An analysis is presented for the fraction of the energy transported as heat to the workpiece during grinding. The abrasive grains and grinding fluid in the wheel pores are considered as a thermal composite which moves relative to the grinding zone at the wheel speed. The energy partition fraction to the workpiece is modeled by setting the temperature of the workpiece surface equal to that of the composite surface at every point along the grinding zone, which allows variation of the energy partition along the grinding zone. Analytical results indicate that the energy partition fraction to the workpiece is approximately constant along the grinding zone for regular down grinding, but varies greatly along the grinding zone for regular up grinding and both up and down creep-feed grinding. The resulting temperature distributions have important implications for selecting up versus down grinding especially for creep-feed operations.