## 2 Materials and Methods
### Methodology  
In this study, the US LEED rating system was employed due to its focus towards energy consumption and for being a widely used system in the local environment. For modeling, Autodesk Revit was selected due to its building information modeling (BIM) compatibility which can not only communicate with energy software, but also structural software such as ETABS and SAP2000. For the energy analysis, Green Building Studio was chosen because of its easy information sharing between various programs. The model was made in Revit and exported to a glyxml file for the energy analysis.  
The US LEED codes for homes and schools were utilized for the house. The US LEED-NC was utilized for the office building design, and the US-LEED Core and Shells was utilized for the warehouse design. These code requirements were incorporated in the software models while keeping in mind the ASHRAE and Energy Code of Pakistan guidelines for comparison purposes. ASHRAE 140 [41] was used for model testing. Both ASHRAE and US LEED provide different codes for different case scenarios but have similar basic approaches to achieve an energy-efficient design. Figure 4 shows the step-by-step methodology adopted in this study. The description of these steps are as follows:  
1. Initially, a three-dimensional model of a room was developed in Revit as per ASHRAE 140 code requirements, and the results generated by Green Building Studio were checked. This step is important before doing the actual modeling, as energy calculations are too extensive to be checked manually.
2. Afterwards, the initial 3D model for the building was prepared in Revit from available information, plans, and sections. For this research, three models were created: a house, an office building, and a warehouse.
3. The building design is modified if required. Building orientation was changed and windows were relocated according to ASHRAE and US LEED guidelines for basic improvements. New energy-efficient materials were applied to the design.  
Figure 3: Different types of roof materials for office and warehouse buildings. (**a**) RO1; (**b**) RO2; (**c**) RO4; (**d**) RO5; (**e**) RW5; (**f**) RW6.  
4. The model was exported to the gbxml format and uploaded to Green Building Studio to check the building performance. This model was further analyzed with the Insight software for building improvements.
5. Based on the results, the building design was further modified inside Revit. If the building modifications were drastic, the structural stability must be checked. Models were counter-checked for stability in ETABS and SAP2000. The Revit model has the capability to export to these software with all information intact.
6. Once all the data was updated, the model was exported to Green Building Studio (GBS) for energy analysis again. Performing analysis on GBS will not only provide results but also suggestions for economizing the structure.
7. Life-cycle cost analysis was performed to check the feasibility of the project and for cost recovery.  
If the building is economical, the final drawings for the project are generated for the client. If the building turns out to be unfavorable, the Revit model is revisited and further modified. After many trials, it may or may not be concluded that cost recovery would be possible. The US LEED certification checklist will then be finalized and the approximate certification level will be discussed.