December 3, 2014
Matthew Kennedy

Question:  What do Frank Gehry, a car salesman and healthcare planners all have in common? 

Answer: Parametric Design

First, let me explain what I mean by parametric design. Simply put, parametric design is a design approach that uses a list of form-generating criteria, or rules, resulting in creation of a three-dimensional building form that responds to the list of criteria and the associative impact the list of multiple criteria have upon one another.

For example, a designer may be tasked with designing a room with a floor area between 120 and 160 square feet, with a skylight that has an area one quarter the size of the total floor area. If the total area of the skylight falls below four square feet,  a window of similar dimensions should replace the skylight. As you may realize from this rudimentary example, parametric design requires specialized design software where a user can input the criteria to which a design should respond, which the specialized software then uses to generate a variety of three-dimensional design options that meet the stated parameters. This approach can be used to quickly generate highly-complex forms not easily achievable through standard design methods alone. It also allows one to change certain dimensional inputs or the like, while the design software maintains the relationship of the various parameters and makes adjustments to stay within these rules and display the resulting new form.

The typical result of this process is easily seen in the architectural work of someone like Frank Gehry. His iconic buildings – such as the Walt Disney Concert Hall or the Guggenheim Museum – are prime examples of the parametric design process and reflect the trend in how parametric design processes are utilized to make such form-rich buildings easier to model and develop, easier to study and analyze, and even easier to construct – making them a more achievable reality.

But where do car salesmen come in?

A good car salesman will ask you what your wants and needs are, (i.e., establishing your criteria) and will then generate several new car options that meet your criteria to achieve a sale.

I’ll admit that this last example stretches the definition of parametric design, but this blog is meant to highlight some of the unconventional uses of parametric design for healthcare design, or more specifically, for healthcare planning where healthcare planners (the third group from our quiz question above) are often challenged to develop a solution of function rather than form. Where the highly publicized capabilities of parametric design for developing complex three-dimensional forms are flattened to address the planning issues faced by healthcare planners in the two-dimensional context of a floor plan.

The quiz question asked above is meant to make you think along a different track.  Following are two examples where parametric design is utilized in a different fashion, to generate an architectural form based on parameters associated with function, instead of form alone.

A common issue among healthcare planners is the reconciliation of internal functional demands to external design requirements. For example, to hide the end-wall locations where interior walls abut exterior ribbon glass of the exterior curtain wall, planners typically adjust room widths so that the end-walls can be hidden behind opaque panels of spandrel glass or intersect where a window mullion is located. This is easy to do when designers set window elements like mullions and spandrel glass at regular intervals along a façade, and planners also organize similar width rooms, like exam rooms, on the exterior wall. However, at Central Hospital for the University of Montreal (C.H.U.M.), the designers had decided that the exterior fenestration was going to take on a texturized character, where the use of clear-vision glass panels and spandrel glass panels were to be randomly located to create more of a textured aesthetic for the curtain wall. Planners also organized office and other support areas of differing room sizes along the exterior wall, which provided better internal functional organization, but resulted in additional complexity when trying to match internal wall locations with spandrel glass locations of the external design.

The reconciliation between these complex systems easily could have led to numerous conditions where multiple construction details would need to be developed to avoid conflicts, but would have added costs and construction time. However, utilizing parametric design software with criteria established during the planning phase of the building, such as room areas, wall locations and floor-to-floor heights,  a systematic solution was developed to marry the existing wall locations to the appropriate use of spandrel glass, where interior walls abutted exterior glass. The resulting design pattern optimized the number and complexity of panels needed to accomplish the task from over 25 end conditions down to 5 conditions to detail – despite 15 floors of varying wall conditions and over 1,500 unique room sizes and locations. This produced a random, yet aesthetically pleasing and functionally efficient result, otherwise difficult to model and achieve without the use of parametric design.

Another explorer of this flattened world of parametric design is Sumandeep Singh, architectural designer and former healthcare exchange fellow in the HKS New Delhi office.

Sumandeep has developed a parametric design tool merging use of available off-the-shelf software to allow users to create and study multiple plan options for nursing units. This new software tool allows him to model these options directly in front of the client/end users, so that a variety of plan options can be quickly viewed and approved for further design development.


The tool takes a ready-made plan option, such as a typical acute-care unit where patient rooms are organized along a single loaded corridor/central support core layout or Racetrack design. At this stage, Sumandeep can vary common two-dimensional design parameters, such as typical room depths and proximity requirements between rooms, like the patient room and central nurses’ station, or even model other traffic flows within the framework of the parametric software to allow dynamic modeling of resultant plan options. The results allow a healthcare planner to come up with a variety of different combinations of plans for discussion with the client for potential approval – quickening development of planning the optimal patient care unit, meeting the end-user's specific needs in real time and in plan view and altering all the adjacent spaces to better address the parametric criteria.

The possibility inherent in this tool and other equally dynamic tools, ones that utilize parametric criteria based on required function rather than three-dimensional form elements, is that they can complement that which we already use today. Healthcare planning is very heavy on function, and having the ability to utilize parametric design can have a great time-saving effects on healthcare design.

Here are some additional thought starters in regards to parametric design:

  • Testing the possibility of assembly line manufacturing of patient rooms by visualizing the space in a three-dimensional, parametric design tool and providing improvement parameters in the form of code and 3D printing its various components. (Source: Sumandeep Singh; “Parametric Design Tools for Healthcare Design”)
  • Examining the planning efficiency of a patient ward with the help of mathematical algorithms directly fed into the visual design tools, using computer code like Visual Basic. VB is already a part of the grasshopper package and currently is being used by very few architects in their design process. The future generation needs to be ready to learn coding as a basic in their architectural education. (Source: Sumandeep Singh; “Parametric Design Tools for Healthcare Design”) 

Here are some useful links for more information: - Parametric Design – India: - Parametric Design Tools for Healthcare Design - Exploring parametric modeling, BIM and Design Technology for new forms of craft Grasshopper manual - Design - Optimization - Fabrication D-O-F - the analysis of design - open design research platform - soft/rigid behavior in architecture - place for sharing ideas

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