Have you ever wondered, when choosing heating in winter, whether a "kotatsu" or an "air conditioner" is better for saving on electricity bills? Each has its own advantages and disadvantages, and electricity costs can vary significantly depending on how you use them. In this article, we compare the electricity costs of kotatsu and air conditioners and explain practical saving tips for each in detail.
How different are the electricity costs of a kotatsu and an air conditioner?
First, let’s compare the electricity costs of both with concrete figures. The actual amount varies depending on room size and the equipment, but the following numbers are a useful guide.
Electricity cost of a kotatsu
The maximum power consumption of a kotatsu large enough for four or more people is 500 to 600W, but in actual use it is around 100W on "low" and around 200 to 300W even on "high."
- Used 8 hours a day (100 to 300W): about 700 to 1,000 yen per month
- For a person living alone (kotatsu under 500W): around 600 yen per month may also be possible
Electricity cost of an air conditioner (heating)
The following is a guideline for a 14-tatami air conditioner (power consumption about 970W) used 8 hours a day.
- Family of four (14-tatami unit): about 6,000 yen per month
- Person living alone (8-tatami unit, 500W): about 3,200 yen per month
Using them differently based on purpose is the smart approach
A kotatsu only warms the area around your feet, but it heats up quickly and uses relatively little power. An air conditioner can warm the entire room, but it takes time to do so and consumes more electricity. If you only want to warm part of the space, a kotatsu is suitable. If you want to warm the whole room, an air conditioner is more appropriate. Using them according to purpose is the basis of saving money.
Even in rental properties, introducing energy-saving equipment directly leads to lower utility costs.
What are 3 tips for reducing the electricity cost of a kotatsu?
A kotatsu is a heating appliance that usually costs less to run than an air conditioner, and with the right usage you can save even more.
Place a carpet or rug underneath
Placing a carpet or rug under the kotatsu helps prevent heat from escaping into the floor and improves heating efficiency. It is even more effective to place an insulating sheet between the carpet and the floor.
Use a kotatsu quilt with the right size and thickness
If you choose a kotatsu quilt that is at least 110 cm larger than the table in total, gaps between it and the floor are reduced and warm air inside is less likely to escape. The thicker the quilt, the better the heat retention.
Keep the setting at "medium" or lower
Because the space inside a kotatsu is smaller than an entire room, a setting of "medium" or lower is usually warm enough. Many people tend to set it to "high," but that often makes it too hot and also increases power consumption. Keeping it at "medium" or lower is the basic principle of saving electricity.
What are 5 tips for reducing the electricity cost of an air conditioner?
Saving on the electricity cost of an air conditioner may seem difficult, but the right usage makes efficient savings possible.
Improve window insulation
Windows are places where warm air can easily escape. Using thick curtains, insulating film, or insulation boards helps block cold air from coming in and warm air from getting out. Choosing high-insulation equipment also contributes to long-term savings.
Run it in auto mode
Some people lock the unit on "low" in an attempt to save electricity, but this can have the opposite effect. An air conditioner uses the most power until it reaches the set temperature. In auto mode, power consumption drops after the target temperature is reached.
Circulate the air
Warm air tends to gather near the top of the room. Using a fan or air circulator to move that warm air helps heat the entire room more efficiently.
Clean the filter regularly
If the filter gets dirty, the performance of the air conditioner drops and electricity costs rise. Cleaning it about once every two weeks helps maintain the unit’s efficiency.
Keep the area around the outdoor unit clear
Placing objects around the outdoor unit reduces heating efficiency. In areas with snowfall, it is also important to take measures to protect the outdoor unit from snow.
Frequently Asked Questions (FAQ)
Q. Which has lower electricity costs, a kotatsu or an air conditioner?
For a person living alone, a kotatsu typically costs about 600 to 1,000 yen per month, while an air conditioner costs about 3,200 yen per month. In simple electricity-cost terms, the kotatsu is much cheaper.
Q. Does running an air conditioner on "low" save electricity?
No. The unit uses the most electricity while running at full output until it reaches the set temperature, so keeping it on low for a long time can actually increase electricity costs. Auto mode is the most efficient option.
Q. Is it okay to leave a kotatsu on all night?
Doing so wastes electricity and also creates a risk of low-temperature burns. Turn the kotatsu off before going to bed, and if necessary use another heating method such as an electric blanket.
Q. How often should you clean an air conditioner filter?
About once every two weeks is a useful guideline. In winter and summer in particular, when usage is high and dirt builds up more easily, regular cleaning directly contributes to lower electricity costs.
Q. What is the best way to use a kotatsu and an air conditioner together?
The most efficient approach is to warm the whole room quickly with the air conditioner, then use the kotatsu to keep only your feet warm after the set temperature has been reached. This reduces the need to run the air conditioner for long periods and helps keep electricity costs down.
