relatively short period of time and include the installation of an inverter to introduce variable air-volume control for air-conditioning systems, the installation of an inverter to introduce flow control of coolant and hot and cold water for pumps, the installation of high-efficiency lighting system, and the installation of a total heat exchanger for recovery of exhaust heat and air. The calculation result is about a 27% reduction of $ CO_{2} $ emissions in a year (equivalent to about 236 tons) (Figure 3-5-3).

Building conditions are diverse and appropriate energy-saving measures and the resulting effects vary according to the buildings. However, as shown by the above estimations, a considerable amount of energy conservation can be achieved through the introduction of low-cost, currently available energy-saving technologies to existing facilities and equipment, without any building reconstruction.

As mentioned above, it is possible for homes as well as buildings for business use to achieve relatively large effects of $ CO_{2} $ emission reduction in a relatively short period of time by introducing currently available energy-saving technologies. (It

Figure 3-5-3: Potential $ CO_{2} $ emission reduction expected from introducing energy-saving measures to a building for business use.

Note: The estimations are made by using the “management tool for intensity of energy consumption” of the Energy Conservation Center, Japan

Source: Ministry of the Environment

## Column : An Example of the Successful Introduction of Energy-Saving Measures to a Building for Business Use

Energy-saving technologies or measures to be introduced into buildings for business use should be cost-effective in terms of initial investment as well as expected reduction of running costs after the introduction. ESCO programs are being inaugurated in support of the increasing number of measures with significant energy-saving potential (See the Column in Section 4).

Recently, an energy-saving project was carried out under the ESCO program for a building (hereinafter referred to as “Building X”) located in the Tokyo metropolitan area (with six stories above ground and a total floor space of about 47,000 square meters).

The project included the renewal of a freezer and a water chiller/heater, the installation of an inverter, the introduction of a new control system for air conditioners and the introduction of BEMS. As a result of the project, this building succeeded in reducing $ CO_{2} $ emissions by about 15%.

It is known that the introduction of the cogeneration system is quite effective especially for large-sized buildings such as hotels that have a large thermal demand. Many of those buildings are reported to have achieved as much as a 20% reduction in $ CO_{2} $ emissions through the introduction of the cogeneration system.

Table 3-5-1: Energy-saving measures introduced to Building X

Renewal of heat source equipment to introduce high-efficiency models	Two water chiller/heaters have been replaced with a high-efficiency turbo-freezer and two high-efficiency water chiller/heaters, and quantity control has been introduced.
Introduction of the DDC (direct digital control) system to air-conditioners	PMV control system (that ensures user comfort while controlling and conditioning), the control system for outdoor-air intake for indoor cooling, CO $ _{2} $ control system and the on/off control-optimization system have been introduced.
Introduction of an inverter to fans	Fans in which inverters are installed have load-corresponding air volume.
Introduction of an inverter to pumps	Water pressure optimization has been introduced for the secondary water supply system with the introduction of a pump inverter for hot and cold water and coolant. Flow control has been introduced for the primary hot and cold water and coolant.
Introduction of BEMS	BEMS, which monitors two buildings simultaneously, has been introduced to enhance integral energy control.
Introduction of high-efficiency lighting equipment	A total of 2,000 fluorescent lights and downlighters have been replaced with newer models.

Source: “Implementation Examples of the ESCO Projects” issued by the Energy Conservation Center, Japan (ECCJ). Compiled by the Ministry of the Environment.

Turbo freezer and water chiller/heater Photo: courtesy of ECCJ