Investigation of Toilets with Reduced Ventilation Frequencies and Odor Simulation

M. Kimura, T. Akimoto, S. Kato, N. Hirasuga, Y. Sakamoto, S. Yamakita, H. Sakakibara

Research output: Contribution to journalConference articlepeer-review

1 Citation (Scopus)


For a sustainable society, we must consider how to reduce the CO2 emissions from buildings; however, the ventilation frequency in the toilet (i.e., bathroom or water closet) has not been changed in recent years. Only a few attempts have been made so far to reduce the ventilation frequency in toilets to save energy, despite their further technological developments. In this report, we considered evacuating the odor as soon as possible by providing an exhaust port at the bottom of the wall (hereinafter referred to as baseboard deodorization). We also considered the effect of baseboard deodorization for different toilet (bathroom) sizes. First, we surveyed the relationship between the odor detected by a sensor and a human's olfactory sense and the ventilation volume with the toilet in operation to verify the usefulness of the sensors. Secondly, we analyzed the air environment using computational fluid dynamics (CFD). The results of the measurements and a questionnaire survey showed a certain degree of correlation between the indication of the degree of contamination in the air and the odor intensity. The results of the CFD analysis indicated that large-scale toilets could accumulate air more easily than small toilets; however, in either case, the ammonia concentration could be lowered by using baseboard deodorization. It was also found that the exhaust from baseboard deodorization greatly contributed to reducing the ammonia concentration.

Original languageEnglish
Article number012046
JournalIOP Conference Series: Earth and Environmental Science
Issue number1
Publication statusPublished - 2019 Aug 9
EventSustainable Built Environment Conference 2019 Tokyo: Built Environment in an Era of Climate Change: How Can Cities and Buildings Adapt?, SBE 2019 Tokyo - Tokyo, Japan
Duration: 2019 Aug 62019 Aug 7

ASJC Scopus subject areas

  • Environmental Science(all)
  • Earth and Planetary Sciences(all)


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