Comparison of energy consumption and life cycle assessment in a building equipped with smart windows (electrochromic, thermochromic and photochromic): Case study in Tehran

• The consumption of cooling and heating energy and the total power consumption in the building is directly related to the technology used in smart windows. • Smart window technology aims to reduce energy consumption and provide comfortable temperature in the majority of heating and cooling and efficient lighting. • Photochromic and electrochromic have higher efficiency than thermochromic windows. • The life cycle assessment has shown that the most environmental effects are related to lightweight concrete in the modeled building and the metals used in the building. In contemporary society, advanced technologies play a crucial role in enhancing quality of life and promoting energy efficiency. A notable example is the implementation of smart windows. These include electrochromic, thermochromic, and photochromic windows. These windows can regulate the transmission of light and heat. They adjust based on environmental conditions and user requirements. Such capabilities help reduce energy consumption significantly. At the same time, they improve comfort levels in both residential and commercial environments. This study focuses on reducing energy consumption and building loads. These loads include heating, cooling, and total power consumption, which also covers lighting. Four types of windows were evaluated. These are: conventional double-glazed windows with air, thermochromic smart windows, electrochromic smart windows, and photochromic smart windows. The opacity variations of the smart windows respond to sunlight intensity. These responses were tailored to the climatic conditions of Tehran. The research was conducted using Design Builder software. Calculations were reported on both an hourly and annual basis. The results indicated that considering the U-value and Tehran’s climatic conditions, along with a comfort temperature of 22 degrees Celsius, the best energy savings are observed in buildings with photochromic smart windows. These are followed by electrochromic, thermochromic smart windows, and double-glazed windows. The percentage changes in energy consumption and total power for each type of window, relative to the baseline scenario, are as follows: thermochromic windows show a 2 % improvement, electrochromic windows an 8.2 % improvement, and photochromic windows an 11.7 % improvement.