Comparison of daylight simulation methods for reflected sunlight from curtain walls
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Comparison of daylight simulation methods for reflected sunlight from curtain walls
1. Department of Building Services Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China 2. Wenzhou University, Wenzhou City, Zhejiang Province, China
Abstract
Keywords
Curtain walls are more and more commonly used as building facades. They allow a better daylight
daylighting,
availability and a direct connection to exterior environments. Meanwhile, due to the high specular
reflected sunlight,
reflections, they may also introduce negative impacts, such as glare and urban heat island effects,
daylight simulation,
to the surround, especially in dense and urban environments. Therefore, it is important to
ray-tracing
effectively characterize the reflected sunlight from curtain walls. This study aimed to compare how different simulation methods can be used to characterize the reflected sunlight from curtain walls. It was found that the modeling of the sun and sky, ambient calculation, and the modeling of the building façade significantly affected the simulation results. A combination of forward and
Research Article
Jun Wang1, Minchen Wei1 (), Xiukai Ruan2 ()
Article History Received: 15 February 2020 Revised: 20 July 2020 Accepted: 24 July 2020
backward ray-tracing is recommended, with forward ray-tracing for identifying the curtain wall areas reflecting sunlight and backward ray-tracing for calculating illuminance due to reflected
© Tsinghua University Press and
sunlight. A follow-up work is planned to investigate how different parameters will affect the
Springer-Verlag GmbH Germany,
simulation results and which method can produce similar results as field measurements.
part of Springer Nature 2020
1 1.1
Introduction The effects of reflected sunlight from curtain walls
E-mail: [email protected] (Minchen Wei); [email protected] (Xiukai Ruan)
Building Thermal, Lighting, and Acoustics Modeling
Curtain walls are becoming more and more popular in high-rise buildings, as they not only present the building aesthetics and modernity, but also provide better daylight availability and interaction between interior and exterior environments (Galasiu et al. 2015; Aksamija 2016). Though curtain walls use different types of glass or coatings for different purposes, such as reducing surface temperature and solar heat gains of buildings, most of them have high reflectance and some have high specularities (Chow et al. 2010; DiLaura et al. 2011; Gobakis et al. 2015). These curtain walls reflect sunlight and introduce negative impacts, such as glare, severe thermal radiation, and urban heat island (Suk 2007; Chow et al. 2010; Yuan et al. 2015; Danks et al. 2016; Suk et al. 2017; Ichinose et al. 2017), to the surrounding buildings, pedestrians, and drivers. For example, the concave shape of the curtain walls of Vdara Hotel in Las Vegas and
Walkie Talkie Building in London caused burns on people and fires on a car due to the concentration of the reflected sunlight (Walker 2013; Garfield 2
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