The model defines energy conversion that occurs during the normal mode and warm-up mode. The model Buildings.Fluid.CHPs.BaseClasses.EnergyConversionWarmUp is used only for the warm-up mode dependent on the engine temperature (case of Stirling engines). The model Buildings.Fluid.CHPs.BaseClasses.EnergyConversionNormal is used for all other cases, i.e. the normal mode, and the warm-up mode based on a time delay (case of internal combustion engines).