1. MP7120 Creating BIM Models for Energy Analysis
Aryn Bergman, PE, LEED AP
Energy Analyst – TL Circle; BIM Manager - Facebook

2. Class Summary
This class will present example projects to demonstrate appropriate techniques for creating Revit models and families for energy analysis purposes:
Autodesk San Rafael HQ 111 McInnis Building – Revit model for the creating of DOE2 energy models
Rebuild Sudan’s South Sudanese Primary School project – BIM geometry for daylighting and CFD analysis in Autodesk® Ecotect® Analysis and Simulation CFD
Revit Families of Servers for Facebook’s Data Center Designs – Revit families tha are being created to represent Facebook’s servers and connect their models to a databases and spreadsheets through DB Link and the Revit API
Mention going through the power point and then doing a live demo.
Also check out the handout as it goes into much greater detail on how to create the BIM models and Revit Families.

3. Learning Objectives At the end of this class, you will be able to:
Setup project template files to expedite analysis processes
Create BIM geometry for us in energy, daylighting and CFD models
Create Revit families that can connect to databases and spreadsheets through Revit’s DB Link and API.
Link a BIM model to databases and spreadsheets

4. Autodesk University 2012 Power Track
Energy Optimization for Retrofits
MP3397-P - Taking Advantage of BIM for CFD Modeling
MP3565-P - Using a Retro-BIM Workflow: Case Studies in Energy-Driven Retrofit Projects
MP3765-P - Using BIM to Streamline Your Energy Modeling Workflows
MP3784-P - Calibrating an Existing Building Energy Model

5. Creating a Project Template File

6. Revit Families – Walls, Floors, and Roofs
Create exterior an interior walls with a standard thickness (i.e. 6”) to facilitate alignment
Specify the Function
Each envelope property should have a distinct material and color for identification purposes
Do the same for exterior floors, interior floors and roofs
Each material should have a distinct and identifiable name
Add a descriptive text to the Type Comments field for filter views

7. Metal Roofs, Ceilings, and Shading Devices
Use a ceiling family with no thickness for metal roofs if you use the model to create a CFD model
Create a family type for the walls for the vertical shading device and a family type for roofs for horizontal and angled shading devices (thickness doesn’t matter)

8. Windows, Skylights, Doors, and Openings
For windows and skylights, create families that are only openings with an extrusion representing the glazing area. Other types may cause errors in energy models and will slow down CFD model run times
Use reference planes to control the dimensions of the opening
Doors are unnecessary in energy models (not required if < 10% of overall surface area of the building per ASHRAE 90.1)
Use Windows for other openings.

9. Views
Create floor plans and 3D views under the Discipline “Architectural” so architectural elements are clearly visible and easier to select
For larger projects, create a sub-Discipline “Energy Modeling” to group views with the energy analysis geometry in the project tree
Create a view on the ground floor with Orientation set to “True North” to create the geometry in plan view, but have the ability to rotate the project to true North at any time without affecting other views

10. Views Create additional views for the space and HVAC zones
Edit the color schemes appropriately

11. Schedule Properties
Ask if which parameters would you want to list if the design team has the lights and electrical equipment’s power defined in the families?

12. Create 3D Views Create a 3D view for each building component type
The views will hide the other building components so you can export them out as a group
Allows you to manipulate the properties of each component for the entire building at the same time

13. Filters

14. Creating BIM Geometry for Energy Analysis

15. BIM for Energy Models General Rules
Don’t use rectangular straight wall openings. They’re not space bounding.
Don’t allow any gaps between architectural elements. Space object may “leak” and prevent the analysis from running.
Don’t use in-place families. Use native tools for envelope components. In-place families don’t translate to the energy analysis program.
Don’t include shaft or stairwell openings.
Don’t use design options. If you need to show design options, save them as separate models.
Don’t include columns, utility shafts or other components that don’t bind occupiable spaces.
Don’t include doors unless they cover more than 10% of the exterior surface area.
Don’t use space or room separation lines. They’re difficult to align in floor by floor and usually lead to geometry errors.

