Recent years have seen an increase in the interest and application of the low-loss region (<~50 eV) of electron energy-loss spectroscopy (EELS). The spectral detail in this region is associated with excitations of the valence electrons and includes interband transitions and collective excitations. As a consequence, the valence EELS displays a rich and complex array of spectral features. The valence EELS is directly connected to optical response functions and there are a number of sophisticated density functional theory (DFT) based approaches available to calculate these. However, the large energy range required for EELS data puts unique demands on the computational processing required and careful selection of the appropriate level of calculation is necessary. In the simplest approximation, the independent particle approximation (IPA), the electron and hole generated are assumed to not influence the other electron states and do not interact with one another. That is, quasiparticle and excitonic effects are ignored. This approach works for some systems but is a poor approximation for many others. Sometimes the inclusion of local field effects (LFE) are important and sometimes computationally expensive approaches can be avoided by using alternative exchange-correlation potentials instead. This presentation will demonstrate the applicability of various levels of computation to modelling EELS spectra for a range of different materials.