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Envelope Thermal Properties in Revit and Insight

Introduction:

In Revit, you can customize the thermal properties of the wall, window, floor, and roof constructions to accurately reflect the materials that you would like to use in your design. These detailed properties can be exported in your energy model to be used as the As-Modeled Values in Insight by enabling the Detailed Element checkbox in the Advanced Energy Settings.

Using these detailed element thermal properties produces a more accurate energy model rather than simply relying on the Conceptual or Schematic Types.

 

This video shows the workflow for changing the and running an energy model analysis using Detailed Elements.

Workflow Steps:

Open a Project

Set Energy Settings

  • On the Analyze tab, select Energy Settings.
  • Verify that the Use Building Elements mode is selected.
  • Open the Advanced Energy Settings, for Other Options, by clicking Edit.
  • Confirm that the Export Category is set to Spaces (if they are defined in your model).

Enable Detailed Elements Thermal Properties

  • In the Advanced Energy Setting dialog, check the Detailed Elements checkbox.

The Detailed Elements option pulls thermal properties from the constructions used in Revit, overriding the thermal properties of both Conceptual and Schematic Types. If a construction does not have thermal properties assigned in the model, Revit will assign properties to an element from either the Conceptual Type or the Schematic Type (if one is defined for the category).

  • Click OK twice to apply Energy Settings changes.

View the Thermal Properties for a Wall Type

  • Open the default 3D view.
  • Click on an exterior wall in your model.
  • Click the Edit Type button in the Properties palette.
  • Note the thermal properties listed for this wall type in the Analytical Properties section of the Types Properties dialog.

These thermal properties are determined by the materials in the structure of the wall type and their thicknesses.

Create New Wall Types with a Different Material Thickness

  • Click the Duplicate button to create a new wall type.
  • Enter a new name. For example, Exterior-EIFS on Mtl. Stud – Extra Insulation.
  • Click OK.
  • Click the Edit button in the Structure cell of the Properties palette.
  • Note the Resistance (R) and Thermal Mass at the top of the Edit Assembly dialog box.
  • Change the thickness of the EIFS, Exterior Insulation layer from 3’’ to 4’’.
  • Note how the Resistance and Thermal Mass values changed as you increased the thickness of this layer.
  • Click OK to save this assembly.

Create New Wall Type with a Different Material Type

  • Click the Duplicate button again to create another wall type.
  • Edit the name to Exterior - EIFS on Wood Stud – Extra Insulation.
  • Click OK.
  • Click the Edit button in the Structure cell of the Properties palette.
  • Click the action button at the right end of the Metal Stud Layer cell in the Material column.
  • Search for Structure, Wood Joist/Rafter Layer, Batt Insulation in the Material Browser window.
  • Double click on this material name to enter in to the assembly.
  • Note how the Resistance and Thermal Mass values increased again as you changed the material in the stud layer of the wall.
  • Click OK to save this assembly.
  • Click OK to close the Types Properties dialog.

Assign Thermal Properties by Changing Wall Types

  • Select any wall in your model.
  • Open the Type selector in the Properties palette to assign a wall type with the desired thermal properties to that wall.

You can use similar steps to create new types for wall, roof, floor, and ceiling assemblies with structures that model their thermal properties.  Then, select the building elements and choose the new types from the Type selector in the Properties palette to apply them to the elements.

Warning: If you create or modify a building element trying the thermal properties associated with it, use realistic assumptions.   Unrealistic assumptions can lead to errors, causing the analysis to fail. ( See Use Detailed Elements for Material Thermal Properties)

Generate Insight

  • Go to the Analyze tab and click Generate.
    • If the energy model has not already been created, accept the prompt to create it now.
    • If the energy model already exists, choose whether to use the existing model or generate a new one.

If the energy simulation failed at this stage check the thermal properties of the building envelope elements and try simplify them with fewer layers or smaller thickness.

Access Results

  • Once the Insight analysis is complete, go to the Analyze tab and click Optimize to access the results in the Insight interface.

The analysis results will use the detailed thermal properties specified, and the As-Modeled data point for the Wall Construction and Roof Construction factors will reflect the values of the selected wall and roof types.

 

Exercise:

Follow the steps outlined below:

  1. For the first simulation, open the E1a_Schematics model in Revit
  2. Open the Location tool and set Project Location
    • Change Project Address to Minneapolis, MN
    • Select Weather Station 32579
  3. Run the energy analysis
    • Set the Energy settings to the following:
      • Mode: Use Building Elements
      • Building Type: Retail
    • Generate Insight
  4. For the second simulation, open the E2a_Detailed model in Revit
  5. Open the Location tool and set Project Location
    • Change Project Address to Minneapolis, MN
    • Select Weather Station 32579
  6. Run the energy analysis
    • Set the Energy settings to the following:
      • Mode: Use Building Elements
      • Building Type: Retail
    • Generate Insight
  7. For the third energy simulation, change all the roofs
    • Save the project as E2a_Roofs.
    • Access Energy Settings
      • Make sure to select Spaces as the exporting category
    • Change all the roofs to “Concrete Deck - Tapered Insulation”
    • Generate Insight
  8. Go to Insight.
  9. Create Insight to compare models
    • Create a new Insight and add the last three submitted models to this Insight for comparison.
    • Open the Insight you have just created by selecting the tile.
  10. Open one of the models and create the baseline
    • Set a range or value for the following factors:
      • Operating Schedule: 12/6
      • Lighting Efficiency: 0.3 - 0.7 W/sf
      • Plug Load Efficiency: 0.6 W/sf
      • HVAC: ASHRAE Heat Pump
    • Save this scenario and rename it as Baseline
  11. Select Back to Insight
  12. In the Model Comparison panel, select the baseline scenario and compare the performance of simulation.
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