Tips for Improving Energy Model Creation

• Revit uses the following elements (when set to room-bounding) to create the energy model:
• Ceilings
• Columns
• Curtain panels
• Curtain systems
• Curtain wall mullions
• Doors
• Floors
• Mass
• Roofs: common edges, hidden lines, interior edges, roof soffits
• Shaft openings
• Structural columns
• Walls: common edges, hidden lines
• Note: Inaccurate energy analysis results may be generated if your model contains slanted or elliptical walls.
• Windows
• To isolate elements
• Create a new 3D view of the model.
• In the view, set Visibility/Graphics overrides to display only the elements listed above, including subcategories where specified.

Maximize the accuracy of the energy analytical model and minimize processing time by making adjustments to the architectural model.

• In the 3D view, identify any elements that lie outside the building itself and have no impact on building energy.
• For example, if you used floors to model roads or paths, or walls for landscaping that is outside the building, adjust them using of these approaches:
• Select these elements, and disable the Room Bounding property.
• This will omit these elements from the energy analytical model creation process.
• To hide these elements in the view, right-click them and select Hide in View.
• This helps to minimize processing time required to create the energy analytical model.

To create an energy analytical model from an architectural model, the building elements must be reasonably enclosed.

• The model does not need to be watertight. Small gaps and overlaps are natural part of real architectural models. They are expected and allowed during the creation of the energy analytical model.
• However, if an entire roof is missing over a space or a wall is missing or a large gap exists (greater than one to two times the Analytical Space Resolution setting), the issue should be addressed.

Do this:

• Orbit the 3D view and look for obvious missing elements or large gaps in the overall envelope.
• Check the model all the way around, above and below.
• Not all gaps are easily spotted. Don't expect to find them all in this step. Just check for anything obvious.
• Address any obvious omissions or gaps.

• Click Analyze > Energy Optimization panel > Create Energy Model
• A message explains that creating the energy analytical model may take considerable time, during which Revit is unavailable.
• In the dialog, select Create the Analytical Model.
• When the energy analytical model is ready, the Energy Model is displayed in the Analytical Spaces view.
• To view the Analytical Surfaces:
• Duplicate the Analytical Spaces view.
• Open the Visibility/Graphics dialog, and switch to the Analytical Model Categories tab:
• Turn off Analytical Spaces.
• Turn on Analytical Surfaces.
• Verifying Shading Surfaces

Shade surfaces occur when any Revit architectural element (or part of it) lies outside the main paths of building heat transfer, such as the parapet of a wall or the overhang of a roof. Shade surfaces should appear only where they make sense.

1. To check the accuracy of shading surfaces:
• Turn on the Shades subcategory.
• Turn off all other Analytical Surfaces subcategories.
2. Examine the view, looking for shade surfaces that exist where they do not belong.
• When you find an unexpected shade surface, go to this area of the architectural model to examine it more closely, looking for gaps or missing elements.
• Pay attention to elements whose Room Bounding property is disabled. These elements are not considered during the creation of the energy analytical model, so they may be the cause of the incorrect shades.
• Address any issues that you have identified.
3. Regenerate the Energy Analysis Model to confirm that the changes improved the model.

After ensuring the energy analytical model contains all required analytical spaces and that all analytical surfaces are located appropriately, examine the model for gaps between elements.

Small gaps between energy analytical model elements are expected and do not have a negative impact on the analysis. If these gaps are large, however, or reasonable sections of the building are not fully captured, you must reduce the Analytical Space Resolution and Analytical Surface Resolution settings. This change increases processing time. It may also uncover more gaps or omissions in the architectural model.

• Look for Large Gaps
• In the 3D Energy Model view, open the Visibility/Graphics dialog.
• On the Analytical Model Categories tab, do the following:
• Select Analytical Spaces.
• For Analytical Surfaces, select all subcategories.
• Orbit the energy analytical model, looking for unexpectedly large gaps between elements.
• If you find large gaps, do the following:
• Click Analyze tabEnergy Optimization panel (Energy Settings).
• In the Energy Settings dialog, change Analytical Space Resolution to 1' or 457.2 mm, and change Analytical Surface Resolution to 6" or 152.4 mm.

Keep these parameters in a ratio of roughly 2:1. The minimum values are 6" and 3" (152.4 and 76.2 mm). Resolution settings of 8" and 4" (203.2 and 101.6 mm) are typically effective for most detailed architectural models.

• Create the energy analytical model and reassess the results, iteratively adjusting the Analytical Space Resolution and Analytical Surface Resolution settings until you are satisfied with the energy analytical model.