compared with the observational white dwarf luminosity function (solid squares) of Harris et al. (2006; left top panel) and Rowell & Hambly (2011; right top panel). In the bottom panels, we show the residuals between the synthetic luminosity functions.