Glossary of VDC Concepts and Terms
Activity: identifiable work to be performed by an actor using a set of resources to complete an identifiable activity in a process. Actors and process tasks together define an Organization-Process model.
Assessed Behavior: Measure of goodness of the predicted/observed behavior value, given its sated functional objective requirement. Arbitrarily, this value is in the range 0:3, where 0 represents an unsatisfactory value; 1 is marginal; 2 meets stated objective and 3 exceeds objective (if it is possible to do so).
Behavior: predicted or observed measurements about an aspect or element of a design. Behavior is a major segment of POP models. Behaviors are predicted or measured performance of the product, organization and process. For
- product, performance of the physical elements and systems, e.g., capacity, cost, quality;
- organization, performance of the teams, e.g., cost, latency, backlog;
- process, performance of the tasks, e.g., schedule, cost, reliability.
CD (Construction Document): See Project Phases
Conformance: percentage agreement of planned and measured schedule, cost or quality data. A good project has high measured daily or weekly conformance (> 80%) of planned 2 or 3-week lookahead schedule to actual schedule performance. “Plan Percent Complete” (PPC)” is another term for schedule conformance.
Controllable Factor: a condition that a designer or manager can actually control, such as a design choice about a product, the choice of what teams and people to hire, and the design of a work process. Controllable factors affect process performance and project outcomes.
Dependency: the precedence dependence represents the information or time relationship between two or more activities in a process, which we formally model in the Critical Path Method (CPM) plan or activity precedence diagram. A dependent activity cannot start until the independent ones finish, or at least complete a pre-specified "enough." Additional types of activity dependency include information and rework: two (parallel) activities might need to share information, and failure in one might require rework in another. Dynamic and complex projects often have more complex dependencies than simpler projects.
Design Space: given the the design parameters that relate to a set of project objectives and goals, design space is the set of possible options that meet objectives and requirements of a specific project. Exploring a design space means evaluating the various design options possible with a given range of possible product, organization and process designs and optimizing with respect to project objectives and constraints such as required spaces and cost.
DD (Design Developmen): See Project Phases
Digital Build: synonym for VDC model of the project. A VDC modeling team constantly generates digital builds as a project progresses. Digital builds evolve as product, organization and process designs evolve throughout the design and construction phases. Digital builds are then tools for integrated project teams to describe, predict, explain and evaluate project design as well as to assess the need for additional design, construction, integration, coordinating, management and validation efforts.
Form: See Scope
Function: requirement for a project that must be met because it is intent of an owner or comes from a municipality or usual design practice. Function drives choice by the design team of Scope. The designed and ultimately the built scope in turn affect the behaviors of design, construction processes, such as schedule and cost, and the then operations, such as energy use. Function is a major segment of POP Models.
Function applies to Product, Organization and Process, for example:
- Product: physical elements and systems, e.g., walls, spaces and HVAC
- Organization: teams, e.g., design, engineering, construction, operations
- Process: tasks to design, build and operate that are the responsibility of teams
Design synthesis creates a design, or design forms, given a specification of functional intent. See Scope.
ICE (Integrated Concurrent Engineering): a way to organize a design team that enables stakeholders from multiple disciplines to participate concurrently to develop integrated project designs very rapidly.
LOD (Level of Detail): a measure of the complexity of a model. The most abstract (“Level-A”) have about one element in each major section; about ten elements in each major section in Level-B, and increasing in detail in higher levels.
Objective Weight: Functions have specific objectives. For overall project success, Objective weight (arbitrarily integer values with a sum total of 100), represents the relative weight or importance of each objective of the Product, Organization and Process.
Organization model: model of the Actors in a project and their responsibilities, as well as actor attributes such as size (number of people), skills, and percentage availability over the project period. The OBS definition informs the design of the organization scope of the POP model and the details of the organization model. The organization scope typically involves elements of the OBS.
POE (Post Occupancy Evaluation): the quality of a project by affected stakeholders
POP Model: representation -- at a high level -- of the Functions, Scope and Behaviors of the Product, Organization and Process of a project. Each POP model names the shared or related vocabulary used in the Product Model, Organization Model and Process Model. Each of these more detailed models has its own data.
Process: Activities and procedures followed by an organization team to create a product, i.e., the work the organization does, or a statement of “what we plan to do.” Plan activities are statements of the work to do including precedence relationships among activities, and Schedule activities have a planned start and end. Activities have responsible actors; they may have coordination and rework dependencies that identify the other activities with which they must coordinate or that must initiate rework if an individual activity encounters some sort of failure. POP models represent the Functions, Scopes and Behaviors of project Processes.
