Abstract：[Objective] Existing design standards for energy efficiency impose rigorous static restrictions on the shape coefficient and envelope performance of buildings. However, these requirements are incompatible with dynamic adjustment to real-time changes in the weather. Thus, the loss of energy-saving effect and indoor use quality of the building proffers the potential for improvement. Therefore, this study introduces the south-oriented combined external window design for buildings based on the principle of leap heat transfer. This design improves the solar heat gain during the daytime and the insulation performance at night, which is a feasible strategy to dynamically improve the indoor thermal environment and reduce the building load. However, the effect of this design strategy on the Tibetan plateau region still needs further investigation. To improve the energy efficiency and indoor usage quality of office buildings, this study takes a typical office building in Xigaze as the object to explore the more suitable design strategies for south-oriented external windows. [Methods] This study compares nine building cases with distinct south-oriented external window designs. By quantifying the differences in building performance induced by each window design, the most efficient south-oriented external window design in the Tibetan plateau region is identified. The triple-glazing low-E windows in the baseline case meet the thermal performance requirements. In the rest of the design cases, the external window components consist of a 6 mm glass curtain wall with heat-break bridge aluminum alloy, a normal insulating window or low-E insulating window composed of two pieces of 6 mm glass and 12 mm air interlayer, and an insulating cotton curtain. DesignBuilder 6.1 is used in this study to analyze the cool and heat loads, hourly operating temperature, and thermal comfort of the primary rooms in a dynamic simulation throughout the year. Consequently, the comparison of the performance scores of nine building cases serves as the foundation for case validation. [Results] The results indicate the followings: (1) In the absence of heating and air conditioning, the indoor operating temperature fluctuates less in summer and more in winter. (2) In the absence of heating and air conditioning, the average time percentage of indoor temperature (from 18 ℃ to 26 ℃) varies significantly depending on various types of windows. The dynamically adjustable external window allows for a longer period of comfort in the office and a relatively long period of comfort in the dormitory. (3) The combination of a 6 mm glass curtain wall with heat-break aluminum alloy, normal insulated windows consisting of two pieces of 6 mm glass and 12 mm air interlayer, and thermal insulation curtains presents the lowest heat load and total load in the design case. (4) Compared with the baseline case, the proposed external window design enables a higher level of annual thermal satisfaction and indoor thermal sensation. [Conclusions] For office buildings in the frigid plateau region, glass curtain walls and heat-collecting walls should be used to fully capture solar radiation during the daytime. Meanwhile, thermal insulation should be employed to reduce heat dissipation at night. The proposed external window design presents the most significant effect on reducing building load and improving thermal comfort. Moreover, compared with windows employing low-E glass, this design reduces the construction cost and can be considered a more efficient choice for the south-oriented external window design of office buildings in the frigid plateau region.
刘依明, 许沛琪, 刘念雄. 高寒地区典型办公建筑南向组合式外窗热工设计优化[J]. 清华大学学报（自然科学版）, 2023, 63(11): 1878-1886.
LIU Yiming, XU Peiqi, LIU Nianxiong. Thermal design and optimization of south-oriented combined external window for a typical office building in frigid plateau region. Journal of Tsinghua University(Science and Technology), 2023, 63(11): 1878-1886.
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2023, Vol. 63 
