BIM Tutorials: Revit Spatial Data Management

The spatial information of a project is important information for the GSA, property owner, and the AE. The importance of this data can not be understated, it is one of the primary drivers in GSA's adoption of BIM. The information below describes the elements, information and process to complete this vital data.

Required Materials

Several documents are required to properly generate the spatial information for the GSA. Here are the required documents for review.

• ANSI/BOMA Standard Method for Measuring Floor Area in Office Buildings (ANSI/BOMA Z 65.1 – 1996)
• PBS Business Assignment Guide
• GSA P100
• GSA 3D-4D-BIM Overview
• GSA Spatial Validation Program
• PBS CAD Standards

Any questions that arise, establish a meeting with the GSA Project Manager (PM) and Regional BIM Champion to discuss the questions and get clarification for the project being worked on.

Revit Areas and Revit Rooms/Revit Spaces Overview

GSA uses the Revit Areas and Rooms/Spaces objects to hold the spatial information associated with the project. This information is a required deliverable found within project and the GSA model checker checks this information during all phases of the project. Below is an overview of Areas, Rooms and Spaces objects in Revit.

Revit Areas (2D object)

An area is a subdivision of space within a building model, typically on a larger scale than individual rooms. However, areas are not necessarily bounded by model elements. You can draw area boundaries or pick model elements to use as boundaries. When you add model elements, the area boundaries do not necessarily change automatically. You can specify how area boundaries behave:

• Some area boundaries are static. That is, they do not change automatically and must be changed manually.
• Some area boundaries are dynamic. They stay connected with underlying model elements. If the model elements move, the area boundaries move with them.

Revit Room (3D object)

A Revit Room is a subdivision of space within a building model, based on elements such as walls, floors, roofs, and ceilings. These elements are defined as room-bounding. Revit refers to these room-bounding elements when computing the perimeter, area, and volume of a room. In Revit, you can turn on/off the Room Bounding parameter of many elements. You can also use room separation lines to further subdivide space where no room-bounding elements exist. When you add, move, or delete room-bounding elements, the room’s dimensions update automatically.

Revit Space (3D object)

Rooms and Spaces are independent components used for different purposes. Rooms are architectural components used to maintain information about occupied areas. Spaces are exclusively used for the MEP disciplines to analyze volume. They contain parameters that maintain information about the areas in which they have been placed. This information is used for performing a heating and cooling loads analysis. The phase of the space must match the phase of the room. In a linked model, the phase of the space must match or correspond (if it has a different phase name) to the phase of the linked room. Spaces can be placed (added) and unplaced, and deleted. Unplacing spaces is not the same as deleting spaces. Spaces are immediately assigned to the Default zone when they are initially added to a project. Spaces can be viewed in a section view. Spaces cannot be viewed or placed in elevation or 3D views. Spaces should be placed throughout the model, including unoccupied areas such as plenums areas. Spaces that are created (manually or automatically) in an area that contains a room are created as occupied (Occupiable parameter selected). When placed in an enclosed area, the volume for a space is calculated to the surfaces of room-bounding components, such as walls, floors, ceilings, roofs, and space separation lines. The volume for the space expands horizontally and vertically to the extent of the face of the room-bounding components. Surfaces fall into one of two categories:

• Exterior - Except when the component’s type parameter, Function, is specified as Interior or Core/Shaft, surfaces for room-bounding components (such as walls) have spaces tangent on one side only, or they have no spaces tangent and are treated as exterior surfaces. Heating and cooling loads analysis treats these surfaces as exterior, even if they are interior.
• Interior - These surfaces for room-bounding components that have spaces tangent on both sides are treated as interior surfaces or components whose type parameter, Function is specified as Interior or Core/Shaft.

When spaces are not placed throughout the model, internal walls can be incorrectly identified as exterior walls, which results in an inaccurate heating and cooling loads analysis. The only exception is when the type parameter, Function, is specified as Interior or Core/Shaft for the room-bounding component.

GSA Spaces (Revit Areas)

Key Schedules

To assist in the input of area information, a series of key schedules has been created to help automate the data entry. Several entries will be filled out when the key parameter is entered. Before working with areas, please review these schedules in the project.

• PBS AB KEY
• PBS ANSI.BOMA CATEGORY KEY
• PBS SPACE CATEGORY
• PBS SPACE NAMES KEY
• PBS SPACE SCHEDULE
• PBS SPACE TYPE KEY

GSA Space Object (Revit Rooms & Revit Spaces)

GSA has created a series of project based parameters to complete the spatial information needed for rooms and spaces. These parameters correspond with information found at GSA BIM Series Guide 02 – Section 2, pages 19 – 23. Below is a list of GSA area parameters found in the GSA provided Revit templates.

Key Schedules

To assist in the input of area information, a series of key schedules have been created to help automate the data entry. Several entries will be filled out when the key parameter is entered. Before working with areas, please review these schedules in the project.

• GSA OCCUPANT KEY TABLE

Spatial Information to IFC

Click image to open expanded view.

The Industry Foundation Classes (IFC) data model is intended to describe building and construction industry data. It is a neutral and open specification that is not controlled by a single vendor or group of vendors. It is an object oriented file format with a data model developed by buildingSMART (International Alliance for Interoperability, IAI) to facilitate interoperability in the building industry, and is a commonly used format for Building Information Modeling (BIM). The IFC model specification is open and available. One of the requirements of the GSA is to provide an IFC (2x3) model by the AE. It is important to note that Revit Areas do not export to IFC, but Revit Rooms and Revit Spaces do.

Procedure - GSA Spatial Program Validation

To generate GSA Usable Area information:

1. Generate an Area Floor Plan
   1. Make it "Rentable"
2. Select the Area
3. In element properties, fill out the following entries:
   1. Space Name
   2. Space Category Code
   3. ANSI.BOMA Category
   4. Space Type Code
   5. AB Code
   6. Building Specific Room Number
   7. CBR Number
   8. Building Number
   9. Architectural Room Number
   10. Required Area
   11. Area Type

To generate GSA Net Area:

1. Select Room or Space tool
2. Place Room or Space
3. Select Room or Space
4. In element properties, fill out the following entries:
   1. Room Style
   2. Occupant Organization Name Key
   3. Occupant
   4. Space Category Description (See Key Schedule "PBS SPACE CATEGORY KEY" for possible entries)
   5. Space Type Description (See Key Schedule "PBS SPACE TYPE KEY" for possible entries)
   6. AB Name (See Key Schedule "PBS AB KEY" for possible entries)
   7. AB Short Name (See Key Schedule "PBS AB KEY" for possible entries)
   8. ANSI.BOMA Category Description (See Key Schedule "PBS ANSI.BOMA CATEGORY KEY" for possible entries)
   9. Architectural Room Number
   10. Room Name