The influence of urban microclimate vertical variations on the building performance of a high-rise office building at different floors

Abstract

This paper explores the urban microclimate effects on the building performance of high-rise office buildings of different heights. In general, the environment section of buildings’ performance calculation relies on weather station data located in rural areas which are quite different from the actual urban microclimate. How the accuracy of urban microclimate modelling affects the building performance simulation is not understood. We have previously explored horizontal elements’ effects on high-rise office building performance. In this research, wind and temperature vertical variations’ effects on performance at different heights is explored. Compared with the wind in rural areas, the urban wind has more barriers and is more turbulent. The temperature profile in urban areas is also different from that in rural areas because of Urban Heat Island effects. How do these features of urban microclimate influence the performance? Is the influence significant enough and worth modelling? From this research, vertical temperature gradients are a more significant influence on energy use than vertical variation of wind speed and urban boundary layer depth. If the building is extremely high the accurate modelling of wind speed profile may matter as well because the influence of vertical variations on natural ventilation increases with height.

What we know and do not know about New Zealand’s urban microclimate: A critical review

“…The urban microclimate is one of the most critical factors affecting outdoor thermal comfort [33], the urban life quality [9][17] [24], the utilisation of the outdoor public spaces [33] [35] [36], and the liveability and sustainability of cities [14], [8], [37]. There are several thermal comfort indices developed, considering the relationship between microclimate and thermal sensation.…”

“…Jing et al [81], [82], [16] demonstrated that, when modelling the thermal performance of naturally ventilated buildings in dense urban areas, the model must account for: the effect of UHI within the urban canopy layer; the influence of the vertical structure of the wind within the urban boundary layer;…”

“…and thermal balance in a city area [7], [8], [9]. The imbalance of natural airflow and temperature in urban areas has negative impacts on urban microclimate, altering wind flow patterns, exacerbating the urban heat island (UHI), and significantly affecting outdoor thermal comfort [3]- [5], [10].…”

A Simulation-Based Study on the Impact of Parametric Design on Outdoor Thermal Comfort and Urban Overheating

“…One of the causative factors is that the built-up areas are covered by building materials with higher heat absorption than the suburban or rural areas with a higher ratio of vegetation coverage or of water bodies [2,3]. Another factor that causes the UHI effect is the urban geometry formed by high-rise buildings that alter the air dynamics in between street canyons, which potentially prevents cool prevailing winds from entering the core of the city and limits natural ventilation for cooling [4]. Many studies have mentioned the potential risks that urban heat poses to human health and well-being, which can be fatal under extremely hot weather events [5,6].…”