## 5 Methodology
** The choice of the Turgo turbine was based on its specific suitability for the given flow rate and head conditions. Turgo turbines are well-suited for moderate- to high-head applications with relatively low flow rates, which aligns with the parameters of this study. Fixed Pitch Propeller and Crossflow turbines, on the other hand, might be less effective for the specific conditions of the multi-level carpark setup. 2. **Efficiency and Performance. ** We found that the Turgo turbine offered superior efficiency and power output compared to Fixed Pitch Propeller and Crossflow turbines for our study's parameters. Turgo turbines are known for their high efficiency in converting water's kinetic energy into mechanical energy, particularly in the flow conditions described. 3. **Design Constraints and Practicality. ** Our proposed work's design constraints, such as the floor load capacity and spatial limitations within the carpark, could have influenced the choice of turbine. Turgo turbines might have been more practical and feasible within these constraints compared to the other turbine types. For Fixed Pitch Propeller Turbines, they typically offer high efficiency at constant flow rates but may not perform as well under varying flow conditions. Their efficiency is often optimized for specific flow rates, and they may not be as adaptable to the variable conditions that could be encountered in a multi-level carpark setup. However, Crossflow  
Figure 12: MLCP 2022 monthly rainfall chart. turbines are known for their ability to handle a wide range of flow rates and their relatively simple design. However, they usually have lower efficiency compared to other turbine types like the Turgo turbine, particularly in high-head applications. Their efficiency is often lower because they operate over a broader range of flow rates, which can impact on their overall performance in specific conditions. In summary, we preferred the Turgo turbine due to its alignment with this study's specific conditions and requirements, as well as its efficiency in those conditions. Fixed Pitch Propeller and Crossflow turbines might have been considered less suitable based on their performance characteristics and the design constraints of the PHES system. Water Storage CapacityThe maximum water storage capacity on the top level of an MLCP is considered to ascertain the feasibility of the design. To maximize the water storage, the capacity of the tank will occupy the top floor of the multi-level carpark. The carpark space used as reference in the current proposed work is Block 273 Jurong West Avenue 3, as shown in Figures 13-15. The total surface area of this MLCP is 3311 m\({}^{3}\). The top-level water storage tank occupies the entire level of the MLCP. Using the floor loading capacity, as shown in Table 1, the height of the water tank is determined to be 0.5 m, and due to the turbine being installed at the top of the first level, the head of water will be 12 m. The calculation for the capacity of the lower-level water storage involves dividing the total volume by the height of the level, which is 3 m, and the width of the building is 32.84 m. The storage tank's length is determined to be 16.8 m.