16. Energy Model Settings
Before any export is done, certain settings must be checked:
Volumes and Areas must be turned on
Edit the Energy settings (Analyze>>Energy Analysis>>Energy Settings)
Set Ground Plane.
Set Project Phase. Spaces must be placed in the same phase as the Project Information phase.
Energy Export Complexity set to Simple with Shading Surfaces. The limit of shading surfaces in the model is 1024.
Set Sliver Space Tolerance. Leave the default value of 1’ 0”.
Note: Thermal performance characteristics of elements in the Revit physical model aren’t carried through to the energy analysis programs

17. Linking Models
Orientation

18. Walls
Exterior walls should start at the ground level and extend to the roof, or another upper bounding element
Use constant thickness, different thicknesses will give you errors in your model
Model spandrel glazing as an exterior wall
Use interior walls to define HVAC zones on a floor by floor basis

19. More on Walls and Shading Devices
Don’t use interior walls as exterior walls, they won’t show up in your energy modeling program
Model underground walls separately and make sure neither the underground wall nor the exterior wall crosses the ground plane
Model curved walls as a series of straight walls and windows
Model shading devices as rectangles; use exterior walls to represent vertical shading devices and roofs for horizontal and angled shading devices

20. Roofs Roofs should all be the same thickness as floors
Offset roofs properly to that a single space could encompass the entire roof and floor slab properly
Roof should be offset by its thickness

21. Floors Floors should all be one thickness
Floor boundaries should either be the center line, or the interior surface of the exterior walls
Floors should be at the same elevation as the space
Any floor extending beyond an exterior wall should be modeled in two separate pieces; a floor inside the wall and a roof outside
Model slab on grades as exterior floors

22. Windows and Skylights

23. Ceilings
Only use ceilings when the HVAC system type utilizes the stratification effect (i.e. UFAD or displacement ventilation)
Add ceiling above the occupied volume (usually ~7’)
Set the space below the ceiling as occupied and above as plenum
Ask does anybody know why this would impact the efficiency of your HVAC system?

24. Spaces
Add one space, set the space number format and provide a common space type name (i.e. “office”).
Set the height of the space to the level above if there are interior spaces on the above floor
If the upper boundary is a roof, the top surface of the space must be offset by the thickness of the roof to avoid adding unnecessary shading devices to the model

25. Spaces
For UFAD or displacement ventilation, the top surface must align to the ceiling
Add a tag, select it and the space, and use Revit Copy (not Ctrl+C)
Revit will use the same space name and will try to guess the next space number/letter; numbers/letters will increase
Edit space types accordingly (i.e. non “office” spaces)
Use the Paste Aligned feature to copy similar space layouts from one floor to another

26. Spaces Under space properties, Select whether the space is occupiable
Select the Conditioning Type
Edit Occupancy (People)
Edit Electrical Loads
Alternatively, you can use the grouped space schedule to control the parameters for a particular space type

27. Zones Must add an HVAC zone for each space
Use the same numerical value as space number
Recommended to add an abbreviation for the space type in the zone name

28. Zone Properties Edit the Outdoor Air information
Can edit heating/cooling setpoint temperatures, but generally easier to edit these in the energy modeling tool

29. Inspect Model Geometry

30. Troubleshooting
When uploading the gbXML file created in Revit to GBS, GBS may crash and not successfully upload your model
Often, the error message won’t provide any assistance in identifying the origin of the error
To find the error in your Revit model, employ a method called “Divide and Conquer”
Start by splitting the building in half and try uploading each side to GBS
Whichever side crashes while uploading to GBS, continue splitting the model and repeat the process until you find the error
If both sides of the model crash GBS, change where you split the model.

31. Creating a DOE2 Energy Model
There are two classes at this Autodesk University the focus on the creating of a DOE2 energy model in eQUEST:
MP3765-P Using BIM to Streamline Your Energy Model Workflows by Jeff Olden
MP3784-P Calibrating an Existing Building Energy Model by Lauren Kuntz

32. BIM Geometry for Daylighting

33. BIM Geometry for Daylighting
Many projects can use the geometry created for the energy model to create a daylighting model.
In some situations, the geometry needs to more accurately represent the physical layout of the space within a building:
Slanted or other non-horizontal ceilings used for daylighting or other architectural purposes
Spaces with daylighting shelves
Projects where the impacts of furniture need to be taken into consideration
For these, create a separate Revit model and modify it accordingly
The rest of the process will remain the same

34. Adding a Slanted Ceiling
Create a level at the lowest point of the ceiling and an associated view
In that view, click on “Place Ceiling” under the Architectural tab
Set the offset to 0’ and select the top boundary of the ceiling to set the slope
Edit the slope designed at the boundary and finish the ceiling
Check in a section view to see if it has been modeled correctly; you may need to go back and edit either the ceiling’s slope or offset

