## 3 Results and Discussion
Contrastingly, significant changes in terms of lighting energy only occurred between the 0% and 20% scenarios, but then stayed largely constant for the remainder of the scenarios. In general, the building gains heat through lights and solar radiation penetrating into the building through the glass, and the building lose some of the heat through the glass by conduction heat losses, as illustrated in Figure 7.  
The total annual heat gained and lost by the windows is summarized in Figure 8; the red and green bars denote the yearly heat gain from windows and lighting, respectively, whereas yearly heat loss via windows is depicted by the blue bars. Figure 8: Annual heat gain vs. annual heat loss (kWh) for different WWR. Figure 7: Lights, solar heat gain, and heat losses caused by the window glass. When transitioning between the 0% and 100% scenarios, the yearly heat gain from windows exhibited a linear increase, while there was a decrease in the yearly sensible heat gain from light. Nonetheless, the variation in diminishment in the energy from light began to be insignificant between the 20% and 100% scenarios. Contrastingly, a linear increase in the yearly heat loss via windows occurred as the window-to-wall ratio increased. Because the rise in heat loss is not the same as the rise in heat gain, it is necessary to achieve a balance between light and solar heat gain to completely exploit energy from solar sources with no reverse impacts. Energy simulation software was used to precisely determine the WWR for the residential structure in the design stage, between 25% and 30%, because altering an individual building element can affect different associated elements. Exploiting daylight using windows assists with partially offsetting the demand for electric lighting and lowers the overall consumption of energy by the building. This can be achieved through the utilization of glazed materials to allow daylight to enter, as well as systems for controlling lighting that are capable of dynamically responding to the level of light. Nevertheless, if passive daylighting approaches are not implemented correctly, this can cause the energy consumption to increase. A factor that accompanies sunlight is solar heat radiation, which can cause a space's HVAC load to increase and reduces the energy savings generated from daylighting. Thus, it is necessary to achieve a balance between solar heat and light gain to effectively exploit solar energy with no reverse impacts. About this balance, because of technological developments achieved in lighting, it is questionable whether natural light is effective in lowering the overall energy consumed by buildings. As a result of the increased energy efficiency of LED luminaires, the energy consumption from light is relatively low, even in situations where the lighting system is functioning at peak capacity. Thus, it is not clear whether the solar energy entering via glazed materials is advantageous or disadvantageous for the overall consumption of energy in buildings. This study proposes that the typical WWR for residential buildings containing a LED lighting system could be lowered to the range of 25-30%, which is lower than the maximum WWR of 40% stipulated in the ASHRAE standard [35]. Furthermore, this study recommends that energy simulation programs should be utilized in the design stage to identify the optimum WWR, between 25% and 30%, for the design of residential structures in the future, because alterations to a single building element can affect a number of associated elements. Even though the optimum WWR can vary between 25% and 30%, it is still an effective representation of the reduction that can be achieved by making the lighting system more efficient.