Abstract. A model for the coupled mass and energy balances of snow on the ground requires representations of absorption of solar radiation by snow, heat conduction in snow, compaction of snow, transfer of heat to snow from the air and retention and refreezing of meltwater in snow. Many such models exist, but it has proven hard to relate their relative performances to the complexity of their process representations. This paper describes the systematic development of an open-source snowpack model with two levels of representation for each of the five processes mentioned above, allowing factorial experimental designs with 32 different model configurations. The model is demonstrated using driving and evaluation data recorded over one winter at an alpine site.