Process Model: explicit description of the tasks of a project with their precedence and information and rework dependencies. Task attributes include work volume, task complexity and required skills. The WBS definition informs the design of the process scope of the POP Model and the details of the Process Model.
Product: the physical or abstract deliverable of a project as the organization follows the process, typically a building, facility or design. POP models represent the Functions, Scopes and Behaviors of project Products.
Product Model: explicit description of the abstract systems (e.g., HVAC), spaces (e.g., rooms and elevators) and physical elements (e.g., walls, columns, beams) of a physical facility. Physical model element attributes include dimensions and materials. The PBS definition informs the design of the product scope of the POP model and the details of the product model.
Process Performance Metric: an aspect of project performance that a team can measure frequently (hourly, daily or every week or two) and use to judge how well past management choices (see Controllable factors) are moving toward the final project outcome objectives.
Production Planning and Control: management of the prefabrication and construction operations to be performed by different teams over a particular time period. Production control involves periodic (e.g., bi-weekly) physical meetings for product and process coordination and integration. Control considers the availability of materials, resources and schedule requirements.
Project Definition: a process that clarifies and aligns: Functional objectives – what project stakeholders want – for the product, organization and process with Scope, or what the project will do -- periodic design and construction deliverables, and Behaviors – with what the project predicts and does, i.e., predicted and observed project performance.
Project Outcome: an aspect of a project that is important and normally can be known only at the project completion, such as final quality, cost, schedule and safety. Outcome follows process performance and in turn controllable factors.
Project Phases: traditional AEC phases include pre-project planning, which obtains budget and initial zoning approvals; early Schematic Design (SD), Design Development (DD), which adds system issues to the design, and Construction Document preparation (CD), which is the final design phase. Design is followed by Construction, Commissioning and Occupancy.
Qualitative Threshold Values: values that define quantitative ranges for good, marginal and unacceptable behavior parameter performance. For example, the functional design team might specify Assessed value of a parameter such as Safety is given a value using the following rules:
- 0 (Red light status) if predicted behavior value >= C threshold
- 1 (Yellow) if B <= value < C
- 1 (Green) if A <= value < B
- 2 (Green) if value <= A
- Product, i.e., actual physical elements and systems designed in response to product functional requirements
- Organization, i.e., actual teams to do tasks to design, build and operate the product, which are designed in response to organization functional requirements
- Process, i.e., tasks to design, build and operate that are responsibility of the teams, designed in response to process functional requirements
Scope is a major segment of POP models. Design theory sometimes uses the word form for this concept. Design has the following steps:
- Specify the Function, or the intent of the physical, organizational and process elements of the project and the objectives for specific behaviors, e.g., cost, schedule, quality and risk or reliability;
- Synthesize or create the design scope (of the Product, Organization and Process), given the function;
- Analyze the designed scope to predict its behaviors;
- Evaluate the predicted behaviors to check whether they meet objectives stated in the function;
- Iterate to synthesize different options or, if necessary, change functional objectives until the design is complete.
Measures of success are that, at any level of detail, the
- Designed scope follows stated functions;
- Product elements and systems have organizational teams to design, build and operate them;
- Process tasks exist to design, build and operate the physical product
- Process tasks have responsible teams and teams have one or more tasks to do
- Predicted behaviors of the Product elements meets functional objectives.
SD (Schematic Design): See Project Phases
Stage of VDC implementation: VDC emerges incrementally. Normally the first stage is visualization to support understanding and decisions of an individual project team, then systems based integration of multiple models to facilitate description, explanation, evaluation and prediction of their behaviors, and finally as automation of significant portions of design and construction activity.
Target Costing: A structured approach to determine the life-cycle cost at which a proposed solution with specified functionality and quality must be produced to generate the required return on investment. See Wikipedia.
Variability: a measure of the non uniformity of a process. Duration variability exists in all project production systems due to variability in inherent task complexity. It has a tremendous impact on design and construction performance, therefore, measuring, understanding its sources, and managing variability is key to effective production management in projects.
Virtual Design and Construction (VDC): the use of integrated multi-disciplinary performance models of design-construction projects to support explicit and public business objectives. Ideally, VDC models include related a Product Model, an Organization Model and a Process Model.
Virtual Model: a model in the computer of some aspect of a project. Virtual models can complement and often replace physical models, and they can be built long before the actual product, organization or process emerges in real life. Our experiences are that if a team cannot build a project in the computer, it cannot build it in real life, and that building virtual models can significantly decrease project risks.
Visualization: presenting a model in a way that is meaningful to diverse stakeholders, which is normally visual, such as a 3D model of a product, a network of actors and activities for organization and process models, and time-based (4D) animations of product construction as well as time graphs of building performance.