Abstract
PurposeOptimisation of daylight admission through window is crucial for alleviating glare while maintaining useful daylight levels in order to enhance occupants' health, visual comfort and moderating lighting energy consumption. Amongst various solutions, fixed external shade is an affordable solution for housing spaces that need to be sophisticatedly designed, especially during the period of increasing home spaces as working environments. In the humid subtropical region, daylight control plays an important role in indoor comfort, particularly with areas with a high window to wall ratio (WWR). Due to the insufficient amount of such study on non-office spaces in Australia, shading-related standards are not addressed in Australian building codes.Design/methodology/approachThe chosen methodology for the research is a quantitative data collection and analysis through field measurement and simulation simultaneously. The first step is a multi-objective optimisation of shading elements through a non-dominated sorting genetic algorithm (NSGA-II) on parametric modelling via Rhino3D CAD and simulation engines (DIVA and ClimateStudio). In the second phase, the Pareto front solutions are validated by experimental measurements within a room with a single north-facing window (the most probable for the daytime glare in Sydney) for the seven most common local window configurations.FindingsThrough the simulation of ten genes, 1,560 values and 2.4 × 1,019 of search space, this study found an optimum shade for each local common window layout, resulted in +22% in (UDI) and −16% in views with discomfort glare on average. Moreover, an all-purpose polygonal shade showed an average of 4.6% increase in UDI and a 5.83% decrease in the percentage of views with discomfort glare.Research limitations/implicationsThe findings are subject to the room dimensions, window dimensions and layouts, and orientation of windows for selected residential buildings in Sydney.Originality/valueThe study contributes to the development of highly accurate fixed external shading systems with rectangular and tapered-form external shapes. A real-time measurement by luminance-metre sensors and HQ cameras located at six eye levels is conducted to corroborate simulation results of the visual comfort.
Highlights
Australia is distinguished by the frequent bright and cloudless skies even in winter, whilst European countries experience overcast skies during winter that are deemed critical in terms of daylight illumination and window design (Kittler and Darula, 2019)
This study proves adding suggested external shades reduces sDG by an average of 16% which means discomfort glare probability reduction for Sydney
This study determined the effect of an external shading system on a north-facing window located in Sydney, Australia, aiming to mitigate discomfort glare and maintain daylight provision at the highest possible level
Summary
Australia is distinguished by the frequent bright and cloudless skies even in winter, whilst European countries experience overcast skies during winter that are deemed critical in terms of daylight illumination and window design (Kittler and Darula, 2019). Useful Daylight illuminances (UDI) has a significant role in the maintenance of indoor comfort. The COVID-19 pandemic, which has brought an increase in indoor home spaces as working environments (Hu, 2020; Wuersch and Neher, 2020; Morawska et al, 2020), is growing the importance of the study on residential indoor visual comfort matters, especially regarding the reciprocal relationship between avoiding glare and indoor daylight access. To alleviate the harsh glare, all fenestration subjected to direct sunlight should have to be equipped to handle glare with some sort of sun control (ASHRAE, 2009), which is the paper’s main aim. Efficient use of sunlight illumination convinces us to use shading systems to prevent unsolicited insolation and the connected glare (ASHRAE Design_Guide, 2015)
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