In this lesson, students explore how building modeling tools can be used to the process of area and space planning, which is often one of the first steps in the preliminary design process.
Client requirements for a project are often described in area budgets that allocate square footage targets to specific departments, programs, or functions. Designers typically use these targets as a starting point for a top-down design approach, allocating specific building areas to each of the budgets and tabulating the assignments to confirm that the program needs are being met. This approach enables designers to make high-level design decisions and assess their impact, long before the details of the individual rooms are mapped out.
As preliminary design progresses, additional details are added to the building model and the initial area allocations are typically divided into rooms with specific functions and occupancies. As the design matures, area and space planning continues in parallel with the design work to ensure that each iteration of the design continues to meets the client’s needs and requirements.
Students will follow this top-down approach to first allocate the total space available within a project into areas allocated to different uses, and then subdivide these areas into rooms with specific types to meet program needs.
Defining and Displaying Areas and Area Plans
An area is a subdivision of space within a project model. Areas are typically larger in scale than individual rooms, and area boundaries may or may not coincide with model elements, such as walls.
Area plans can help monitor if all of the necessary design objectives are being met during the early conceptual and preliminary design phases, even before the room boundaries and wall have been fixed. For example, designers often use area plans in the programming phase of a project to allocate spaces to meet the budgeted space requirements for each area type. Another common application is to use area plans to show the relationship between the core and circulation spaces in a floor plan.
Area plans can be used to calculate the areas allocated to different program requirements and needs using various calculation standards and methods. Some of the commonly used standards for area calculations include:
- Gross area: The overall area of a floor or footprint of the building.
- Rentable area: Individual developers and leasing companies can use different standards and rules for computing rentable areas. For example, rentable area can be defined to include all the spaces in a building except egress corridors, vertical transportation, and mechanical spaces.
- Usable area: The area in a plan that is actually usable by clients and tenants. Usable area typically excludes areas taken up by columns, walls, mechanical rooms, and shafts and other nonusable space.
- BOMA area: The Building Owners and Managers Association (BOMA) has defined a set of definitions and area calculation rules that is widely used in the United States by architects, developers, and facilities managers to help standardize the process of office-building development. More information on the BOMA standards and calculation rules can be found at www.boma.org.
Defining and Displaying Rooms and Room Plans
As design progresses, building elements are added to the model that define and bound rooms. These elements typically include roofs, walls, floors, columns, and ceilings, and each of these elements have a property that determines whether it is used to determine the room extents. In open spaces, room separation lines can also be added to a model to create virtual rooms.
Designers typically create room objects within these bounding elements, and these room objects can be deleted, modified, and queried like other elements in Autodesk® Revit® products. Rooms automatically compute and report their area and can optionally be set up to also compute their volume. As with most other model elements, tags can be added to rooms to display their properties (such as area or volume) in plan views. Rooms can also appear in schedules to present key values and properties in a convenient tabular form.
While rooms are often used by designers for area and space planning, they are also used to provide information needed by other design disciplines. For example, they can be used for building performance analysis and design of mechanical systems. In this application, mechanical engineers use the room-bounding information as a starting point for determining spaces and zones for heating and cooling load analysis.