## 3 Material and Method
### Methodology  
It is known that, depending on the location, the amount of household waste collected from buildings has increased by up to 30% including the extra waste generated during the pandemic [9; 12]. Typically, weekly household waste quantities [20; 42] are used to calculate the chute diameter; however, considering these increases and a safety margin, the diameter was set 1.5 times larger. To prevent potential accidents from user contact, the minimum insulation thickness was determined, and the adequacy of the mechanical and chemical properties of AISI 304 stainless steel for system continuity was assessed. Additionally, the load on the system and the volume and quantity of waste containers required for weekly maintenance were evaluated. Based on these considerations, numerical calculation methods were applied in a sample refuse chute model to determine the static suitability of the chute body thickness, the static compliance of the chute support dimensions, chute diameter, chute thickness, fan airflow rate, ventilation duct diameter, minimum rock wool thickness for human contact safety, and the required number of backup containers. To optimize all of these numerical calculations, a code was developed using MATLAB software. Additionally, computational fluid dynamics (CFD) analysis was conducted using Ansys software to understand the airflow dynamics and clarify the flow parameters related to airborne infection transmission on residential floors in buildings equipped with refuse chutes. In this study, the circular economy (CE) model was considered as an essential framework for designing refuse chute systems. The circular economy approach aims to manage waste separation and recycling at the source in an efficient and sustainable manner [13]. Within this framework, refuse chutes are generally designed to facilitate source-based waste collection and promote recycling. Additionally, the newly designed refuse chute  
Figure 11: Thermal insulation. system in this study ensures cleaner, safer, and healthier waste separation. The new refuse chute system also incorporates measures for fire safety and pandemic conditions, aiming to protect the health not only of users, but also of the workers handling the waste, thereby contributing to sustainable waste management. In buildings without an effective refuse chute system, recyclable waste, such as packaging materials, is collected in a mixed manner and sent to waste disposal sites. This approach makes waste separation challenging and costly, and although such waste can go through various technological processes to obtain clean materials, high-quality recycled material is often difficult to achieve [20]. Therefore, the source separation method involves sorting waste at its origin--namely, our homes and workplaces--which is the most crucial step for recycling. The multi-sorter refuse chute systems promoted in this paper facilitate waste separation at the source as much as possible, enhancing efficiency and supporting environmental sustainability goals. Furthermore, updating cleaning systems to mitigate infection spread and installing ventilation systems to counter pathogen movement contribute to more sustainable and uninterrupted waste efficiency. Additionally, a list of all equipment used in the system was compiled as well as the total cost, if this refuse chute was to be installed in the UK, has been communicated to the readers. Additionally, all the details above-mentioned are provided in Table 1 as a comparative analysis based on a literature review [12; 13; 14; 15; 16; 17; 18; 19; 20; 21; 22; 42; 43] to help the readers more easily understand the advantages and disadvantages of the current and renewed design compared to the old version.