## 3 Methodology  
In Hong Kong, high rise public rental housing accommodates 44.8% of the population [24; 31]. These public housings generally share a similar building layout model called concord type. The concord type includes one core structure and four wings extending in four directions. The core structure part generally hosts building service functions such as duct wells and lifts. Therefore, the core part is usually unconditioned. The wings connect to the core and are the main occupancy area. Concord-type buildings present the advantages of a better building thermal performance and less hours of discomfort [33]. The concord-type layout is a common starting point for passive design analysis in Hong Kong. The concord-type public residential buildings generally present higher building information availability and homogeneous characteristics in building design and room conditioning setups, which makes them satisfactory cases for building performance study. As a baseline for comparison, the energy use for public housing is 528 MJ/m\({}^{2}\)/annum [32]. This study employs the whole building simulation to reveal the predicted building performance throughout a year with local predicting climate data. Building information including geometry and material is inputted in the energy simulation software to generate the performance data for a detailed analysis. The data can reveal performance differences in different scales including annual energy-saving data, detailed hourly energy use and comfort, and even detailed surface temperature. EnergyPlus v8.8.0 is adopted for whole building simulation. EnergyPlus is an energy simulation software developed by the National Renewable Energy Laboratory (NREL) of the United States. It is widely used in research to study building energy use and occupancy comfort. The data analysis will focus on the annual consumption reduction and the saving characteristics of different hours of the day. Input values from research, design standards, and local practices are used for building modeling. This study sets variables for passive cooling techniques to discrete values for comparison based on the recommended range, and employs the local benchmarks on residential buildings to compare energy efficiency. The basic model building layout is shown in Figure 1, which shows the typical floor layout and conditioned zone of high-rise public housing in Hong Kong. The original building has eight flats per floor with 40 floors. Each flat is about 45 m\({}^{2}\). Each floor is 2.75 m in height. From the study of [PERSON] et al. (2018), the concord type has a better thermal performance than other types of public housing layout. The windows follow the construction layout. The windows are 1.2 m in height and are situated 0.8 m above the floor. Originally, the windows of conditioned zones have overhangs directly above the windows with an OPF at 0.3. The fixed condition for simulation is refers to research and the Chartered Institution of Building Services Engineers (CIBSE)-recommended value. The occupancy density is 0.08 people/m\({}^{2}\) assuming 3-4 people per flat. The internal heat source from occupants is 100 W per person. The lighting load density and equipment load density is 15 W/m\({}^{2}\). The cooling setpoint is assumed at 25 \({}^{\circ}\)C as the balanced value for common settings in Hong Kong. The conditioned area will have the same air conditioning operation schedule as in Figure 2. The construction and building materials are modeled based on common practice and real building data. Table 1 presents the typical building construction in public residential housing in Hong Kong and summarizes the U-value of building material data in detail. The U-values of the materials refer to [PERSON] et al. (2018). Tables 2 and 3 illustrate the material properties of glazing and PCM, respectively. The data in this study refer to [PERSON] et al. (2018) and PLUSS (2018). Especially, the enthalpy-temperature characteristics of the SavE phase change material are extracted from its technical data sheet (2018).