This study proposes an optimal temperature feedback control aimed at minimizing the electricity consumption of condenser water loops, saving a significant amount of the total energy compared to the existing control. The developed control can be applied across multiple plants irrespective of their diverse configurations, such as sizes and performances, because the functions used in the energy-efficient control are grounded on the fundamental physics that take place in general condenser water loops. Specifically, we analytically derived the physical equations for the optimal flow rate and temperature of condenser water, identifying key influencing factors thereof. The key factors were then verified using a high-fidelity system simulator using Dymola. Lastly, optimal functions used in the proposed control were suggested using regression analysis, which is consistent with the derived equations. The developed control including optimal functions is expected to be implemented in twelve semiconductor plants in 2025.