Today, sustainable development has become the goal of many countries in the world due to the limitation of energy resources and planning to reduce consumption and dependence on it in various sectors. And about thirty percent of the world's total energy consumption is consumed in the building sector (Kaasalainen, Mäkinen, Lehtinen, Moisio, & Vinha, 2020). In a study conducted on an office building as an example, it shows that lighting, cooling and heating are the main energy-consuming parts in a building, so these three parts are considered the main parts to optimize energy consumption in buildings (Fasi & Budaiwi, 2015). Of course, it should be noted that with the increasing progress of technologies related to the construction industry in the last decade and the use of proper insulation in buildings, the energy consumption for heating and cooling loads in buildings has decreased compared to the past. But in the meantime, the energy consumption for lighting has increased so that its amount is not only insignificant, but also comparable to the energy consumption in the cooling and heating sector (Bokel, 2007). According to estimates, about 25 to 40 percent of the total electrical energy consumed in a building is consumed in the lighting sector (Ihm, Nemri, & Krarti, 2009). For this reason, the planned use of natural daylight in buildings can be a cost-effective strategy to reduce energy consumption. This reduction in consumption occurs mainly by reducing the use of electrical energy to provide lighting. One of the ways to reduce the consumption of electrical energy in the lighting sector is to use more daylight, to maximize the access and use of daylight in indoor environments, special and more attention should be paid to the design of spaces and the surface of windows in the space (Pellegrino, Cammarano).



Considering the undeniable role of the building sector on the total amount of energy consumed in the world and also considering the significant role that the lighting sector has on the total energy consumed in office buildings, it is necessary to design the buildings in such a way as to meet various needs, including The need for lighting to be provided in harmony and to the extent that is needed. The physical and mental health of employees and people using the space will also reduce energy consumption. Therefore, it is necessary to answer this important issue by determining the ratio of the window area to the floor surface, the optimal position, shape and ratio of the window as the main factor of light distribution in the interior space. The present study has been carried out in a descriptive and analytical way in order to optimally use daylight and save energy in the design builder environment. The steps of the research are as follows: first, according to studies and theoretical foundations, concepts related to daylight and energy consumption are examined, and independent variables (shape, position, and the ratio of the opening surface to the surface of the space floor) and dependent variables ( visual comfort and the amount of energy consumption) were determined, and considering that office spaces have a variety of shapes and dimensions, from the main residence space according to the topic of four national regulations, as a reference model for drawing scenarios in Design Builder software. Climate design makes buildings have better comfort conditions and instead of putting a lot of pressure on the heating and cooling systems, the building itself can be effective in providing comfort conditions (passive system) (Shams, 2010). It can cause optimal performance in lighting parameters and save energy consumption, so that the data shows that the component of the ratio of the window area to the floor area, the position of the window and finally the ratio of the dimensions and shape of the opening. By comparing the present study with other studies such as the article that found that the ratio of 20% to 40% is an acceptable range for the area of the window in relation to the surface of the facade. And if the area of the window is more than 50% compared to the facade, although it has a small effect in reducing the consumption load in the lighting sector, it has a significant effect in increasing the cooling load.



(Bokel, 2007) These results can also be seen in this research in such a way that increasing the ratio of the window area to the floor surface, although it causes a small decrease in the reduction of energy consumption in the lighting and heating sector, but it has a significant effect in increasing the cooling load and the total It will consume energy. Or in another article that was conducted with the aim of the effect of the position and dimensions of the window on energy consumption, it was found that horizontal openings have a greater effect on energy conservation than other forms, and openings in a higher position compared to the center position create better daylight atomy. In general, the results of the analyzes show that among the 91 scenarios in the south facade, only two openings (rectangular with a ratio of 1. 5 and WFR 40%) and (rectangular with a ratio of 1. 2 and WFR 50%) can be considered in terms of visual comfort parameters. , receive favorable daylight, but according to the results of the annual fuel consumption study, it can be said that due to the lower total energy consumption, the scenario (rectangular shape with a ratio of 1. 5 and WFR 40%) can be the most efficient option in the south facade of the buildings. It is also recommended to design suitable shades in south-facing windows to achieve more balanced daylight.