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1. Introduction
Optimizing façade configurations to utilize natural energy sources and reduce a building's energy consumption is an important factor in sustainable design. However, due to the variety of architectural concepts and climates, there is no specific standard to determine an optimum window for each design. Scientists are therefore investigating options and methods (Chiesa et al., 2019) to determine the most appropriate window-to-wall ratio (WWR) for buildings with various functions and different climate conditions.
1.1 WWR range
The impact of the window area on a building's daylight and thermal performance has been under investigation for a long time (Reinhart and Walken Horst, 2001). Methods of analysis were first introduced in 1975 in Texas: the sky luminance algorithm and the WWR parameter in total energy demand, which determined a 50% saving in energy consumption (Francisco, 1977). More recently, the impact of WWR and heating, ventilation, and air conditioning (HVAC) systems (Jose and Pablo, 2009) on total energy demand has been presented in climates where heating and/or cooling (Goia et al., 2013) and glare probability (Konstantzos, 2015) are necessary. This parameter has also been investigated in different building functions, such as apartment buildings (Vivian et al., 2020), hotels (Wang et al., 2019) and educational buildings (Alwetaishi and Taki, 2020). However, these studies did not cover the effect of solar radiation on lighting energy consumption with visual comfort. Other studies have considered effects such as window size on ventilation (Ochoa et al., 2012), visual comfort (Cheong et al., 2020), the effect of smart-window systems on reducing energy consumption (Zakirullin, 2020), building materials on lighting and thermal energy consumption (Chinazzo et al., 2019) and shading devices on thermal and lighting energy consumption in office buildings (Suk, 2016; Xue et al., 2019). The impact of WWR on U value and temperature amplitude is also investigated by Ma et al. (2015).
WWR amount study in different climates of Australia determined 10% as the optimal window size, considering the sum of values for cooling and lighting energy consumption as a function of WWR (0–10–20–40%) in all climates (Peter Lyons and Associates, 2008). Goia in 2016 integrated thermal and lighting simulations to find the optimal WWR in all orientations and four different climates in 35–60...