Will Running the Air Conditioner All Day Lead to a Huge Power Bill?... The Key to Saving Is '450kWh'

Electricity Bill Surges as Soon as You Enter Step 3

Cooling Efficiency Determines Your Power Costs

How much will the electricity bill be if you run the air conditioner all day?

As record-breaking heat waves continue day after day, the use of air conditioners is soaring. Due to the temporary easing of the progressive rate band (300·450 kWh) in July and August, the burden of running an air conditioner is relatively reduced as long as usage does not exceed 450 kWh. However, if this threshold is exceeded,the electricity bill rises steeply, making it essential to manage your consumption.

An apartment mailbox in Seoul has a maintenance fee notice delivered. Photo by Jinhyung Kang

The most important benchmark for summer electricity bills in households is 450 kWh per month. The residential electricity rates set by Korea Electric Power Corporation (KEPCO) follow a three-stage progressive system. In July and August, the thresholds are temporarily relaxed due to increased cooling demand. During this period, Step 1 applies to usage up to 300 kWh, Step 2 for 301–450 kWh, and Step 3 for usage exceeding 450 kWh.

The issue arises as soon as you go over 450 kWh. Entering Step 3 of the progressive rate means both the basic charge and the power consumption rate increase sharply, so the total bill rises dramatically. In fact, an electricity bill that is about 85,740 won at 450 kWh usage jumps to 108,460 won—a 26% increase—when consumption increases by just 10% to 495 kWh.

Average households face the '100,000 won threshold'

Even for an average four-person household, the situation is not easy. According to KEPCO, a household electricity bill that was around 52,840 won in spring rises to 95,060 won in summer with average cooling usage alone.

The increase in electricity consumption is even greater during particularly hot years such as recently. In fact, last year, which saw higher summer temperatures, electricity consumption during summer increased by 20.0% compared to spring and fall. This is a significant gap compared to the relatively mild year of 2020, when the increase was only 3.9%.

If consumption exceeds 1,000 kWh, the 'super user tariff' applies

If usage goes above 1,000 kWh, the burden rises much more steeply. Running an air conditioner with power consumption of 1 kWh for 24 hours a day throughout the month adds about 720 kWh, bringing the total usage to 1,000 kWh. In this scenario, the electricity bill soars to around 290,320 won—more than five times the usual 50,000-won level.

At this point, the 'super user tariff' is applied. This system imposes a high electricity usage charge of 736.2 won per kWh on households consuming more than 1,000 kWh per month as a measure to discourage excessive electricity use.

As of 2022, there were 34,834 households subjected to this tariff. While the number itself is not large, the longer the heat wave lasts, the more households are likely to cross into this bracket.

'Efficiency' Matters More than Hours of Use

Experts advise that instead of simply reducing usage time to save on electricity bills, focusing on increasing cooling efficiency is more important. The key lies in the way the air conditioner operates.

Air conditioner reference photo. Pixabay

For non-inverter (fixed-speed) air conditioners, the compressor repeatedly switches on and off, leading to higher power consumption. In this case, running the unit for a certain time and then turning it off is more efficient. In contrast, inverter air conditioners automatically adjust output according to the room temperature, so it is more energy-efficient to maintain a set temperature rather than repeatedly turning the unit on and off.

Using a fan or air circulator alongside the air conditioner can circulate cool air more quickly, lowering the perceived temperature. Blocking direct sunlight with curtains or blinds can also help keep the indoor temperature from rising.

To reduce this burden, KEPCO is operating a pilot for about 2.3 million households with a 'real-time notification service for changes in progressive electricity bands' for residential use. This service sends an alert when household electricity usage reaches 80% of the Step 3 threshold, helping users manage their consumption in advance. The scope of this service will be gradually expanded in the future.

This content was produced with the assistance of AI translation services.