Specifying Energy Analysis (gbXML) Settings

You can define gbXML settings that can be used for Energy Analysis for Autodesk® Revit®, as well as third-party energy analysis software.

Before performing Energy Analysis for Autodesk® Revit® or exporting to gbXML

The following parameters must be specified prior to performing Energy Analysis for Autodesk® Revit® for Revit, exporting the building model to a gbXML file for use with a third-party energy analysis application or performing heating and cooling loads analysis:

• Building Type - specifies the type of building according to the gbXML schema 0.37 (similar to ASHRAE).
• Location - specifies the geographic location and weather for the project. Click , and in the Location Weather and Site dialog, specify the location and weather. See Specifying the Project Location.

  You can specify location by selecting a city or by entering longitude and latitude values. The location establishes the climate and temperatures used in loads calculation.

• Ground Plane - specifies the level that serves as the ground level reference for the building. Surfaces below this level are considered to be underground. The default level is zero.
  Note: Ground plane does not affect Heating and Cooling Loads calculations. It is used with gbXML export.
• Export Category - determines whether rooms or spaces are exported. Selecting rooms or spaces determines which options below are available.
• Export Complexity - specifies the level of detail provided for openings, and whether shading surface information is exported. Shading surfaces are surfaces that are not adjacent to any space, and include surfaces that create a solar obstruction. Only used with Energy Analysis for Autodesk® Revit® or Export gbXML. Simple complexity is used for heating and cooling loads analysis.
  • Simple - curtain walls and curtain systems are exported as a single opening (without individual panels). Simple is more appropriate for energy analysis.
  • Simple with shading surfaces - same as simple, but with shading surface information exported.
  • Complex - curtain walls and curtain systems are exported as multiple openings, panel by panel.
  • Complex with shading surfaces - same as complex, but with shading surface information exported.

    Shading surfaces are not associated with any room/space (roof overhang, free-standing wall).

  • Complex with mullions and shading surfaces - same as complex, but with mullion and shading surface information exported.

    Mullions in curtain walls are exported as shading surfaces. A simple analytical shading surface is produced from mullions, based on the centerline, thickness, and offset.

• Include Thermal Properties - If Export Category is set to rooms, select this option to export thermal properties to gbXML.
• Project Phase - specifies the stage of construction (Existing, New Construction).
• Sliver Space Tolerance - specifies the tolerance for areas that will be considered sliver spaces.

  See Accounting for the Volume of Cavities, Shafts, and Chases.

If Export Category is set to spaces, the following options are available:

• Building Service - specifies the heating and cooling systems for the building.
• Building Construction - specifies the type of construction, which determines the materials and insulation (U-values) for the building.
• Building Infiltration Class: Specifies an estimate of outdoor air that enters the building through leaks in the building envelope.
  Note: Infiltration is not exported to gbXML.

  Infiltration can be specified as:

  • Loose - 0.076 cfm/sqft for tightly constructed walls.
  • Medium - 0.038 cfm/sqft for tightly constructed walls.
  • Tight - 0.019 cfm/sqft for tightly constructed walls.
  • None - infiltration is excluded from the calculation of loads.
• Export Default Values - determines whether certain default values will be exported. When checked, the default values for People and Electrical Loads, Occupancy, Lighting, and Power Schedules, and building/space type Construction Types are exported together with all user specified values. When cleared, only user-specified values are exported. Only used with Export gbXML.
• Report Type: Specifies the level of information provided in the heating and cooling loads report. You can specify Simple, Standard, or Detailed for Report Type.

You can optionally specify information about construction elements, such as windows and doors, and interior and exterior wall, floors slab, roof, and ceiling, construction.

To specify gbXML settings

1. Click Manage tabSettings panel (Project Information).
2. In the Instance Properties dialog, click Edit for the Energy Settings parameter.
3. In the Energy Settings dialog, do the following:
   • For Building Type, select one of the predefined values.
   • For Location, specify the Specifying the Project Location.
   • For Export Category, select Rooms or Spaces.
   • For Project Phase, select Existing or New Construction.
   • For Sliver Space Tolerance, specify a tolerance value for sliver spaces. All areas that are within the sliver space tolerance are considered sliver spaces.
   

   Other sliver space conditions must also be satisfied for an area to be considered a sliver space. See Placing Spaces.

   • Enter optional construction parameter values.
4. Click OK twice.