資本財のリユースを考慮した温室効果ガス排出量算定方法の改善方法の考察

抄録

Objective. The objective of this study is to propose an optional calculation method for category 2（capital goods）of GHG Protocol Scope 3 Standard^1） for the manufacturing industry.

Results and Discussion. The Technical Guidance of Scope 3 Standard^2）does not describe the calculation method concerning the cases of selling capital goods or buying second-hand capital goods. Using the approach toward recycled materials described in Category 5, we explored a method of calculating Category 2 emissions for cases involving second-hand capital goods. As a result, we concluded that avoided emissions associated with reusing can be optionally counted in the calculation by subtracting the value of emissions based on the selling price when the product is sold second-hand. Purchasing/Selling prices of capital goods are indicated in cashflow statements. In purchasing capital goods, Category 2 emissions are calculated based on the purchasing price, and the emissions according to the remaining value（selling price）will be subtracted when being sold. This method is reasonable in that the buyer of the second-hand goods calculates Category 2 emissions using this subtracted value（i.e. purchasing price）which is regarded as the remaining amount of upstream emissions corresponding to the economic value of those second-hand capital goods at that point. In this way, Category 2 emissions relating to second-hand capital goods can be calculated easily.

Conclusions. The current work showed avoided emissions of capital goods associated with reusing should be counted in the calculation by subtracting the value of emissions based on the selling price when the capital goods is sold second-hand.