## 1 Introduction  
The energy consumption of sports buildings is a critical aspect of their design and operation, as it significantly impacts both their environmental footprint and operational costs [1]. Efficient energy use in these structures is essential to reduce greenhouse gas emissions and promote sustainability in the sports sector [2]. Integrating renewable energy sources and advanced energy-management systems can greatly enhance the energy efficiency of sports facilities [3]. Additionally, careful consideration of insulation, lighting, and HVAC systems during the design phase can lead to substantial long-term savings and improved environmental performance [4]. These structures often require significant energy inputs due to their large spaces, high ceilings, and the need for specialized climate control systems [5]. The energy demand is influenced by factors such as lighting, heating, ventilation, air conditioning (HVAC), and hot water for showers and swimming pools [6]. To enhance energy efficiency in sports buildings, various energy-saving measures can be implemented. These include installing energy-efficient lighting systems, such as LED fixtures, which consume less electricity and have a longer lifespan [7]. Additionally, optimizing the HVAC system with energy-efficient equipment and smart controls can significantly reduce energy consumption as well as building energy management systems [8]. The use of renewable energy sources, such as solar panels or geothermal systems, can further contribute to sustainability [9; 10]. Comfort conditions are another essential consideration in sports buildings. Thermal comfort is subjective, varying from person to person based on factors like preferences, clothing, and activity level. Environmental conditions such as temperature and humidity also play a significant role in individual perceptions of comfort [11]. These facilities must maintain appropriate temperature, humidity, and air quality to ensure a comfortable environment for athletes and spectators [12]. This can be achieved by incorporating advanced climate control systems or proper insulation to prevent heat loss or gain, which are considered passive design strategies. Additionally, natural ventilation and daylighting can enhance comfort while reducing energy use [13]. By adopting sustainable practices and technologies, these buildings can achieve energy efficiency while maintaining a pleasant environment for all users [14]. Most sports facilities in Serbia were built between 1960 and 1980, and many sports centers in Belgrade share similar characteristics. These centers generally feature a main sports hall and additional areas designed to support its operations. The main sports hall is typically multifunctional and used for various indoor team sports such as basketball, volleyball, or handball. Sports centers are organized into distinct spaces, primarily designated for public use, players, management, and technical equipment [15]. Energy consumption in sports buildings is influenced by several key factors, including location, size, and the materials used in their construction [16]. The energy demand in these facilities encompasses both thermal energy for heating and electrical energy for operating equipment, air conditioning, ventilation, and lighting systems [17; 18; 19; 20]. The local climate is a major determinant of energy consumption levels, with sports buildings in Mediterranean climates typically requiring around 260 kWh/m\({}^{2}\), while those in continental climates may consume up to 490 kWh/m\({}^{2}\) due to harsher weather conditions [21; 22]. The comfort requirements for different user groups, such as the public and players, as well as the variety of services provided within the facility, significantly impact energy use. Ensuring the right comfort levels often involves balancing the needs of spectators and athletes, which can lead to increased energy consumption.