The development of underground transport hubs has become an important approach to address urbanization problems such as heavy traffic and land deficiency. Top openings in the underground transport hubs can enhance underground daylighting and natural ventilation. However, the underground space will receive more solar radiation through top openings, where a thermally uncomfortable environment would be formed on summer days. It is necessary to understand the relationship between opening design parameters and thermal environment index, so as to assist the designers to improve design proposals. This study proposed an analytical method to evaluate the thermal environment based on sunshine hours. This method can qualitatively and quantitatively analyze the distribution of sunshine hours in the analyzed underground space using a sunshine simulation tool. Hourly variation of solar radiation intensity is also considered through the weight analysis method. The relationship between opening design parameters (i.e. opening rate, number of openings, underground space height) and sunshine hours has been discussed in this study. An underground transport hub located in Guangzhou is selected as a case study object to demonstrate the application process of the proposed method. The results show that the proposed method can assist the designers to determine top-opening design proposals with better thermal environment and lower building energy consumption for underground transport hubs at the scheme design stage.

Public buildings such as libraries consume a vast amount of cooling energy for maintaining a comfortable and stable indoor environment in summer, especially in the hot-humid climate. This study used a case study approach to discuss the effect of low-energy strategies that can be applied to improve indoor thermal environment and cooling energy consumption of library buildings in hot and humid cities like Nanning City (a southern city, China). The use of cooling window shutters (a shutter with the effects of shading and evaporative cooling) and ceiling fans for generating airflow was considered as applicable energy-saving measures in this study, and a university library was selected as the study building in which the two energy-saving measures were employed. The SET* and annual cooling load before and after the adoption of the proposed measures were quantitatively investigated with a building energy consumption simulation software (DesignBuilder). Simulation results showed that the daytime SET* values can be reduced by 3.0 °C and 4.5 °C respectively on a typical summer day after the use of the cooling shutters and ceiling fans. Moreover, the cooling loads can also be decreased by 8.4% and 16.6% respectively. Particularly, the combination of these two measures enabled the daytime SET* value and annual cooling load lower by 7.0 °C and 60.8% respectively.