(a) A household of a family consisting of a married couple in their forties and children living in a detached house

A married couple in their forties has two children and they live in a ten-year-old detached house (of their own) with three bedrooms.

This family has an air conditioner, electric refrigerator, lighting equipment and gas range, which the family bought at the time they built the house, as well as a television set, washing machine, electric clothes dryer, warmwater bidet, water heaters, etc., which the family bought later but is now considering replacing. Suppose the family is going to replace all of those appliances with up-to-date energy-saving models, and also replace existing window glasses with multiple-layer glasses that have high heat insulation performance in order to improve air-conditioning efficiency.

The resulting effects are estimated to be more 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 a nearly 150,000-yen saving of yearly utility costs (gas and electricity charges). Furthermore, as a result of the introduction of double-glazed window glasses, the family will enjoy reduced energy costs for their air conditioner as well as enhanced comfort from the avoidance of condensation nuisance.

## (b) A household of a married couple in their sixties living in a detached house

An elderly couple in their sixties lives in a ten-year-old detached house (of their own) with three bedrooms. Although the age and size of this house are the same as those of house (a) above, the operation hours of electric appliances and lighting equipment are different between households (a) and (b) due to the difference in their lifestyles.

Suppose this couple is going to replace their air conditioner, electric refrigerator and lighting equipment, as well as an old television set, washing machine, electric clothes dryer, warmwater bidet and water heater with the latest energy-saving models, and also replace existing window glass with multiple-layer glass that has high heat-insulation performance in order to improve air-

Figure 3-5-1: Changes in $ CO_{2} $ emissions as a result of the replacement of home appliances for the three households

The assumed electricity/gas consumption before the renewal is based on the industrial data on average general models of the relevant year of production. The assumed year of production is determined based on the results of the Consumer Confidence Survey conducted by the Cabinet Office on average life of electric home appliances, etc. Other technical data of electric appliances are based on information from The Japan Refrigeration and Air Conditioning Industry Association, final report by the Electric Refrigerator Evaluation Standards Subcommittee, Energy Efficiency Standards Subcommittee of the Advisory Committee on Natural Resources and Energy, information from Japan Electronics and Information Technology Industries Association, the handbook "Wa-no-Kurashi" (meaning "eco-life") published by the Ministry of the Environment and the handbook "How to choose and use energy-saving products" published by the Energy Conservation Center, Japan.

(*1) Guidelines for Measurement of Greenhouse Gas Emissions from Businesses issued by the Ministry of the Environment (July 2005)

(*2) Emission factor under the system of emissions calculation, reporting and announcement

Note2: The estimations are based on the assumption that the replacement takes place at a reasonable time for renewal. The purchase of the mentioned electric appliances can be estimated to require one million yen or more, and the renewal of water heater and window glasses is estimated to cost an additional 500,000 yen or so.