Scaled outdoor experimental investigation of thermal environment and surface energy balance in deep and shallow street canyons under various sky conditions

Hang, Jian; Wang, Dongyang; Zeng, Liyue; Ren, L.; Shi, Yurong; Zhang, Xuelin

doi:10.1016/j.buildenv.2022.109618

Cited by 21 publications

(3 citation statements)

References 50 publications

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“…Real-world urban airflow dynamics are influenced by a range of complex atmospheric conditions. Future studies have been planned to explore how varying stability conditions affect the relationship between urban design parameters and C d using either numerical simulations or scaled outdoor measurements [50][51][52][53] that are exposed to varying weather conditions. An observation campaign in the real city is also planned in future work.…”

Section: Limitations and Future Workmentioning

confidence: 99%

Influence of Various Urban Morphological Parameters on Urban Canopy Ventilation: A Parametric Numerical Study

Zeng,

Zhang,

et al. 2024

Atmosphere

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Numerical simulation is vital for evaluating urban ventilation. However, accurate urban-scale ventilation modeling requires extensive building surface simulation for computational demand. The distributed drag force approach simplifies the urban canopy by modeling buildings as a porous volume that accounts for momentum and turbulence. This method is a practical solution for simulating urban airflow. The drag force coefficient (Cd) is a crucial aerodynamic parameter in this approach. This study examines how Cd varies with urban design parameters such as plan area density (λp), average building height (H), frontal area density (λf), floor aspect ratio (AR), and sky view factor (SVF). Employing extensive numerical simulations conducted under neutral atmospheric conditions, we explore ranges of λp = 0.04–0.07 and λf = 0.1–1.2. The numerical model has been validated against existing wind tunnel data. The results show that Cd is insensitive to the model scale and background wind speed. We discover a nonlinear relationship between Cd and the parameters λp, λf, and SVF. For urban layouts with cubic-shaped buildings, Cd peaks at different λp within the range of 0.2~0.8. When λp and H are constant, Cd has a linear relationship with AR and λf. It is recommended to use λp, SVF, and AR as predictors for Cd across various urban configurations.

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Section: Limitations and Future Workmentioning

confidence: 99%

Influence of Various Urban Morphological Parameters on Urban Canopy Ventilation: A Parametric Numerical Study

Zeng,

Zhang,

et al. 2024

Atmosphere

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“…According to the monthly average data of 82 stations in China from 1960 to 1970, the sky temperature at each station and its differences from the air temperature were calculated. The results of T sol model calculations that ignore the effect of sky radiation will be biased in areas with strong sky radiation [12].…”

Section: Correlation Sitementioning

confidence: 99%

Simplified Calculation of Tsol Based on Dynamic Numerical Simulation of Tsky in Diverse Climates in China

2023

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An accurate calculation of sol-air temperature (Tsol) is very important for urban environments and building energy consumption. There are various methods that can be used to calculate Tsol by considering sky radiation effects. Climate conditions are vital factors affecting sky temperature (Tsky). In this paper, in order to select an appropriate calculation method to determine long-wave radiation, a theoretical analysis was carried out based on the effect of Tsky on the thermal gain of building envelopes due to long-wave radiation. Typical annual meteorological data were selected to calculate Tsol for 10 meteorological stations covering five building thermal zones in China. The application of the Tsol model was studied using MBE as the measurement standard, and a linear regression equation for the calorific value of the envelope obtained via the Tsky estimation method and the Tsky dynamic calculation method was established. The results show that relative humidity is the key meteorological factor that affects the application of the Tsol model and that the Tsky dynamic calculation should be used to calculate long-wave radiation in regions with low relative humidity. A thermal correction equation for buildings was obtained for use in areas lacking meteorological data and to provide a basis for sustainable building design.

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“…The influence of urban morphological parameters on the outdoor thermal environment cannot be ignored [38,39]. The architectural layout, height, orientation, density, floor area ratio, height-to-width ratio (H/W), and sky view factor (SVF) are the dominant factors affecting radiative and convective heat exchange in urban spaces [40][41][42]. The H/W is an important parameter describing the openness of streets.…”

Section: Introductionmentioning

confidence: 99%

Evaluating the Effects of Different Improvement Strategies for the Outdoor Thermal Environment at a University Campus in the Summer: A Case Study in Northern China

Liu

2022

Buildings

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A lack of consideration of outdoor spaces of universities has resulted in lower outdoor thermal comfort in summer. This study investigates the thermal comfort of outdoor spaces of a university in summer and proposes the model’s accuracy and optimization strategies to improve the outdoor thermal environment, including vegetation greening, building morphology, and surface albedo. The ENVI-met program was used for the simulation. The measured data were utilized to verify the accuracy of the simulation model. The typical meteorological year data were applied as the inlet boundary condition of the optimized case. The simulation results show that vegetation greening has the most significant effect on improving the outdoor thermal environment. At a greening rate of 45%, the air temperature (Ta), mean radiant temperature (Tmrt), and physiological equivalent temperature (PET) in the study area were 3.2 °C, 14.4 °C, and 6.9 °C lower, respectively, than that in the base case. In areas shaded by building, the Ta, Tmrt, and PET were 2 °C, 8.7 °C, and 5.5 °C lower, respectively, than that in the base case. Increasing the height of buildings did not significantly improve thermal comfort when the height-to-width ratio (H/W) exceeded 1.0. Increasing the ground albedo from 0.2 (base case) to 0.6 can reduce the Ta by 1.44 °C but increase the Tmrt by 3.7 °C and the PET by 4.3 °C. These findings can be used by urban planners to develop sustainable cities and improve thermal comfort on university campuses.

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Scaled outdoor experimental investigation of thermal environment and surface energy balance in deep and shallow street canyons under various sky conditions

Cited by 21 publications

References 50 publications

Influence of Various Urban Morphological Parameters on Urban Canopy Ventilation: A Parametric Numerical Study

Influence of Various Urban Morphological Parameters on Urban Canopy Ventilation: A Parametric Numerical Study

Simplified Calculation of Tsol Based on Dynamic Numerical Simulation of Tsky in Diverse Climates in China

Evaluating the Effects of Different Improvement Strategies for the Outdoor Thermal Environment at a University Campus in the Summer: A Case Study in Northern China

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