Apartments account for 64.6% of all housing units in the Republic of Korea, and most of them receive electricity under a contract, which includes a progressive rate plan. Recently, due to the electrification of energy used in homes and the growing adoption of electric vehicles, electricity consumption in apartment complexes has been gradually increasing. Given the characteristics of the progressive rate system, an increase in electricity usage results in a significant higher rise in electricity bills. Thus, an effective alternative is required to reduce electricity bills for each household. In this paper, the savings in electricity bills achieved by reducing household electricity usage are analyzed from both apartment complex and individual household perspectives, using metering data from 13,332 households. When households are sorted by the amount of savings in descending order, the resulting values are found to follow a negative exponential curve. This indicates that the benefits from reducing electricity usage in households with higher saving are significantly larger compared to other ones. We analyzed bill savings when electricity usage reductions were selectively applied to the top 10%, 20%, and 30% of households with the largest savings. From the results, it is found that the largest savings in electricity bills for households are achieved when usage reductions are applied to the top 10% of households. It is expected that this amount of savings would encourage these households to reduce their electricity consumption. Additionally, it is found that the savings for apartment complexes and the total savings for selected households are not the same, resulting in changes in the bills for households that do not reduce their usage. From the results, it was observed that when the usage reduction of selected households is small or the proportion of households reducing usage is low, the common area charges for non-reducing households tend to increase, leading to higher electricity bills. On the contrary, when the usage reduction of selected households is large or the proportion of households reducing usage is high, the common area charges for non-reducing households tend to decrease, resulting in lower electricity bills.

To charge the electric energy for electric vehicles (EVs), various charging rate plans have been developed based on AC slow charging and DC fast charging. Flat rate plans are available for both AC and DC charging, where the EV charging fee typically depends on the amount of electric energy used for charging. For AC charging, a dynamic rate plan of time-of-use (TOU) is provided in addition to the flat rate plan. For DC charging, there are also subscription or membership rate plans that are driven by promotions for purposes such as car sales or encouraging the use of specific charging stations. In this paper, by formulating charging equations in terms of the charging fees, we first summarize and compare the various charging rate plans currently being commercialized. Furthermore, assuming a combined usage scenario of both AC and DC charging, combined charging plans of the flat and TOU rates for AC charging, and the flat and subscription rates for DC charging are analyzed. Through simulations based on charging fee formulations for the combined charging scenario, the analyses are conducted and appropriate charging plans for specific driving distances and DC charging portions depending on the EV drivers are suggested. The formulations in this paper can be extended to accommodate various charging rates and base fees, providing specific guidelines selecting for appropriate charging types.