A Simultaneous Usage Ratio Based on Occupant Behavior: A Case Study of Intermittent Heating in an Apartment Building in Japan

It is important to reduce the building load and downsize the heat source equipment capacity during construction or renovation carried out toward the achievement of carbon neutrality by 2050 in Japan. However, this sometimes results in the oversizing of the heat source equipment capacity, despite the fact that designers are engaged in the implementation of safety designs while attempting to balance between cost and risk. This study investigated the simultaneous usage ratio of heating based on occupant behavior in an apartment building with the aim of optimizing this capacity. This ratio was defined as a peak load-based approach rather than simultaneity based on the number of people using the system. First, the analysis was conducted for the heating load characteristics for each dwelling unit and each household composition. The subject of this case study was an apartment building located in Sapporo, Japan. Based on these data, a method for creating the curve of the simultaneous usage ratio to avoid a combinatorial explosion was suggested. As a result, the ratio created for about 200 dwelling units was 53.6% in an apartment building and generally stabilized when the number of dwelling units exceeded 30. Finally, a case study was attempted to analyze the influence of changes in household composition on the ratio. If the method proposed in this study for creating the curve of simultaneous usage ratios were to be applied in not only this case study but also in case studies of non-residential buildings such as offices, new results about the curves of ratios that differ from those of apartment buildings could be obtained. Therefore, this case study provides a methodology for statistically quantifying the simultaneous usage ratio as one of the factors in determining the appropriate heat source equipment capacity in the design stage.

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