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Last edited 15 Sep 2020
The term 'design intent' is an ambiguous one with several different possible meanings.
ASHRAE Guideline 1-1996, The HVAC Commissioning Process, defines the term 'design intent' as '…a detailed explanation of the ideas, concepts, and criteria that are defined by the owner to be important'.
It suggests that this is developed before the design process begins and sets out what the 'owner' thinks is important. It defines the engineer's scope of work from the owners perspective and may be developed by the owner in conjunction with the engineer. Setting out intent in this way provides a mechanism by which subsequent proposals can be assessed to verify whether they satisfy the intent.
 Early design stages
The term 'design intent' is sometimes used to refer to early design decisions, that is, what the designer intends to design. This has resulted in a whole range of documentation prepared in the early stages of a project being marked as 'design intent', when in fact they just set out preliminary design thinking.
 Designer's intent
Designer's intent may refer more specifically to drawings and other information prepared by the project team that convey the fundamental, intrinsic requirements of a design. Where drawings go beyond showing just these basic requirements and include more detail, they might be referred to as working drawings.
Shop drawings are then prepared by contractors, subcontractors, suppliers, manufacturers or fabricators. These take the design intent drawings and other information and develop them to show in detail how the component will actually be manufactured, fabricated, assembled or installed.
PAS 1192-2:2013 Specification for information management for the capital/delivery phase of construction projects using building information modelling (BIM) (now replaced by BS EN ISO 19650) suggests that during the design process, the initial version of the building information model developed by design suppliers might be described as the 'design intent model'.
This should show, '…the architectural and engineering intentions of the design suppliers'. Then, when ownership of the model is transferred to the construction suppliers, it is developed into a virtual construction model containing all the objects to be manufactured, installed or constructed.
Parametric modelling (or parametric design) is the creation of a model based on a series of pre-programmed rules or algorithms known as 'parameters'. That is, the model, or elements of it, are generated automatically by internal logic arguments rather than by being manually manipulated.
It is important when using parametric modelling that the 'design intent' is clearly understood and properly defined so that if an element changes, the design intent remains intact. For example, if a junction needs to be in the middle of an element, it needs to be expressed that way, rather than as a fixed dimension from an edge, because if the size of the element changes, the junction needs to remain in the middle, rather than the original distance from the edge.
NB The RIBA Plan of Work published by the RIBA in 2020 defines descriptive Information (or design intent) as: ‘The means by which the design team describes a Building System in a manner that allows a specialist subcontractor to design the system.’ For more information see: Descriptive information
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