Impact-Based Allocation of Common-Area Electricity Charges in Apartment Complexes

Under the single contract (SC) used in apartment complexes in the Republic of Korea, the total electricity consumption of an apartment complex is measured by a main electricity meter, and the residential high-voltage (HV) progressive tariff is applied to calculate the total electricity bill. The difference between the total electricity bill charged to the apartment complex and the sum of the electricity bills calculated for individual households constitutes the common-area electricity bill, which is generally allocated equally among households. However, because the residential progressive tariff is applied to the total electricity consumption, the common-area electricity bill depends not only on the electricity consumption of common-area facilities but also on the distribution of electricity consumption among individual households. Therefore, an allocation method that considers the impact of individual households on the common-area electricity bill is required. In this study, the impact value of each household on the common-area electricity bill is quantified by the change in the bill resulting from the inclusion of that household. Based on these impact values, proportional (PROP) and additive (ADD) allocation schemes are proposed, along with their nonnegative (NN) variants to prevent negative charges. A bounding method is also proposed to impose upper and lower bounds on the allocated charges. The proposed schemes were investigated using actual metering data collected from 13,335 households over 24 months, and their characteristics were analyzed and compared. The results show that PROP exhibits the largest changes in the allocated common-area electricity charges, whereas PROP-NN results in relatively smaller changes from the current uniform scheme. ADD and ADD-NN provide intermediate alternatives, with ADD generally showing larger changes than ADD-NN. Thus, PROP is suitable when the impact value is to be reflected strongly, whereas PROP-NN is preferable when relatively small changes in charges are desired. The bounding method is recommended for PROP and can be optionally applied to the other schemes.