--- title: "Which Rack Layout Does the Model Quantity Describe? Design Options and Project Phases" description: "Leviathan Systems — Technical content Published 2026-10-20; updated 2026-10-20." canonical: "https://www.leviathansystems.co/articles/revit-design-options-project-phases-rack-layout-quantities" last-updated: "2026-10-20" --- # Which Rack Layout Does the Model Quantity Describe? Design Options and Project Phases Leviathan Systems — Technical content Published 2026-10-20; updated 2026-10-20. Define the layout alternative and project time state before using a model-derived rack quantity. Revit 2026 design options describe alternative solutions; project phases describe periods in the project's life. A useful comparison identifies both selections and demonstrates which objects its quantities include. Objects retained for another alternative, items proposed for removal and newly proposed items can all belong in project information without belonging in the same purchase quantity. ## Define the design choice and the time state A rack-layout comparison can contain accurate arithmetic and still answer the wrong question. One output may count the proposed final arrangement for Layout A. Another may include an earlier arrangement, removal work or objects belonging to Layout B. Comparing their totals as competing rack requirements would conceal the different populations behind the numbers. Two selections come first. Which design solution does the output represent? At what stage of the project does it represent that solution? Choosing Layout A does not identify a phase. Choosing a future phase does not select A over B. A comparison of a selected layout still needs to distinguish continuing, removed and new objects. Hold the time state constant when comparing alternative layouts. Hold the layout choice constant when comparing stages of its development. If the comparison intentionally changes both, explain both changes before attributing a quantity difference to the layout. The same principle applies whether the recipient receives a model view, a schedule or a separate quantity document. References: [A1](https://help.autodesk.com/cloudhelp/2026/ENU/Revit-Model/files/GUID-D48D9BCE-DCD2-444A-8AD3-472F725164A6.htm), [A3](https://help.autodesk.com/cloudhelp/2026/ENU/Revit-DocumentPresent/files/GUID-BDCE1B94-58D0-401B-863B-2708D36D54EA.htm) ## Read the option set before treating its contents as a requirement Autodesk's Revit 2026 terminology defines the main model as the building-model content outside design options. An option set groups possible solutions to a particular design problem. Each option is one solution; one option in the set is primary, with the others secondary. Separate option sets can address separate problems, so a comparison involving several sets needs the intended choice from each relevant set. For a rack-layout study, the useful distinction is between common content and the content that changes with the alternative. The main model is not another competing layout to add alongside every option. Nor does retaining several alternatives in the same project establish that the project needs to install all of them. The documented default view shows the main model with the primary option. Revit also supports views dedicated to other options, and Autodesk states that a project view displays only one option from each set. Primary describes the preferred option within the software's option set. It is insufficient evidence of which alternative a particular issued comparison or purchasing decision uses. Identify the intended option explicitly and relate that choice to the delivered output; do not infer it from whichever arrangement happens to appear when the file opens. References: [A1](https://help.autodesk.com/cloudhelp/2026/ENU/Revit-Model/files/GUID-D48D9BCE-DCD2-444A-8AD3-472F725164A6.htm), [A2](https://help.autodesk.com/cloudhelp/2026/ENU/Revit-Model/files/GUID-F2B110FD-8643-476C-9DD6-C5BF5C8E71FE.htm) ## Count four common racks plus one alternative Consider an original fictional set example. Four rack objects belong to the main model. A single option set contains Layout A with six additional rack objects and mutually alternative Layout B with eight. The three groups are distinct objects. Hold the phase, counting unit and all other eligibility conditions constant, and stipulate that every rack in the chosen arrangement belongs in the comparison. No model or schedule was executed. For A, the intended population is the four common objects plus A's six: ten racks. For B, it is the same four common objects plus B's eight: twelve racks. The alternatives differ by two racks under these assumptions. B's eight are its alternative contribution, not eight additions to A's ten. All