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Keeping Warm

Author: Paul Granberg, Issue: October 2004, Topic: Household

As with everything in Japan, the Japanese have developed their own unique way of surviving the winter months as well. Read on to learn the best way for you to avoid freezing this winter.

Ever wondered why during the summer months you could never keep you apartment cool, no matter how high you turned the air conditioner up. Most Japanese apartments have no insulation. Only in the last 10 - 20 years have Japanese housing companies caught onto the fact that people like to stay cool in summer and warm in winter. Since many foreign residents live in buildings that are older than most (putting it politely), we often have to make do without this luxury.

Probably the best strategy during winter is to designate one room of your apartment the 'warm' room. This will usually your living room. The next step is to keep it at a toasty temperature.

Kerosene Heaters

This is the most popular kind of space heating in Japan due to the costs involved. An 18 litre container of kerosene can be purchased from you local home store for about 600-800 yen and this will provide you with over 50 hours of continuous heating at full power (the equivalent of 3000 watts of electrical heating). There are several types of kerosene heaters available for purchase.

Tips for Using Kerosene Heaters

  • Kerosene is touyu in Japanese.
  • Store kerosene on your apartment deck or outside. Refill your tank outside your apartment to avoid getting that horrible smell inside.
  • Don't ever refill a hot or operating heater. Turn it off and wait for it to cool down first.
  • Use 'fresh' kerosene. Kerosene is an excellent growth medium for bacteria that will harm your heater. Damaged heaters don't burn fuel well and this leads to Carbon Monoxide being emitted = BAD
  • Purchase an electric pump for refilling your heater from the kerosene container. They usually cost around 300 yen for the basic models to 1,500 yen to the ones with an automatic cut out.
  • Ensure that the flame colour is BLUE in your heater. YELLOW flame and soot is a sign that your heater is giving off deadly Carbon Monoxide gas.
  • Never go to sleep with the heater running.
  • Never use anything but heating kerosene as fuel.
  • Make sure that you have a couple of windows that are partly open in your house to keep the air circulating. Often on sliding doors there is a small sliding window built into the frame for this purpose.


  • Make sure that the dust filter on the back of your fan heater is free of lint
  • Occasionally use a fuel system cleaner. You can buy small bottles of this at your local hardware store for about 300 yen. Just empty the bottle into a full 18L kerosene tank and use the kerosene as normal.

At the End of winter

  • Completely drain your heater and tanks of all kerosene prior to storage. You may need to sit it outside on your deck running to do this.
  • Place it inside a rubbish sack to prevent it becoming home to all kinds of creepy crawlies. Put some fresh batteries in there in case you need to use it in a hurry.

Pot Belly Heaters

In a word. Don't. They smell, they're messy, difficult to refill without spilling kerosene everywhere . . . and have I mentioned that they smell. About the only thing that they have going for them is that they're cheap. You can purchase one at your local home store for around 6-8,000 yen. My advice would be to spend a little more and get a kerosene fan heater.

Radiant Heaters

They're a little better than the pot-belly heater in terms of their design, but that's about it. They have a lift out kerosene cell inside which means that you don't have to take the whole heater outside to refill them. These things still smell quite a bit when they're heating up and cooling down. Once again, save your money and purchase a fan heater.

Fan Heaters

These things are the best kind of kerosene heaters. They have electronic ignition, timers, thermostats, lift out kerosene tank, carbon monoxide detectors and a fan to blow hot air around. Oddly enough you'll need to plug them into a wall socket to get them started. Because there is a fan blowing over the combustion chamber, it burns the fuel more efficiently and most of the horrible kerosene smells with it. Price wise, expect to pay around 10-12,000 for the most basic models and up to 40,000 for a high power model, with a large tank and features that reduce 'that' kerosene smell. Due to safety laws, all fan heaters must have a built in timer that will turn them off after 3 hours. Just listen for the alarm and press the appropriate button when the time is up.

Electric Heaters


Kotatsu are Japanese style heated tables that are indispensable on cold winters days. They have an infra-red heating element so that you won't burn yourself. There are 4 parts to a Kotatsu. An insulating mat that is placed over the tatami. Sometimes these are electrically heated as well. The under-side of the table has a low power heating element attached to it. A quilted cover that goes over the base and completely covers the sides. This keeps the warm air under the table. A solid table top that 'sandwiches' the cover between the table and the base.

All you do is place your legs under the kotatsu and enjoy the warmth. Kotatsu's are relatively cheap (starting from around 4,000 yen for the smallest basic models), however remember that you'll also need to purchase the kotatsu cover and mat as well. If the heating element on your kotatsu breaks down, replacement elements are available at most good denki stores.

Ceramic Heaters

These are the little ones that sit on your floor and blow out hot air. In Japan they usually draw between 800w and 1100w of power when operating at 'full steam'. Because they don't burn fuel to create heat, they are useful for those people who are sensitive to kerosene fumes or have respiratory problems. However, they are considerably more expensive to operate than kerosene heaters. Never operate this type of heater while sleeping.

Radiant Heaters

Very similar in design to the kerosene radiant heat, but they're powered by electricity than by a liquid fuel. If you prefer, they are also available in a design that closely resembles a 'fan'. This style has an element that can swing in an arc to evenly heat the room. Energy consumption is about the same as for a ceramic heater. Never operate this type of heater while sleeping. Once again, they are useful for those people who are sensitive to kerosene fumes or have respiratory problems.

Oil Column Heaters

As the name suggests, these are upright columns filled with oil and a heating element. These type of heaters take while to heat up to their operating temperature but come with a number of benefits. They are much safer than ordinary heaters because the heat is give off from the large surface area of the columns. This significantly reduces the fire/burn risk associated with this type of heater, and makes it a popular choice for families with young children. They are also often equipped with timers and thermostats, making this the ideal choice for people who wish to wake up to a warm apartment, or who wish to sleep while it operates.


Oil column heaters have earned a reputation of being more efficient than fan or radiant heaters. The reason for this is that once people turn them off, they keep on giving off heat, and they then assume that they're getting something for nothing. FALSE! This is nothing more than the residual heat being given off while the oil is cooling down. The same oil that took several minutes to heat up when you turned it on.

Oil heaters are especially popular in countries that charge a different rate for electricity at night than they do in the day. This allows people to heat their homes to comfortable temperatures prior to the expensive daytime rates kicking in. Since TEPCO (the local electricity supplier) charges the same uniform rate 24 hours a day, there is no benefit to be gained from doing this.


Some of you may be able to heat your apartments using your air-conditioners. If your air conditioner is marked with the words "Inverter" or "Reverse cycle", it means that it will operate backwards. Usually only the more modern air conditioner units will be able to do this. It will draw heat (energy) from the outside air and depositing it inside your apartment. Even though the outside air is colder than the air inside, it still contains substantial amounts of energy that can be extracted and used for heating.

Air conditioners are significantly more efficient than conventional heaters when operating in this way. The reason for this is that it is more efficient to move heat than to create it, and this is what an air conditioner does. On average they are in the range of 150-300% more efficient than conventional heaters depending on conditions. This means that they will draw about 1000 watts of power under normal use, but will give you the equivalent of 1500-3000 watts of heat output.

To add to this, many of these models have timers, thermostats, ionisers and a number of other features. They are also ideal for warming the house in the morning and for use while sleeping as they don't need supervision as most conventional heaters do.

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