Evaluation Schoolyard Wind Comfort Changes Due to Rapid Developments: Case Study of Nanjing, China

Qiuxia Xu,Zhen Xu,Chayn Sun

doi:10.3390/atmos13010043

Abstract

(1) Background: Evaluation of wind environments regarding pedestrian comfort may unveil potential hotspot areas, particularly in the context of the rapid urban development in China since the 1990s. (2) Method: With primary schools in Nanjing as case studies, the authors simulated the wind environment of schoolyards with the computational fluid dynamics (CFD) approach and evaluated relevant wind comfort criteria. (3) Results: The study showed that the comfortable wind environment of schoolyards generally expanded in three primary schools in summer and winter, and wind speed and the comfortable wind level decreased in some outdoor schoolyard spaces. The results also indicate that the mean wind speed of the schoolyards did not linearly correlate to the building density either within or outside the schools. An increase in the building height of the primary schools could improve the wind comfort of the schoolyard, but the increased building height in the vicinity may worsen the wind comfort in the schools. Meanwhile, a lift-up or step-shaped building design for schools can improve wind comfort in schoolyards. (4) Conclusions: This study provided simulated results and an approach for urban designers to evaluate and improve the wind environment for school children’s outdoor activities.

Highlights

Pedestrian wind environment, induced by substantial urban development, has become a major concern in high-density cities in recent decades [1]
(3) Results: The study showed that the comfortable wind environment of schoolyards generally expanded in three primary schools in summer and winter, and wind speed and the comfortable wind level decreased in some outdoor schoolyard spaces
In the northern mid-latitudes, the data of 822 worldwide surface weather stations has shown that surface wind speeds have declined by 5–15% from 1979–2008 and the 25–60% reduction in wind speed stems from the increased surface roughness [3]

Summary

Introduction

Pedestrian wind environment, induced by substantial urban development, has become a major concern in high-density cities in recent decades [1]. One notable wind environment issue involves wind weakening at the pedestrian level, due to overly dense urban planning. This problem has been observed in many regions of the world, and it becomes especially serious in densely built cities at low or mid-latitudes, such as Nanjing, Hongkong, and Tokyo [2]. The construction of skyline structures and high-rise buildings has introduced high-wind velocities around high-rise buildings at the pedestrian level, which could be uncomfortable or even dangerous to pedestrians [8] Compared with adults, these related problems are more serious for children, due to their vulnerable immune systems and weak heat dissipation [9,10]. To improve wind environment comfort, investigating long-term information on wind environment and the effect of morphological wind changes has become a pressing issue for urban design, especially in regard to schoolyards

Objectives

Methods

Results