How Revit Effectively Handles Volume Challenges in Cavities, Shafts, and Wall Grooves

How Revit Addresses Volume Issues in Cavities, Shafts, and Wall Grooves

Accurate heating and cooling load analysis requires the correct identification of internal and external room boundary elements. Ideally, space components should be assigned to voids, shafts, and wall grooves whenever possible. However, some areas may be too small to accommodate a dedicated space.

In such cases, there are two methods to account for the volume of these small spaces:

• Clearing the Wall Tangent to Another Space: By clearing the room boundary parameters of the wall shared with an adjacent space, the volume of the small area is included in the neighboring larger space.
• Adjusting the Small Gap Space Tolerance: This method treats these small areas as small gap spaces. Any areas smaller than the defined tolerance are automatically merged into the volume of adjacent spaces.

The size and shape of these small areas determine which method is most appropriate.

To clear the room boundary parameters:

1. Go to Modify → Room Boundary → Parameters.
2. Select the walls between the main space and the small area.
3. In the Attributes panel, under Restrictions, uncheck Room Boundary.
4. Click Apply.

Once done, the shading of the adjacent space will fill in these small areas, and their volume will be automatically included in that space’s total volume.

Repeat this process for all similar small areas in the model. Note: When working with linked models, remember to clear the room boundary parameters in the linked files as well.

Alternatively, you can handle small gap spaces by adjusting the tolerance settings:

1. Go to Adjust Model → Small Gap Space Tolerance. Refer to the guidelines on small gap spaces before proceeding.
2. Compared to clearing room boundary parameters individually, adjusting the small gap space tolerance for the entire model is usually safer and more efficient.

To determine the appropriate tolerance:

1. On the Annotation tab, under the Dimensioning panel, select Align.
2. Measure the centerline spacing of the walls enclosing the small gap space.
3. Next, go to the Analysis tab, open the Report and Detailed Table for heating and cooling loads.
4. Within the Heating and Cooling Loads dialog box, under the Regular tab, set the Small Gap Space Tolerance to a value equal to or greater than the measured wall centerline spacing.

The image below illustrates a model prepared for load analysis. On the left is the floor plan, while the right shows the analysis model within the Heating and Cooling Loads dialog box.

All symmetrical and asymmetrical areas have been assigned spaces, including built-in components located at the model’s openings. The space on the far left does not qualify as a small gap space because there is no adjacent space beyond the exterior wall.

Room boundary parameters have been cleared for the partition wall between this area and the adjacent space, as well as for the partition wall between the curved area and a small rectangular area below within the project.

After clearing these parameters, the affected areas are shaded and become part of the adjacent space. Although small gap spaces are not shaded in the floor plan view, they appear in the analysis model and their volumes are included during heating and cooling load calculations.

【 Related Skills 】

Revit Analysis and Design: Heating and Cooling Load Analysis

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