Dian Zhou

This study aims to evaluate the comprehensive potential of cooling strategies in an old urban block in Xi’an, China, where the outdoor environment requires significant improvement. The Luomashi block is chosen as a case study. The strategies include cool pavement (CP) and facade (CF), green facade (GF) and roof (GR), tree-planting (TP), water fountain (WF) and mist (MR), and their combinations. The results show that most of the individual strategies can reduce the canyon air temperature and the physiological equivalent temperature (PET) at the pedestrian height of 1.5 m throughout the day. The combination of CP, CF, CR, TP, WF, and MR (CC1) can reduce the daily N–S and E–W canyon air temperatures by 1.4 °C and 1.0 °C, respectively. For the combination of CP, GF, GR, TP, WF, and MR (CC2), the reductions are 1.4 °C and 1.1 °C. Meanwhile, these two combination scenarios can reduce the daily mean PET by 2.71 °C and 2.87 °C, and reduce the daily cooling energy demand by 8.4% and 8.9%. The exploratory findings reveal the site-specific cooling potential of these particular mitigation configurations within the historical fabric of the Luomashi block, highlighting that the performance is highly dependent on the chosen baseline parameters and local morphological constraints.

Pocket parks, the green infrastructures with small sizes and flexible layouts, are suitable for thermal environment improvement in the urban built-up block with limited green space. To quantify the relationship between pocket parks and the thermal environment in western China, two parks in the built-up block of Xi’an were selected. By field measurement, the cooling effect could be extended 100 m from the park boundary, connecting two parks. Furthermore, the road and greening within the block demonstrate significant influence on the cooling diffusion by regression analysis. Based on ENVI-met simulation, the ratio of the tree and the grass, the layout of the tree and the grass, and the layout of the paving were analyzed at different proportions of greening and paving of the park. Finally, a combination of the daytime physiological equivalent temperature (PET) and nighttime air temperature (AT) was proposed to choose the optimum layouts: the trees concentrated in the center and the pavement with more roads. Results can provide insights for designing pocket parks based on the thermal environment improvement.

During the process of the high-speed urbanization in Chinese cities, the social, economic, and political status and the interaction between each factor have been more focused on urban traditional district renewal. However, the effects on urban microclimate and the residential living conditions in traditional districts are not well discussed, which is strongly related to the living comfort and citizens’ well-being. In this study, two typical traditional districts in Xi'an are selected. According to the original situation of building functions and the community characteristics, two renewal plans are proposed by adding vegetation in open spaces (V), and adding vegetation combined with building redevelopment (V&B), in order to balance the living convenience and thermal environment. Via ENVI-met simulation, the effects of the district renewal plans on thermal environment including wind speed, air temperature, and mean radiant temperature are evaluated. This study provides method of environmental evaluation for traditional district renewal, which contributes to sustainable urban planning in historical districts, and provides recommendations for related policy development.

Pocket parks, the green infrastructures with small size and flexible layout, are suitable for thermal environment improvement in the urban built-up block with limited green space. To quantify the relationship between pocket parks and the thermal environment in western China, two parks in the built-up block of Xi ’an were selected. By field measurement, the cooling effect could be extended one hundred meters from the park boundary, connecting between two parks. Furthermore, the road and greening within the block demonstrate significant influence on the cooling diffusion by regression analysis. Based on ENVI-met simulation, the ratio of the tree and the grass, the layout of the tree and the grass, and the layout of the paving, were analyzed at different proportions of greening and paving of park. Finally, combination of the daytime Physiological Equivalent Temperature (PET) and nighttime air temperature was proposed to choose the optimum layouts: the trees concentrated in the center and the pavement with more roads. Results can provide insights for designing pocket parks based on the thermal environment improvement.

During the process of the high-speed urbanization in Chinese cities, traditional districts renewal is attracting more and more attention. Up to now, the social, economic, political status, and the interaction between each factor have been seriously discussed on urban traditional districts. However, the effects on urban microclimate and the residential living conditions in traditional districts are not well discussed. However, it is strongly related to the living comfort and citizens’ well-being. In this research, two typical traditional districts in Xi’an are selected as case study. According to the original situation of building functions and the community characteristics, two renewal plans are proposed by adding vegetation in open spaces (V), and adding vegetation combined with building redevelopment (V&B), in order to balance the living convenience and thermal environment. Via ENVI-met simulation, the effects of the district renewal plans on thermal environment includes wind speed, air temperature, and mean radiant temperature are evaluated. This study provides method of environmental evaluation for traditional districts renewal, which contributes to sustainable urban planning in historical districts, and provides recommendations for related policy development.