Modelling the overheating risk in an uniform high-rise building design with a consideration of urban context and heatwaves

Abstract

Overheating in buildings is one of the increasing concerns related to climate change and can lead to an increase in heat-related health issues and higher energy consumption due to the use of air conditioning systems. Literature shows that internal conditions and demand on environmental control systems can vary with height within buildings. However, an architectural trend towards highly glazed façades for tall buildings suggests the vertical gradient of performance is not always considered in the design process. By simulating a high-rise residential building in London, a comparative analysis of the overheating risks and daylighting at different levels in the building was conducted. In this study the model was able to consider the influence of surrounding built environment on solar gain and so influence of urban location on overheating risk was taken into account. Simulations were conducted using typical reference years as well as meteorological data for specific heat-wave periods experienced in London and that are expected to become more intense and frequent due to climate change. Passive mitigation options (external shading) are demonstrated to help reduce overheating occurrence by 74%, at the same time the impact of decreased daylighting (30%) is less problematic at higher levels where daylight factor is greater.

Impacts of Urban Form on Thermal Environment Near the Surface Region at Pedestrian Height: A Case Study Based on High-Density Built-Up Areas of Nanjing City in China

“…Hence, the thermal-affected environment problem in cities is an important issue, which is mainly related to urban climate change and sustainable development. High density is considered to be an inevitable trend in urban construction and plays an important role in improving the quality of human life, promoting the healthy development of cities [9], improving urban traffic, and reducing energy consumption [10]. However, high density also aggravates the urban heat island effect and poses a threat to human health.…”

“…The variation of building height affects the sunshine and shadows inside street blocks, changing the urban near surface temperature [22]; an extremely high building density slows down the near surface airflows, causing poor ventilation [19]. Consequently, not only air circulation and pollutant dispersion, especially in the near surface region [10,18] are obstructed [23], but also the urban climate and heat island effect are affected [24,25], which eventually leads to the loss of self-regulation ability of an urban ecosystem.…”

Advances Toward a Net-Zero Global Building Sector

“…For instance, reports (228,229) indicate that project teams in heating-dominated climates can overlook the importance of designing to ensure summer comfort in addition to winter comfort, resulting in overheating in the summer. With a changing climate, however, it is imperative to design for the anticipated future climate in a region (230). For example, although active cooling may not be required at the time of construction, future-proof building design should incorporate ample shading elements and consider future installation of mechanical cooling.…”

Overheating in residential buildings: Challenges and opportunities

“…Commonly, weather data for a year with a hot summer or with heat wave periods were used. 15,21 Some also used typical meteorological year weather files. 16,22 In the UK, CIBSE TM52 and CIBSE TM59 require the use of the local design summer year (DSY) weather file, which is the year with the third highest average dry-bulb temperature from April to September during a 20-year period.…”

“…For residential building designs, assessment of overheating is commonly based on building simulations as specified in CIBSE TM52 and CIBSE TM59. 15,16,21,22 One uncertainty in the assessment of overheating is occupant behavioural assumptions in residential buildings which can have significant impact on building thermal and energy efficiency performance. The complexities in the occupant behaviour assumptions such as occupancy profile, window/door and curtain/blinds shading operations, appliances operation, etc.…”