The Five Point Method of KS and Four Point Method of IES are generally used to measure and compute the average illuminance in residential areas. Such methods of measurement should be used exactly according to the characteristics of the space and activities. Therefore, this study evaluated computation methods of the average illuminance in terms of comparing the measured values with simulated ones. The Five Point Method of KS is very closed to evaluate task illuminancefor appreciating activities at the center while the Four Point Method of IES is very closed to a concept of the average illuminance over the space excluding the possible maximum and minimum illuminance values.