households in Japan is projected to peak in 2015 and then decreases; the upward trend in the number of households is estimated to continue until then (“Household Projections for Japan” issued by the National Institute of Population and Social Security Research in March 2008). As the number of households will continue to rise for some time, we must reduce the energy consumption per household in order to limit residential energy consumption.

Let us look at the other three countries. In the United Kingdom, the final energy consumption increased slightly (12%) and the residential energy consumption has increased 16% from the base year. However, compared to the rates of increase in economic indexes such as the GDP (43% increase) and household spending expenditure (50% increase), the rate of increase in energy consumption is relatively small.

In Germany, the residential energy consumption in recent years is approaching the level of the base year.

In the 1980s in the United States, along with the annual increase of 0.16% in the final energy consumption, the residential energy consumption also increased at a similar rate. This is due to the fact that the high cost of energy resulting from the oil crises kept fuel consumption, mainly petroleum, at a steady level, and that the per-household energy intensity improved. However, lower oil prices and brisk economic growth in the 1990s greatly boosted the energy use including the residential energy consumption.

## 3 Residential Energy Consumption Based on Different Usages

The composition of residential energy consumption in the world differs depending on climate, living standard, lifestyle, and culture. Here, we review measures taken by different countries to improve the per-household energy intensity, with focus on the usages of energy in household.

Figure 2-2-4 Changes in Per-Household Energy Consumption by Usage in Selected Countries

Note: Electrical appliances & lighting, etc.: TV sets, refrigerators, personal computers, etc.

Cooking: heat sources for cooking, etc.

Water heating: bath, shower, etc.

Space heating & cooling: air-conditioners, heaters, etc.

Source: Compiled by the Ministry of the Environment from the data of Enerdata, Odyssee Database (March, 2008); IEA, Energy Balances of OECD Countries 2007; US-EIA, Annual Energy Outlook 2004; The Institute of Energy Economics, Japan, 2008 EDMC Handbook of Energy & Economic Statistics in Japan; and others

As shown above, the per-household energy consumption in Japan is lower than in other western developed countries.

Japan’s per-household energy consumption by usage in 2006 shows that 35.1% was used for power/lighting, etc., 31.2% for hot water, 23.7% for heating, and 7.9% for cooking, and 2.2% for air-conditioning. The national average shows that most of the energy consumed was for household electrical appliances and hot water. In comparison, the United Kingdom and Germany have extremely high energy consumption for heating (Figure 2-2-4).

The per-household energy consumption for heating in the United Kingdom and Germany is over three times that of Japan, and this is the major cause of difference among the countries in per-household energy consumption. Although the need for heating differs depending on the winter temperature, different heating systems also account for the difference in energy consumption. In western countries, many buildings are heated constantly using a central heating system.

## (1) Measures to Improve the Energy Efficiency of Buildings

## A Measures in the EU

Since a great part of the residential energy consumption in Europe is for heating, household energy conservation measures place an emphasis on insulating buildings to improve energy efficiency. Because central heating is an integral part of the building and is very common in Europe, improving heating efficiency must be carried out as part of building renovation, rather than just replacing individual devices. Most buildings were built a long time