## 5 Conclusions  
Through the analysis and verification of perception evaluation experiments combining one-dimensional and two-dimensional scales and appropriate length selection experiments combining three-dimensional scales, data were obtained on the optimal appropriate length range and scale combination for underground commercial streets. Through the one-dimensional and two-dimensional scale combination of perception evaluation experiments and the three-dimensional scale combination of appropriate length selection experiments of data testing and analysis, the best underground commercial street was finally obtained with an appropriate length range and scale combination of data with a width of 3.3 m, an experimental height of the value of dimensions of 3 m, and an appropriate length range of about 43-46 m. When the experimental height was 3.5 m, the appropriate length range was about 37-41 m; in the underground commercial street with a width of 5.4 m, when the experimental height was 3.0 m, the appropriate length range was about 62-66 m, and when the experimental height was 3.5 m, the appropriate length range was about 58-63 m. When the experimental height was 4.0 m, the appropriate length range was about 49-53 m. When the experimental height was 5.0 m, the most appropriate length range was about 46-52 m; compared with other widths, the spatial perception of the underground commercial street with a width of about 5.4 m generally reached an appropriate state within the appropriate length range, indicating that this value should be used as the recommended width of the underground commercial street; in the underground commercial street with a width of 8.7 m, the experimental height was 5 m, and the most appropriate length range was about 60-65 m. In the perception research of underground commercial streets, experiments have been conducted to derive eight sets of three-dimensional scale combinations that can provide the most comfortable feeling. The relationship between the appropriate width-to-height ratio of an underground commercial street and the overall perception of its space can be summarized as follows: a more appropriate ratio will result in a higher overall perception of appropriateness and a more extensive range of appropriate length options. The variation pattern of the appropriate range of three-dimensional scale combinations is as follows: when the width is 3.3 m, the appropriate length range will initially decrease and then increase with the increase in height; when the width is 5.4 m, the appropriate length range will gradually decrease with the increase in height; when the width is 8.7 m, the appropriate length range will also gradually decrease with the increase in height. Conceptualization, T.Y. and Y.Z. ; data curation, S.D. and X.X. ; formal analysis, X.C., Z.L. and Y.H. ; funding acquisition, L.S. and Z.L. ; investigation, L.S. ; methodology, T.Y., Y.X. and K.H. ; project administration, Y.H. and J.W. ; resources, L.S. ; software, X.C., Y.X. and K.H. ; supervision, T.Y., Y.Z. and L.S. ; validation, S.D., X.X. and J.W. ; Visualization, T.Y. ; writing--original draft, T.Y. and Y.Z. ; writing--review and editing, S.D. and Y.X. All authors have read and agreed to the published version of the manuscript. This study has been financially supported by \"International Science and Technology Cooperation Fund of Jiangsu Collaborative Innovation Center for Building Energy Saving and Construction Technology (grant no. SJXTGJ2102)\" and funded by \"the Graduate Innovation Program of China University of Mining and Technology (Grant No. 2023 WLJCRCZL315)\" and \"2023 Funded by the Postgraduate Research and Practice Innovation Program of Jiangsu Province (Grant No. SJCX23_1270)\". The original contributions presented in the study are included in the article, further inquiries can be directed to the corresponding author. Author [PERSON] was employed by the company China United Engineering Corporation Limited.