ARCH653 Final Project: Kyungki Kim

BIM and API application: LEED Platinum Grocery Store

Introduction

Through previous works on creating parametric models using basic tools of REVIT Architecture, the class witnessed that there are several drawbacks that makes creating a parametric family complicated. Therefore, it was suggested that we use BIM API (Building Information Modeling Application Programming Interface) in order to support effective model creation. In this blog, a description on how an API program receives information from relevant project and an Microsoft Excel file, and then uses the data to modify parametric family model to meet the needs of the project. Photovoltaic Car Shading Canopy (PV CSC) placed on the parking building has different tilt angles according to the region.

Objective

The objective of this work are to:

• Create an API program that receives data on tilt angles
• Support API with an MS Excel database to determine a new tilt angle
• Send the new tilt angle value to the PV CSC parametric model in the project

Process

As shown in the figure below, data flows from MS Excel Database to REVIT API, and toward the PV CSC parametric family model.

Figure 1. Data flow of API program

General framework of API programming process was adopted from 'CreatingParametricFamilies' examples provided as class material, and it was modified to better fit current project.

1. Initialize model documents
2. Assigning variables
3. Get user input from a pop-up dialog window

Figure 2. Pop-up dialog (comboBox)

     4. Find matching data from Excel database

Table 1. Assumed optimal tilt angles of three US states

In an attempt to simply API programming, mathematical calculations were performed in MS Excel instead of C#. In this table, values in Row2 are optimal tilt angles, Row3 was added to convert the angles to work on already created parametric family models.

     5. Get parameters
     6. Set parameters for existing PV CSC family


 Result

An API program was created and loaded to add-in menu of REVIT Architecture. As Figure3 below shows, the program successfully changes the tilt angles of the PV CSC as different states were selected from the combo-box.

 Figure 3. Pop-up dialog appearing after running API

 Figure 4. PV CSC for Texas

 Figure 5. PV CSC for New York

 Advantages and disadvantages

 According to the work, advantages from using API programming are:

• It becomes possible to access several instances having the same charateristics and make changes to each of them.
• Using MS Excel database instead of putting formula into REVIT interface makes it much easier to have more organized data prepared and send them to the model when it is necessary.
• Usability of large amount of data makes the modeling more realistic considering various factors that may affect the building or parametric family.
• Parametric model becomes more adaptable to projects of different settings.

Disadvantages are:

•  To be able to use BIM API, a certain level of skill in programming is necessary. This necessity forces engineers participating in building modeling using BIM to be used to knowledge in design and computer programming at the same time.
• Programs used for C# programming have different data paths that may cause confusion for those using different programs.

Additional Works and Images

Additional works performed in order to understand more diverse areas of Building Information Modeling application are:

• 4D Construction Animation
• Web-BIM-Database

 The figures below demonstrate grocery store building model created using REVIT Architecture, parametric family modeling, and Web-BIM-Database application images.

Figure 6. Grocery store view

 Figure 7. PV CSC parametric model1

 Figure 8. PV CSC parametric model2

 Figure 9. Web-BIM-Database 1

 Figure 10. Web-BIM-Database 2

 Figure 11. Web-BIM-Database 3

Building Information Model Design

Project description

The design relevant to this BIM modeling is a grocery store construction project that consists of two story-grocery store and three story-parking building. Since the owner of this project seeks to achieve LEED Platinum award, several sustainable features are included in its schematic design. The features include Photovoltaic Car Shading Canopy (PV CSC), Wind Turbine, Green Rooftop System, etc. As shown in figure 1 below, schematic design of the grocery store is completed using REVIT Architecture.

Figure 1. Rendering image from East view

Parametric Model Design

Among the sustainable features, Photovoltaic Car Shading Canopy was selected and designed using BIM parametric modeling techniques. This feature has been selected because of the benefit acquired by harvesting solar energy, providing shade to cars and customers, and because of the challenge to provide flexible angle of Photovoltaic panels for better energy absorption.

Modeling idea

Figure 2, 3 show possible PV CSC options for the project. Taking account the project conditions that PV canopy is going to cover partial area of parking building roof, solar panels’ angle and canopy location may vary depending on other design decisions, parametric characters of the PV CSC design are decided as follow:

Figure 2, 3. Different types of Photovoltaic Car Shading Canopy

·         PV canopy family design includes both canopy and parking areas under the roof.

·         PV panel angle is changeable by changing type property.

Modeling process

Construction process for PV CSC parametric model is as following:

1.      Design ‘h’ shaped truss that will be placed along the length of car parking area using array function to support PV panels above the cars.

2.      Array the ‘h’ shaped trusses and parking spaces according to predefined reference planes.

3.      Redefine removed constraints and define slope for the roof.

4.      Draw a roof extrusion that covers parking area and overhangs.

Diagram and equation

Diagrams are described using screen shots, and equations for the parametric model are shown in Table 1. Constructed model has one sided roof while it was sketched to have roofs on both sides of truss in the early design sketch in Figure 4 and 5.

Figure 4. Early design sketch 1

Figure 5. Early design sketch 2

Figure 6. Reference Level diagram for parametric modeling

Figure 7. Front view diagram for parametric modeling

Figure 8. Right side view diagram for parametric modeling

Table 1. Equation used for modeling 50 length & 60 angle type

Designed parametric family by types

Once parametric family is designed, four family types are defined as shown in Figure 9 to 12.

Figure 9. 50’ Length and 60° Angle type of Movable Canopy family

Figure 10. 100’ Length and 45° Angle type of Movable Canopy family

Figure 11. 150’ Length and 35° Angle type of Movable Canopy family

Figure 12. 150’ Length and 65° Angle type of Movable Canopy family

Critics about modeling application

The most important thing learned was the ‘visibility’ which is a strength Building Information Modeling technique has above previous approaches. For very innovative challenges like this project, letting project participants understand what is being designed and bringing them to the designer’s view point is very hard without showing it. However, using BIM, communication among participants can take place more easily and can be more productive. In the beginning stage of design, I was not sure about aesthetic aspect of PV CSC. However, detailed design aspects could be determined and fixed while working on the model because overall project was visualized by the REVIT tool.

On the other hand, there are some disadvantages I experienced as a BIM modeling beginner. When there were some parts of design that should be changed, it took considerable amount of time when a complicated parametric model has to be modified or there is no proper existing model. Though the strength of parametric modeling of BIM exists in the usability of the past design works, very different kind of parameters can be defined for a similar family when the usage is different. In other words, designers can use same or similar design feature of buildings once parametric design is properly constructed. This leads to fast design process and enables non-experts to generate ‘good’ models. However, construction of parametric model needs considerable amount of time and certain level of BIM skills.

In order to facilitate better use of Building Information Modeling techniques, there are things to be improved according to the project experience:

·         Design idea has to be exact and concise

·         More efficient visualization of constraints: All along the parametric design process, it was hard to recognize constraints defined for components main because it is three-dimension tool. If constraints can be visualized in ways that enhance understanding movement of components, complexity of parametric design will be relieved.


Appendix

Figure 13. Rendering image of interior space

Figure 14. Parking building entrance

Figure 15. Design view of PV canopy and parking area

Figure 16. Grocery store schematic design view from East