35. Model Setup in Revit for Daylighting
In Revit, think about how the model is going to be used and how the geometry should be created to support that outcome
For daylighting, utilize the series of 3D views of the various building components created in the template file to isolate like materials for exporting to FBX files.
Understand the appropriate level of detail needed in the Ecotect model
Give consideration to the amount of curved/rounded objects in a model; affects file sizes and time to import geometry
Consider how these items impact furniture/major fixed equipment and file size of your model

36. Revit to 3ds Max Design to Ecotect Analysis

37. Exporting to 3ds Max Design
In the Application pulldown menu in Revit, select Export > FBX
This will export out each 3D view of like materials into an individual FBX file

38. Model Setup: 3ds Max Design
Currently, 3ds Max Design is a translator for the FBX file exported from Revit to a 3DS file imported into Ecotect Analysis
Before importing/exporting the models, ensure the project units are set up correctly
From the Customize pulldown menu, select Units Setup:
Set Display Units Scale to US Standard:
Feet w/Fractional Inches
1/32
Set System Units Setup
1 Unit – 1.0 Feet

39. Model Setup: 3ds Max Design
To import the FBX models, go to the Application pulldown menu, select Import>>Import and set Files of Type to Autodesk (*.FBX) and hit OK when the FBX Import dialog box pops up
To export, go back to the Application pulldown menu, select Export>>Export and set Save Type to 3D Studio (*.3DS) and hit save
In the dialog popup, uncheck the box for “Preserve Max Texture Coordinates”

40. Ecotect Analysis Model Imports
To import the geometry from the .3DS file created in 3ds Max Design, go to:
File>Import>3D CAD Geometry…
Files of Type: 3D Studio (*3DS, *ASC, *PRJ)
Remove Duplicate Faces
Auto Merge Triangles
Scale Objects By: Feet >Millimeters (304.8)
Material – Leave it set to <<Guess>>
Zone – Leave it set to <<File>>
Import Into Existing

41. Model Setup in Ecotect
May need to redefine the origins of your model geometry in Ecotect
This requires defining the ground plane:
Use the “Set Origin” button in the toolbar
Define a point in the model to serve as the origin
“Reset World Origin”
Go to the Modify pulldown menu
Select Transform Origin
Reset World Origin
If you didn’t specify True North in Revit, do so in the
Project Page

42. Material Assignments
To apply the specific material that has been created, go to the 3D Editor Page
In the Zone Management Panel:
Right click on a zone in the model
Right click and choose “Select Objects On”
In the Material Assignments Panel:
Select the appropriate material
Select Apply Changes
**To learn how to complete a daylighting model using Ecotect and Radiance, refer to the 2011 AU class MP4568-P by Brian Skripac

43. BIM Geometry for CFD Models

44. BIM Geometry for CFD Models
Anything hidden in active 3D view won’t be included in Simulation CFD
Use visibility graphics or the hide tool to hide categories of elements
Avoid small offsets between geometry; use join and align to eliminate small gaps
Columns and beams can generally be omitted
Fine features on furniture should be excluded (i.e. small diameter tubing, railings, rounds, fillets, holes, etc.)
All models need a surrounding mass volume to represent the air surrounding a building

45. Wind Driven Models
Where do you think the wind is coming from?

46. Buoyancy Driven Models
Does anybody know what a buoyancy driven model is?

47. Revit to Simulation CFD
Go to the 3D view where you want to use as the basis for the CFD model
Go to the Add-ins Tab and Launch Active Model
Alternatively, you can export the view’s geometry as the .sat type of CAD file and import it into Simulation CFD or Simulation CFD 360
**To learn how to complete a CFD model using Sim CFD 360, refer to the 2012 AU class MP3397-P Taking Advantage of BIM for CFD Modeling.

48. Revit Families for Linking to Databases and Spreadsheets

49. Building Revit Families
Refer to Revit’s Wiki help for detailed documentation on how to create Revit Families
Use Reference planes and Dimension Labels to adjust the dimensions of geometry

50. Connecting to an Access Database
Refer to Revit’s Wiki help for detailed documentation on how to install and use DB Link
Use Reference planes and Dimension Labels to adjust the dimensions of geometry
Limited selection of parameters that are editable in the database.

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