three stored groups contain eighteen rack objects in total. That is a count across the fictional project's alternative representations, not the rack requirement for either chosen layout. The error would be interpreting that undefined mixed population as a purchase quantity. This example does not claim that a Revit schedule automatically returns eighteen. A comparison can correctly repeat the four common racks in both the A and B totals because each total describes a complete candidate arrangement. Adding those two comparison totals would count the common group twice and combine alternatives. Ask the team producing the comparison to account for the four common objects and the chosen six or eight in the actual requested output. A bare total cannot demonstrate that membership. ## Interpret phase status relative to the represented time Revit 2026 phases represent time periods in a project's life. Autodesk documents Phase Created and Phase Demolished properties for elements, and Phase and Phase Filter properties for views. The view's phase and the element's phase properties work together to establish its phase status in that view. Status is therefore relative to the represented stage, rather than a permanent label describing what an object is. The phase-filter documentation distinguishes an element added in the current phase, one continuing from an earlier phase, one removed in the current phase after earlier creation, and one both added and removed within that phase. These correspond to new, existing, demolished and temporary statuses. An element can be new in one phase's view and demolished in a later phase's view. A phase filter controls which statuses are displayed and how they appear. A view communicating removal work can intentionally include objects absent from the planned completed arrangement. Their presence is useful information; their inclusion in an end-state rack total would answer a different question. Autodesk also documents applying phases to schedules to produce phase-specific documentation. That supports asking for a defined time state in a quantity deliverable. It does not establish the behavior of every proposed rack category, schedule, linked model or export. Have the model author demonstrate the intended output in its actual environment. References: [A3](https://help.autodesk.com/cloudhelp/2026/ENU/Revit-DocumentPresent/files/GUID-BDCE1B94-58D0-401B-863B-2708D36D54EA.htm), [A4](https://help.autodesk.com/cloudhelp/2026/ENU/Revit-DocumentPresent/files/GUID-602AB1FE-6C10-4A80-BD74-76ED77D4B601.htm), [A5](https://help.autodesk.com/cloudhelp/2026/ENU/Revit-DocumentPresent/files/GUID-DB104358-4D5A-494E-ACAE-BB8B4E72E572.htm) ## Five future items can include only two additions Use a separate fictional time-state example, independent of the ten-rack and twelve-rack alternatives above. Before the work, four rack items are represented. Exactly one of those four is proposed for removal during the work phase. The other three remain, and two new items are proposed. Assume no temporary items or other changes. The planned population after that work is four minus one plus two: five items. Within the work phase, the example has three continuing Existing items, one Demolished item and two New items. Calling all four original items Existing in that phase would obscure the one assigned for removal; four is the pre-work population. Each quantity answers a useful question. Four describes the starting arrangement. One describes the removal population. Two describes additions. Five describes the planned end state, consisting of three retained items and two additions. A package concerned with the work can legitimately describe all those relationships, but they cannot be collapsed into one unexplained rack count. In particular, five future items does not mean five new items to buy. Even the two proposed additions need their actual supply and allocation basis before becoming an order quantity. Conversely, one modeled removal is not evidence that removal has happened. The represented state and observations of the physical installation need separate evidence; naming a phase or marking an element demolished does not supply that evidence. ## Review the population in the output the buyer will receive Before commissioning the complete comparison, ask for a representative return that makes the alternative and time state recoverable. The team producing it should identify the model issue, relevant option set and selected option, represented phase, included statuses and counting unit. A reader needs to know whether the number describes the completed arrangement, new work, removal work or another deliberately defined population. Then review membership in the actual deliverable. In the layout example, the