Accessing BIM Data

The “Accessing BIM Data” work is based on the Project 1 with parametric model using Revit API in order to pass parameters’ values between the project and the families. The “Accessing BIM Data” work is implemented with the Revit program, the Excel program, and the Visual C# Express 2008 program.

The parametric model is focused on the PV panel which was developed in the Project 1. The parametric modeling method in the Project 1 is replaced with the Revit API method in the Project 2.

A. Procedure for the Accessing BIM Data

The figure 1 shows the work process for the “Accessing BIM Data”.

Figure 1. Diagram of procedure for the accessing BIM data

The procedure which describes in the Figure 1 has four steps:

· Step #1: Calculate the solar PV angle

This step uses the equations from the manual of Solar Collectors and Photovoltaic in energyPRO (2009) in order to calculate the angle of incidence of beam radiation on horizontal . The detail of the equations is described in the Parametric Model for Solar PV in Project 1. The result of the calculation is implemented with the MS Excel program.

The results are available for only College Station, Texas.

· Step #2: Reformat the result with CSV file in the Excel program

This step is for using the results of the solar PV angle in the Visual C# Express 2008. In other words, the dataset of the results for the solar PV angle is made by converting original file type of the Excel file to CSV file type.

· Step #3: Picking up the results with User-Interface Design (UID)

This step is writing source codes in the Visual C# Express 2008 in order to call the results of the solar PV angle. In addition, this step can also develop user interface design (UID). The UID allows users can input parameters to calculate Solar PV angle. The parameters are composed of month, day, and hour.

· Step #4: Applying values into the Revit program

This step is to receive the results by executing the Visual C# Express program and the values are applied and implemented in the Revit program.

B. Source Code in the Visual C# Express program

The Visual C# Express program has two windows. One (Command.cs) is to communicate CSV file and the Revit program. Another (DATE and TIME for PV ANGLE.cs) is for the user interface design (UID) which users can input the parameters for the solar PV.

Figure 2 shows the screenshot for the window of the Visual C# Express program.

Figure 2. Screenshot of the Visual C# Express program

The source code is written to use user interface design, to get results of the PV angle from CSV file, and to transfer the results to the Revit program. The results transferred will affect the angle of the three solar PV panels which are currently installed in the Project 1.

The source code can be found in the Appendix.

C. Implementation of the Source Code

After developing the source code with the Visual C# Express 2008, we need to load “UserDefinedParameterRedadWrite.dll” with using External Tools in Add-Ins of the Revit program. When we are done loading the dll file, we execute the load file by clicking the run button. Then, we can see the pop-up dialog window which is developed for user interface dialog. Figure 3 shows the pop-up dialog window.

Figure 3. Pop-up window for the user interface dialog

We can select desired month, day, and time of the drop-down menus from the combo boxes. At this time, I choose June, 23, and 12, for the month, day, and time, respectively. Then, we can click the OK button. After that, the message box is pop-up to make sure the users inputs are right or not.

Figure 4. Pop-up window to show your selection

After clicking again, another window is pop-up to show the calculated angle of the solar PV panel.

Figure 5. Pop-up window to show the calculated PV angle

Once clicking the OK button again, the calculated PV angle applies to the solar PV panels in the Revit. The executed result in the Revit project is shown in the Figure 6.

Figure 6. Screenshot for the results in the Revit project

Figure 7 is the screenshot to compare the calculated angle in the Revit program with dataset file which is pre-calculated and saved CSV file. The June 23rd is 174th days in a year. The value for 12 o’clock of the day is 7.17 degree from horizontal level for the PV panel. From this comparison, we can see that the command of the source code can rightly import the value from CSV file.

Figure 7. Screenshot for the results of the CSV file

Table 1 shows the result scenarios for the solar PV angle in the Revit program after executing the Revit API program. The following results are implemented on June 23^rd. And, the time of the day is 8, 10, and 12 o’clock.

Table 1. Result for the PV angle in the Revit view