Air Conditioner Cost Calculator (Japan) — Cooling and heating cost per day, month and season from room size and set temperature
Estimate what your air conditioner costs to run in Japan, for cooling or heating, from room size in tatami mats, set temperature, hours of use and the age of the unit. See daily, monthly and seasonal costs and how much each degree changes the bill.
Pick your room size and set temperature to see what cooling or heating with the air conditioner costs.
Air Conditioner Cost Calculator: tips and things to know
- Raising the cooling set point by 1°C saves about 13% of the electricity; lowering the heating set point by 1°C saves about 10%.
- An air conditioner more than 10 years old can cost 1.3 to 1.5 times as much to run as a current model.
- Cleaning the filter every two weeks saves roughly 5 to 10 percent.
How to use the Air Conditioner Cost Calculator
Choose cooling or heating
Pick the mode you want to estimate.
Choose the room size
Select the room size in tatami mats (jo) that matches your unit.
Enter the conditions
Set the temperature, hours per day, days per month and the efficiency of your unit.
Read the result
The cost per day, month and season appears with the estimated power draw.
Air conditioners heat as well as cool in Japan
Most Japanese homes have no central heating. The wall-mounted air conditioner (eakon) in each room is both the summer cooler and, in most of the country, the main winter heater. That is why this tool has a heating mode, and why winter bills are often higher than summer ones.
Units are sized by room area in tatami mats (jo): a "6-jo" model suits a room of about 10 m². Choose the size closest to your room; an undersized unit runs harder and costs more.
The 28°C summer and 20°C winter guideline
The Ministry of the Environment recommends a room temperature of 28°C in summer and 20°C in winter as a balance between comfort and energy use. Note that these are room temperatures, not the number on the remote; a unit set to 26°C is what many households actually use, and the tool starts there.
The saving from each degree is large because the unit works against the gap between outside and inside temperatures, and Japanese summers are hot and humid.
On all day or switch off?
Start-up draws the most power, so for absences of 30 minutes to an hour it is cheaper to leave the unit running than to switch it off and on. For several hours away, switching off saves money.
Using the dry (除湿, joshitsu) mode in humid weather and pairing the unit with a fan (circulator) lets you set a higher temperature for the same comfort.
Air Conditioner Cost Calculator FAQ
Is it cheaper to leave the air conditioner on?
For short absences of up to about an hour, yes, because start-up uses the most power. For longer absences, switch it off.
Which costs more, cooling or heating?
Heating, in general. The gap between outdoor and indoor temperature is larger in winter, sometimes over 20°C, so the unit works harder.
Should I replace an old unit?
A unit over 10 years old can use 30 to 50 percent more electricity than a new one. The annual saving is often ¥10,000 to 20,000, so replacement usually pays for itself over time.