A return should account for the four common racks and A's six, while explaining B's exclusion from that result. In the time-state example, a completed-state return should account for the three retained items and two additions. If the requested quantity arrives in an exported document, review that document as well as the source view. A screenshot beside a spreadsheet does not establish that both describe the same objects. These are information requirements for the team producing the comparison and its recipient to demonstrate, rather than instructions for changing a model. Agree the target software version and the actual schedule or exchange scope. Where linked content participates, its intended option and phase treatment also needs confirmation; host-view appearance alone does not establish the linked population returned in another output. Other quantity mechanisms retain their own roles. The separately schedulable rack-components guide explains shared nested families and the distinction between instances and displayed rows. The cable-schedule and BOM guide explains material units and included contents. Resolving those questions does not select the layout or phase for this comparison, and selecting a layout does not resolve those questions. ## Bring the layout comparison to the planning inquiry Leviathan's Physical Infrastructure Planning & CAD service is the existing place to discuss rack layouts, routing coordination, schedules and material-documentation requirements. Describe which alternatives need comparison, the project stage each output should represent and whether the next recipient needs an end-state count or the additions and removals that produce it. Use the project inquiry below to explain the required comparison and the authorized inputs available. Actual authoring software, production resources, supported outputs and review responsibilities are confirmed for the engagement before a native Revit deliverable is committed. A clearly defined population gives that scope discussion a useful result to pursue. ## Primary sources - [A1 — Autodesk Revit 2026 Help — Design Options Terminology](https://help.autodesk.com/cloudhelp/2026/ENU/Revit-Model/files/GUID-D48D9BCE-DCD2-444A-8AD3-472F725164A6.htm). Checked 2026-10-20. Defines the main model, option sets, individual options, primary and secondary options. Supports distinguishing common project content from alternative solutions. - [A2 — Autodesk Revit 2026 Help — View Design Options](https://help.autodesk.com/cloudhelp/2026/ENU/Revit-Model/files/GUID-F2B110FD-8643-476C-9DD6-C5BF5C8E71FE.htm). Checked 2026-10-20. Documents the default main-model and primary-option display, dedicated alternative views and one displayed option per set. View behavior does not establish a project's issued choice or a particular quantity export. - [A3 — Autodesk Revit 2026 Help — About Phasing](https://help.autodesk.com/cloudhelp/2026/ENU/Revit-DocumentPresent/files/GUID-BDCE1B94-58D0-401B-863B-2708D36D54EA.htm). Checked 2026-10-20. Explains phases as project time periods and phase-specific documentation, including schedules. Its schedule illustration concerns doors, rather than demonstrating a rack-family output. - [A4 — Autodesk Revit 2026 Help — About Phase Properties](https://help.autodesk.com/cloudhelp/2026/ENU/Revit-DocumentPresent/files/GUID-602AB1FE-6C10-4A80-BD74-76ED77D4B601.htm). Checked 2026-10-20. Explains element creation and demolition phases, view phase and filter properties, and their relationship to phase status. Relevant to interpreting a represented time state. - [A5 — Autodesk Revit 2026 Help — About Phase Filters](https://help.autodesk.com/cloudhelp/2026/ENU/Revit-DocumentPresent/files/GUID-DB104358-4D5A-494E-ACAE-BB8B4E72E572.htm). Checked 2026-10-20. Defines new, existing, demolished and temporary statuses and describes display filters. The fictional rack arithmetic states its own populations and is not a reported software result. ## Related Leviathan resources - [Physical Infrastructure Planning & CAD](/services/engineering-design) - [Specify separately schedulable rack components](/articles/gpu-rack-revit-family-schedulable-components) - [Reconcile cable schedules and material quantities](/articles/cable-schedule-vs-bom-data-center) - [Define the Revit or IFC output the recipient needs](/articles/gpu-cabling-revit-ifc-deliverable-brief) ## Define the Rack Layout and Time State Your Quantities Must Represent Describe the alternatives, project stages and quantity output your team needs so we can discuss the physical planning scope, available authoring capability and review requirements. [Discuss the scope](/contact?service=engineering-design&from=/articles/revit-design-options-project-phases-rack-layout-quantities)