• Weather effects on the energy consumption of manufacturing systems are investigated. • Indoor conditions offset strategy is proposed. • For the implementation, the rust and hygiene of workers are considered. • The effect of the thermal deformation is also experimentally investigated. • Power consumption was reduced by 0.9 kW, 33% in August. Many studies have investigated the energy efficiency of machine tools. However, few have investigated that of entire factories. Air-conditioning systems offer considerable potential for reducing energy consumption. The air-conditioning load is affected by weather, indoor heat generation, and target conditions. This study proposes air-conditioning strategy for energy-efficient manufacturing in consideration of these three factors. The proposed strategy is verified through a simulation using a model established from experimental data. The simulation results show that energy consumption can be reduced significantly. Machining tests were also performed to investigate the thermal displacement induced by air conditioning.