We evaluated the air-conditioning heat load of spot air-conditioning system in a large space building like a factory by a coupled simulation of convention, radiation, moisture transportation and air-conditioning system control under constant PMV condition. The energy saving performance of this system was evaluated in comparison with the results of occupied zone air-conditioning system. The following results were obtained: 1) Indoor surface temperature was higher and thermal transmission load was lower in spot air-conditioning. 2) PMV values at eight evaluation points were almost the same in spot air-conditioning. 3) Sensible heat load decreased one third by making the set value of PMV lower from 2.0 to 0.5 in occupied zone air-conditioning, and one fourth in spot airconditioning. 4) Sensible heat load decreased two third by making the air temperature at supply opening lower from 20oC to 12oC in occupied zone air-conditioning, and three fifth in spot airconditioning.