Optimization of Skylights to Provide Lighting and Reduce Energy Consumption in Integrated Store Spaces in Tehran Case Study: Shahrvand Chain Store

Due to demographic changes and the growing trend of urbanization and the consequent increase in energy demand in recent decades, energy supply has become one of the main concerns of human societies. The use of passive solutions and renewable resources for sustainable design, especially in the construction sector, is one of the ways to deal with the consequences of the crisis due to limited fossil fuels and greenhouse gas emissions. Among renewable energy, solar energy plays an important role in meeting the needs of the building, especially lighting. Daylight is one of the basic components of a passive solar building design. Proper integration of daylight with architectural design is considered one of the most effective means of reducing energy and the environmental problems and improve the quality of visual comfort and health. Among the various daylight systems available today, toplighting is used because of its ability to provide uniform daylight in spaces without facades or in deep rooms. The use of skylights in large stores, due to the high energy demand of this type of building and also the potential of using natural light, can reduce energy consumption and introduce daylight to deeper spaces. The purpose of this study is primarily to investigate the thermal and lighting performance of the installation of skylights in store buildings and in particular the Shahrvand Al-Ahmad branch store in Tehran. To achieve this goal, after defining the parameters affecting energy and light performance, the process of simulating daylight and energy was done in two stages: 1) skylight, and 2) clerestory. Models with parameters including the dimensions of the skylight, the height of the north and south curb, the type of glass in the model with skylights, and the height and type of glass in the model with clerestory were simulated, so that an appropriate solution in terms of light and energy can be achieved with the help of multi-objective optimization process,. The objectives are energy use intensity (EUI) and spatial useful daylight illuminance (sUDI), which were evaluated after the optimization process with the help of Pareto front diagrams. Finally, in the two mentioned models, sensitivity analysis was performed to evaluate the effect of the studied variables on the outputs.  According to the results, the skylights with SFR of 4.97% to 6.09% with the lowest curb height and double glazing with 0.10 emission coefficient, and high clerestories on the north and south walls and low clerestories on the east and west walls with double glazing with 0.10 emission coefficient have the best performance in terms of daylight and energy. Also, the skylight provides the same level of daylight with more uniformity compared to the clerestory in the same conditions, with 35% less glass area but with 12 kWh/m2 of higher energy consumption. According to the results of sensitivity analysis, the dimensions of the skylight and the height of the southern clerestory have the greatest impact on daylight and energy use in the model with skylights and clerestories, respectively.