Silicon crystal， as the primary raw material for solar cells， plays a critical role in determining solar cells manufacturing costs. Consequently， reducing power consumption during monocrystalline silicon growth is pivotal for cost reduction and efficiency improvement in the photovoltaic industry. This study develops a global three-dimensional （3D） numerical model for the Czochralski （CZ） silicon growth， considering non-axisymmetric components such as heaters and electrodes in the CZ furnace. This modeling approach allows for more precise simulations of fluid flow and heat transfer in the CZ furnace. Based on the numerical model， the influence law of the emissivity of cold and hot side in heat shield on power consumption distribution and heat transfer paths of radiation， convection， and conduction in the CZ furnace was analyzed. The results indicate that reducing the emissivity on both cold and hot side significantly decreases power consumption， with a more pronounced effect observed on the cold side. In terms of radiative heat transfer， reducing the heat shield emissivity decreases the heat absorbed by the graphite crucible and the hot side of heat shield， as well as the heat releasing from the silicon melt and the cold side of heat shield. Furthermore， a slight increase in heat absorption by the top insulation is observed when the emissivity of the hot side is reduced. In terms of convective heat transfer， the reduction in cold side emissivity increases the heat absorbed by the water-cooling jacket， and the heat releasing from the cold side of heat shield. In contrast， the impact of hot side emissivity on convective heat transfer is comparatively minor. In terms of conductive heat transfer， lowering the emissivity on both sides of heat shield decreases heat conduction from the hot to cold side of heat shield， as well as from the graphite crucible to the quartz crucible， and from the quartz crucible to the silicon melt. These results provide critical theoretical insights for the precise and deep optimization of energy-saving strategies in industrial CZ furnaces.