conditioning efficiency.

The resulting effects are estimated to be slightly less than a two-ton reduction in $ CO_{2} $ emissions per year. This is about a 40% reduction in emissions when compared to the emissions before the replacement, and is equivalent to more than a 100,000-yen saving of yearly utility costs.

## (c) A household of a single male in his thirties who is getting married soon and is currently living in a rented apartment

A single male in his thirties is getting married soon. Upon marriage, he is going to move to a rented apartment with one bedroom, from the current one-room rented apartment that he moved into ten years ago, when he first started his current job. Suppose he is going to replace all of his electrical appliances with up-to-date energy-saving models when he moves.

Figure 3-5-2: Effect of $ CO_{2} $ emission reduction through the replacement of a conventional car with a new model

Note: The estimations are based on the assumption that a 1500cc-gasoline vehicle is replaced with a hybrid vehicle of the same size. For the estimates, the 10.15-mode fuel consumption is applied.

Source: Ministry of the Environment

The new refrigerator, television set and washer-and-dryer laundry machine he is going to buy will all be bigger in size than the current ones. Furthermore, his household will be upsized from a single to two. Still, however, $ CO_{2} $ emissions in his new household can be estimated to be possibly lower than the present, thanks to the high-efficiency models.

Figure 3-5-1 shows the summary of the estimations for the above three households.

### b. Replacing a private car with a high-efficiency model

Now let’s see how much $ CO_{2} $ emission reduction can be expected from the replacement of an existing conventional car with a new model that has excellent fuel economy.

The amount of $ CO_{2} $ emissions to be generated by the use of a car greatly depends on the way it is driven and on traveling distance. A traveling distance varies significantly among households. Figure 3-5-2 shows four examples of different traveling distances.

## (2) Simulative analysis of the potential $ CO_{2} $ emission reduction that can be expected from the introduction of energy-saving technologies to a building for business use

Now, let’s figure out the potential $ CO_{2} $ emission reduction that can be expected from the introduction of currently available energy-saving technologies to existing buildings for business use. Two examples follow: the first one represents the case wherein operational optimization is thoroughly introduced to existing facilities and equipment and the second one represents the case wherein moderate capital investments are made to introduce energy-saving measures in addition to the said optimization. Here, the capital investments are limited to those that are expected to pay off in a relatively short period time, such as a replacement of conventional lighting equipment with new models. The building concerned is assumed to be an average construction located in Tokyo (with eight stories above ground and one below, having the total floor space of about 7,500 square meters).

### a. Introducing the thorough operational optimization to existing facilities and equipment

The potential $ CO_{2} $ emission reduction effects that can be expected from the introduction of operational optimization, such as outdoor air-intake control, use of outdoor air for indoor cooling, etc. has been figured out based on the assumption that existing facilities and equipment, such as air conditioners, pumps, heat source equipment, lighting equipment, power outlets, water heaters, water supply systems, drainage systems and elevators, continue to be used. The result is about a 2.6% reduction of $ CO_{2} $ emissions in a year (equivalent to about 23 tons) (Figure 3-5-3).

### b. Introducing capital investments to major facilities and equipment

The potential $ CO_{2} $ emission reduction effects that can be expected from the introduction of capital investments in addition to the optimization as mentioned above has been figured out. Here, the capital investments are limited to those considered to pay off in a