In 2000 we moved into an apartment in Tokyo run by the semi-public housing corporation UR. It was new and had a natural-gas heating system. Unlike other gas systems we’d used in the past, however, this one heated water that was then circulated to outlets in different rooms in the apartment. Direct gas ignition devices we’d bought for previous apartments were useless in our new one so we had to get rid of them and buy special stand-alone devices from Tokyo Gas that connected to these outlets. When we moved out of the UR apartment several years ago we also had to throw those away because our new apartment, also run by UR, had a different heating system and Tokyo Gas has no buy-back program.

Central heating is not as widespread in Japan as it is in other developed countries. Heating an entire house or apartment uniformly is considered wasteful since all rooms are not necessarily going to be occupied at the same time, and energy prices in Japan have always been high. Heating a residence is done in a component fashion, with each room having its own discreet heating device. The rationale behind this has proved to be lucrative for Japanese utilities and home-appliance makers. With central heating, any improvements are made through maintenance and repairs, but with a component system, they are made through replacement, which can happen fairly often if technology improves over time.

But a component system can also be wasteful. Heating devices that are constantly being discarded have to be recycled, otherwise they simply end up as landfill. And component heating is not going to be any more energy efficient than central heating if a residence isn’t airtight and properly insulated.

There are many options for heating a home, and selecting the one that’s best for yours depends on your circumstances. If you are renting, you usually don’t have a choice. But if you can afford to be selective, it pays to understand what different heating systems offer, since many new rental apartments utilize systems other than conventional gas outlets. And if you’re buying or building a house, it’s important to know what you need.

There are two basic methods of indoor heating: air circulation and radiation. With the former, air is heated and then sent throughout a given space by means of a fan. The latter releases infrared energy to heat objects and surfaces in a given space. Circulation heats a room quickly, while radiation takes longer. Circulation makes more sense in homes where rooms are occupied intermittently during the day, while radiation is better when a home is being used more or less continuously. Circulation heaters include wall-mounted air conditioners and gas or kerosene-powered fan heaters. Radiation heating methods include floor heating, panel or coil heaters and storage heaters.

Experts agree the most efficient device for home heating is the wall-mounted air conditioner, which is now present in more than 85 percent of Japanese homes, with the average household owning 2.5 “aircons.” Most people buy aircons for their cooling function, since that is how they are marketed. Almost all use the heat-pump principle, which transfers ambient energy in whichever direction the function requires. Heat pumps do not convert potential energy into heat and so they use less source energy, which is only used to operate the system.

In February 2012, the Asahi Shimbun ran an article about a family of six in Chiba Prefecture who, on the advice of an “energy adviser,” stopped using kerosene heaters as their main means of heating. The family had been purchasing two or three 18-liter containers of kerosene every 10 days, spending on average ¥11,000 a month. The advisor told them to use air conditioners for heating, and they stopped buying kerosene.

The family’s monthly electricity bill rose by ¥1,500, but since they weren’t buying any kerosene they were saving ¥9,500. What’s interesting is that the family already had air conditioners installed in their home for cooling purposes, but because the media tend to harp on the amount of energy used in the summer for air conditioning, they thought it would be better to use other sources for heating.

That perception of air conditioners being expensive to run could be because while there are many options for heating homes, there is only one for cooling. In fact, much more electricity is used to heat homes in the winter than is used to cool them in the summer. Though energy use surges when the unit is turned on in a cold room, once it reaches the optimum temperature it stays at that level using much less power. And now, air conditioners come with heat sensors that determine areas in a room that are not sufficiently warm, and then adjust the strength and flow of air accordingly.

Still, many people don’t use air conditioners for heating because they don’t like the feeling of hot air moving over their skin. Then there are aesthetic considerations — the big white box on the wall and the even bigger fan unit outside with all its unsightly connecting tubes. They can be noisy, too. More significantly, however, they are not suitable for very cold climates since heat pumps don’t work as efficiently when the outside air falls below a certain temperature. In Hokkaido, for example, floor heating and storage heaters are more popular, and now along the Japan Sea coast, these methods are becoming more common in new homes.

Floor heating can use a variety of sources: electricity, gas, or water heated by gas or kerosene. Unlike air conditioners, floor heating produces no dust or noise and there is no need to clean filters. There are no devices hanging off the wall or taking up space on the floor. It is also virtually maintenance-free. The main drawback is the high initial cost, since the system has to be installed in the structure of the residence. In most cases, special flooring material is necessary, and the layout of a residence will affect how efficient the system will be.

It also takes time for floor heating to warm a cold room, which is one of the drawbacks of storage heating, another option that’s becoming more popular. The main merit of storage heating, however, is economy. In the long run it can be even cheaper than air conditioning, and since it is designed to be kept on continuously, quick warming is not an issue for most users. Electricity is used to heat a mass of material, usually bricks or other ceramics, and then the collected heat is released over time. It’s economical because energy is collected in the middle of the night, when electricity costs are less than half what they are in the daytime. The drawback is their large size and weight — floors need to be reinforced before a storage-heating unit is installed. Depending on the layout of a house, however, a single unit can comfortably heat an entire story. Some systems even utilize the home’s foundation and the soil beneath it as storage medium.

Renters and owners of older homes may have no choice but to use space heaters, whether gas, kerosene or electric-powered. Their only merit is that they heat areas quickly if they come with a fan. They are expensive to run and, more significantly, potentially dangerous, since gas and kerosene produce flames as well as carbon monoxide. Every year a dozen or so people throughout Japan die from house fires or carbon-monoxide poisoning due to faulty or superannuated “stoves,” as they’re often referred to here. Even if you have a new gas or kerosene heater, you must open a window every so often to get rid of the bad air, an action that defeats the purpose of a heater.

Philip Brasor and Masako Tsubuku blog about Japanese housing at www.catforehead.wordpress.com.

Heating by numbers: Comparing the circulation methods

The average costs of heating one room for one hour using circulation method depends on the kind of energy used.

• Electric air conditioner: ¥14

• Kerosene-powered fan heater: ¥31

• Gas-powered fan heater (equivalent): ¥45

• Electric-powered fan heater (equivalent) : ¥70

Source: “Support for Climate Change Action Handbook”

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