# Post-Occupancy Evaluation in High-Rise Apartent Buildings in Vietnam
## 4 Conclusions  
This study provides a comprehensive analysis of indoor environmental quality, energy consumption, and occupant behavior in high-rise residential buildings in Hanoi, Vietnam, offering new insights into cooling patterns and their implications for building energy standards. The findings reveal that the assumption of \"full-time and full-space\" AC usage in current design standards overestimates cooling demand, as actual AC operation follows a \"part-time and part-space\" pattern. Electricity consumption for AC use peaks from May to September, while in the cold season, most surveyed rooms experience overcooling, highlighting the need to balance cooling and insulation strategies. Additionally, closing bedroom doors while using AC without proper ventilation poses risks to indoor air quality and occupant health, emphasizing the importance of adequate ventilation standards in residential building design. Building codes should incorporate realistic occupant behavior, ventilation strategies, and improvements in thermal insulation to improve energy efficiency and indoor comfort. For example, enhancing the building envelope through solar control glazing can help reduce heat gain while maintaining indoor comfort. Other passive design strategies, such as improved shading, controlled natural ventilation, and better insulation, should also be considered to optimize cooling demand while ensuring energy-efficient building operation. Given the dominance of mixed-mode cooling behavior, current energy efficiency standards should be updated to reflect actual AC usage patterns, preventing the overestimation of energy demand and allowing for more effective energy management policies. This study contributes to developing energy benchmarks for Hanoi's high-rise residential buildings by providing empirical data on occupant behavior, energy use, and indoor environmental conditions, supporting more accurate building energy performance assessments and policy recommendations. However, several limitations should be acknowledged. The sample size of 49 apartments in Hanoi may not have fully represented Vietnam's diverse housing stock, and while long-term measurements were conducted, more extensive statistical validation is needed. Additionally, caution should be exercised when applying these findings to regions with different climatic conditions, as occupant behavior, cooling demand, and ventilation strategies may vary across different climate zones. Future research should incorporate a more extensive and regionally diverse dataset, explore socio-economic influences on cooling behavior, and apply advanced statistical modeling to further quantify the relationships between occupant behavior, energy use, and indoor comfort. In particular, a socio-technical systems framework could provide deeper insights into how electricity pricing policies, family structure, and cultural preferences shape AC usage patterns. Future studies can refine energy efficiency policies, enhance building performance standards, and support sustainable urban development in Vietnam and similar hot-humid climates by expanding research in these areas. Y.W. : Methodology, Formal Analysis, Software, Data Curation, Writing--Original Draft, and Writing--Review and Editing. A.T.T. : Software, Formal Analysis, and Visualization. T.H.H.P. : Investigation and Writing--Review and Editing. T.H.N. : Investigation and Writing--Original Draft. K.S. : Writing--Review and Editing and Supervision. D.S. : Project Administration, Funding Acquisition, Conceptualization, Methodology, and Writing--Review and Editing. All authors have read and agreed to the published version of the manuscript. **Funding:** The present study received financial support from the Federal Ministry of Education and Research (grant number: 011Z1804). **Institutional Review Board Statement:** Not applicable. **Informed Consent Statement:** Informed consent was obtained from all subjects involved in the study.