Factor X (eco-efficiency) assessment on global warming a household in Japan

Taeko Aoe, Ryoichi Yamamoto, Toshiharu Ikaga, Yasushi Kondo, Yuichi Matsuoka, Moriki Fukuda

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)


This paper proposes a new method for evaluating the eco-efficiency of a household based on Factor X, which was proposed by Yamamoto and colleagues in 1999. We had proposed methods for evaluating Factor X of a household which consists of a building and home appliances, and implemented empirical evaluations. However, there remained the following two issues to be considered. One is how to quantify the function of a household. The other is how to take account of the so-called synergy effects. It proposes the method for calculating the overall functions of one household using the purchasing price as a weighting coefficient. This method is the same as Laspeyres quantity index in economics fields. As a synergy effect, the insulating effect in the building, etc. are considered. The result showed that the annual greenhouse gas emission of a typical household drastically decreased by 52.2% from 1990 to 2009 while the aggregated function of the household slightly decreased by 0.2% during the same period so that Factor X was 2.1 with respect to global warming. It was thus shown quantitatively that Factor X of households in Japan presumably improved during the period although only limited assessments were implemented.

Original languageEnglish
Pages (from-to)1070-1087
Number of pages18
JournalNihon Enerugi Gakkaishi/Journal of the Japan Institute of Energy
Issue number11
Publication statusPublished - 2010


  • Eco-efficiency
  • Factor X
  • Global warming
  • Household

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Fuel Technology
  • Energy Engineering and Power Technology


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