## 7 Discussion  
In the context of sports buildings, passive energy-saving measures focus on design and material strategies that reduce energy consumption without relying solely on active systems [63]. The basic measures include enhancing the thermal insulation of the building envelope that can significantly reduce heat loss and gain, leading to lower heating and cooling energy requirements [48]. In the analysis and execution of energy simulations, various technologies have been considered [64]. However, the primary focus has been on passive measures and improvement in the thermal envelope of some parts of the building. These measures are emphasized due to their potential for significant impact on achieving comfortable indoor conditions while optimizing energy use [65]. Specifically, passive strategies, such as improvement in the thermal envelope of the whole sports center or only one part, give answers to the defined research question:  
RQ1: Is it feasible to implement energy-retrofitting strategies specifically for the sports center, excluding the sports hall, to achieve a significant reduction in overall energy consumption to upgrade the energy class of the building by one level? In Scenario 1, the focus is on improving the energy efficiency of the building's office spaces while deliberately excluding the main sports hall from retrofitting measures. This scenario provides insights into how targeted retrofitting interventions in non-sports hall areas can impact both comfort and energy savings. The retrofitting measures applied to the office spaces resulted in a 15.8% improvement in overall comfort. This enhancement is indicative of the positive effects of energy-efficient upgrades, such as improved insulation, better window glazing, and optimized HVAC systems, on indoor comfort levels. Enhanced comfort can be attributed to reduced thermal fluctuations, improved air quality, and more stable indoor temperatures, which collectively contribute to a more pleasant working environment [66]. Despite the overall comfort improvement, there is a noted decrease in the percentage of comfortable hours during the occupancy period in the office spaces. This reduction suggests that while retrofitting measures improve overall comfort, there might be specific instances or conditions where the comfort levels are less optimal [67]. The estimated energy savings for space heating amount to 51.6%. This significant reduction in energy consumption highlights the effectiveness of the retrofitting measures in improving energy efficiency and upgrading facility energy class for two levels, from E to C.  
Scenario 1 demonstrates that targeted energy retrofitting in office spaces can lead to substantial energy savings and improved overall comfort. However, it also reveals  
Figure 12: Comparison analysis for Scenarios 1, 2, and 3: (**a**) comfort index for the selected office; (**b**) comfort index for universal sports hall. the potential for decreased comfort during specific occupancy periods, emphasizing the need for a holistic approach to retrofitting that balances energy efficiency with occupant comfort. Further investigation into specific comfort issues and the implementation of advanced control systems may enhance the effectiveness of energy-retrofitting measures while maintaining or improving occupant satisfaction [68]. RQ2: Can energy-retrofitting strategies be effectively implemented in a sports hall within a sports center without extending these measures to the entire building, thereby achieving a significant reduction in energy consumption while maintaining or enhancing occupant comfort and operational performance? In Scenario 2, the focus is on retrofitting the thermal envelope of the main sports hall, which involves enhancing insulation, upgrading windows, and improving overall building envelope performance. This scenario aims to evaluate the effects of these improvements on energy consumption and occupant comfort within the sports hall [69].