Japanese houses and apartments are well known for having little insulation, lots of drafts, and no central heating. Very little thought seems to be given to efficiently heating and cooling Japanese living spaces, at least outside of Hokkaido.

Typically each room will have it’s own heat pump based AC unit that is used for both heating and cooling. There will be a wall unit near the ceiling that is connected to a heat pump sitting outside. Rooms are heated or cooled individually and generally only when in use. Hallways, storage areas, bathrooms, etc are not heated or cooled in most Japanese houses.

In the summer the wall mounted AC units work relatively well since cold air falls and the wall units sit near the ceiling. In the winter though, things are not so good. Hot air rises so the air near the ceiling warms up very nicely while the bottom third of the room remains uncomfortably cold. Floors are often drafty and cold to the touch.

While little can be done about unheated hallways, storage rooms, and bathrooms there are some things that you can do to make your living areas more comfortable.

MAKE YOUR EXISTING AC UNIT MORE EFFECTIVE

If you are going to use your AC unit for heating there are a few things you can do to make sure you get the most heat for the lowest possible price.

If your AC is producing a musty smell then you need to get it professionally cleaned. Many small neighborhood electronics shops will provide this service, it generally costs 8000yen to 10000yen. The musty smell is from mold, it’s important to get the unit cleaned properly. They will also make sure the filters are clean and that the drain pipes are clear of blockage. Some people have their units cleaned every year but if you’re not running the unit 24/7 you can probably stretch the cleaning schedule to once every two years.

If you are not going to get the entire system professionally cleaned you should still clean the dust filters. Almost all wall units have two removable dust filters that you can access by opening the front panel of the AC unit. The filters will slide out, and if you haven’t cleaned them before, will probably be pretty clogged with dust. Generally it is no problem to wash these filters, just make sure they are completely dry before you place them back into the wall unit. AC makers will generally tell you that you need to clean the filters monthly but most people find that cleaning them at the beginning of winter and again at the beginning of summer is enough. If the filters are not clean then the AC will not be able to push enough air to heat or cool your room.

AIR CIRCULATION

This is an issue no matter what type of heating you use but it is especially important to consider if you use an AC unit mounted near the ceiling. Without effective air circulation the hot air will mostly accumulate at ceiling level (top 20% of the room) and remain there.

If you stand on a chair after running the AC for a few hours you will find that the ceiling air will be much warmer than the air in the bottom third of the room. Ideally this is solved by installing a ceiling fan in the center of the room but this is generally impossible in Japan due to lack of clearance and mounting difficulties. However you can use one of these fans instead. Place the fan on top of a shelf, ideally about 30cm from the ceiling, and aim the fan mostly upwards and slightly facing towards where you sit (you may need to experiment to find the optimal direction.) Set the fan on medium and it will be remarkably effective at pushing the warm air down from the ceiling and keeping the overall room temperature at a more even & comfortable level. If you can’t place the fan on top of a shelf then on a table will still help, but you may need to set the fan on high rather than medium. If you have a large room you may need a second fan.

HOT CARPET

Hot carpets are extremely popular in Japan and you will find them in most Japanese houses. Hot carpets are available in many sizes to fit most rooms and generally they aren’t actually a carpet but rather an electric heating pad that you place under an area rug. (You should only place them under an area rug that is designed for hot carpet use.) This Iris Ohyama hot carpet is available in the four most common sizes and the larger two sizes let you turn on only half of the carpet if you don’t need the entire area heated. If you have the space for it, the second largest size (2畳, 176×176cm) is the most commonly purchased. Generally the 176x176cm hot carpets are placed under a slightly larger 185x185cm area rug such as these ones.

KOTATSU

The next item many Japanese people buy to stay toasty in the winter is a kotatsu (こたつ). A kotatsu is a small table with an electric heater under it and a warm blanket or futon sandwiched under the table top. You sit with your legs under the kotatsu and can stay remarkably warm. If you often find yourself sitting on the floor anyway then a kotatsu will be a wonderful winter addition to your home.

Kotatsu come in various shapes and sizes and you can buy the tables and blankets separately or you can buy everything as a set. This Yamazen 75x75cm kotatsu set is a great option for singles or couples. If you need a bit more space there are larger choices like this 120x80cm option.

KEROSENE (灯油) HEATER

Electricity in Japan is quite expensive so many households opt to heat living areas with kerosene heaters instead of using AC units. This is the most cost effective way to heat your living area, but of course it comes with some caveats:

  • You *MUST* make sure to have some ventilation or you may find yourself experiencing headaches, an early sign of carbon monoxide poisoning.
  • You should never heat a sleeping area with kerosene. If you don’t have proper ventilation and/or something goes wrong with the heater (rare but not impossible!) you may never wake up.
  • You must exercise proper care when refueling the heater. Never refuel a hot heater and never refuel when the heater is operating.
  • Only use kerosene in your kerosene heater. This is perhaps obvious but there have been cases of people trying to use gasoline or other fuels. This generally results in a fire and/or explosion.
  • Any room that is heated with kerosene should also have a carbon monoxide detector. These are relatively inexpensive and some (like this one) even give you a CO level PPM readout.

Don’t let the above caveats put you off using kerosene though! Kerosene heaters produce a very comfortable heat and will quickly warm up even a really cold room. Rooms heated with kerosene also usually have a higher relative humidity which is both more comfortable and helps keep static electricity levels under control.

One of the most popular kerosene heaters right now is this unit by Corona. It’s made in Japan, is priced competitively, and has quite a high heat output. You should also purchase a carbon monoxide (CO) detector such as this one, and you will need an approved can to store kerosene. Many people buy two cans so they have some fuel in reserve. Finally it will be much easier to refuel your heater if you purchase a small hand pump. Some people opt for more complicated battery powered pumps but they’re quite a bit more expensive and the hand pumps work just fine.

As far as where to buy kerosene, most gas stations will sell it. Kerosene is also delivered door-to-door in Japan, the truck will drive around playing a loud & distinctive tune that you’ll soon learn to recognize. You’ll pay a bit more for home delivery but it saves the hassle of having to carry 18L cans of kerosene from the local gas station.

ELECTRIC BLANKETS

If you find yourself sitting for long periods of time at work or at home you may find an electric blanket provides a lot of warmth for a very low cost. This one is very popular due to the low price, being washable, and having a sliding temperature adjuster. It’s great for draping over your legs while sitting in a chair!

Using an electric blanket on your bed can be a good way to stay warm in the winter as well. For optimal performance you will need to sandwich it between two other layers and you will want a larger size blanket like this one. When using an electric blanket you will probably be able to sleep without heating the room thus saving quite a bit on your heating bill over the course of a winter!

COLD FEET

If you’re at home the very best solution to keep your feet warm is a good kotatsu. However if you’re at work or just working at a desk at home a kotatsu isn’t a practical solution.

There are mini hot carpets sold specifically for keeping your feet warm such as this one. They can be as small as 40x40cm but I generally prefer the 50x50cm or 60x60cm ones.

The other obvious answer (for home at least) is a good, warm pair of slippers. The problem is that most slippers really aren’t that warm and they constantly slip off your feet. If you’re Canadian then you should grab some MEC Hut Booties. They are super warm and have a soft non-slip sole that will be fine to wear indoors. If you’re not in Canada it is possible to have MEC ship them to Japan but Canada Post shipping is unreasonably expensive. REI in the US also has a selection of warm booties and their international shipping options are probably less expensive. You may also find booties at outdoor stores in Japan but if you have larger feet you may have issues finding options in your size.

Stay warm everyone!

-i