Attendees: David Bleiman, Victor Chu, Naveen Govind, Mario Guttman, John LeBlanc, Eric Peabody, Karen Thomas, Mark Tiscornia, Lillian Trac, Marla Ushijima
Eric Peabody presented a fantastic case study of three nearly identical projects delivered by three different processes, as the nearest thing possible to a real-world controlled experiment in BIM use. The Design Partnership (TDP) designed remodels of three operating rooms at Stanford's Cath Labs used for procedures delivered through catheterization methods. All three labs are in the same building, on the same floor.
Lab #7 was a Design Bid Build project executed in 2006 with a traditional CAD-only workflow. It started with existing 2D CAD drawings, which were verified in the field. TDP then created new 2D CAD documents for the remodeling work.
Lab #9 was a Design Assist project executed in 2009 using an "industry standard" BIM workflow which included modeling down to 2", with select smaller elements modeled as necessary. It started with a 3D scan used to create a model of the existing conditions, and then a design BIM for the remodeling work. Eric showed a very impressive image from the point cloud which many of us initially mistook for a photograph. It was black and white, but captured light reflectance of the materials. He mentioned that color scanning is also now available.
Lab #10 was also Design Assist, executed in 2010, also using 3D scanning to capture existing conditions and create an existing BIM but modeling everything for the design BIM, including studs and junction boxes.
Eric developed an extensive analysis of the three projects on the basis of schedule, change orders, and costs - design, construction, and margin (based on lost revenue from the operating rooms due to the construction). He adjusted all costs to 2010 dollars based on inflation of the economy at large (not strictly inflation of the construction economy). He deducted all medical equipment costs to level the playing field.
The design fee proposal to use BIM for Lab #9 was significantly higher than for #7 CAD - knocking the client out of their seat - but TDP lobbied successfully for it. Eric admitted that they benefited from the BIM as well, as it's in the architect's best interest to create the most coordinated set possible; but the subsequent cost savings to the client caused them to demand BIM for Lab #10. The design fees for #10 were back to the CAD level despite the increased BIM effort, because the contractor took on the modeling. That turned out to be costlier to the client due to union wages paid by the contractor. (Hmmm, perhaps architects should form a union?)
The client was also concerned about the $30,000 cost per room for the 3D scanning, but Mario points out that it is probably more than balanced by the revenue gained in getting the operating rooms back into action quicker. Some contractors such as DPR use extreme scanning procedures, repeatedly scanning as the building rises to confirm accuracy. Dave notes that vertical coordination of floor penetrations is critical for Total Station Control methodologies. He also notes that DPR's emphasis on precision offers marketing opportunities.
Post-construction, Lab #7 drawings had to be revised to match as-built conditions. Lab #9 BIM was close enough that the client didn't require revisions. Lab #10 BIM was virtually identical to the as-built conditions.
TDP's conclusion after these three projects is that BIM definitely beats CAD, the 2" standard of Lab #9 is a little coarse, but the "model everything" approach of Lab #10 yields diminishing returns. TDP determined the sweet spot as modeling to 1-1/2", which is sufficient to capture all the necessary medical gas lines and struts.
Mark feels that contractors are getting to the point that
they want no change orders to the virtual model. He proposes that if
designers model the same way as contractors, there's more likelihood
that the design model doesn't need to be thrown away. If the contractor
can start with the design model then he should be able to reduce his
fees.
Dave notes that everything is Design Assist now, there's very
little Design-Bid-Build. In Europe structural designers do the shop
drawings and provide a book of quantities. This process is facilitated
by the Parts tool introduced in Revit 2012.
On the issue of code review and BIM submittal for permits, Singapore was mentioned but Mario and Dave repeated their belief that it remains largely apocryphal. As long as paper drawings remain necessary for permitting, especially for OSHPD, they must remain the basis of contract documents. This is, of course, at odds with contractors who derive much greater value out of the BIM. As models increasingly become the professional standard of care, it becomes more difficult legally to rely on disclaimers regarding their accuracy. A more appropriate approach to accuracy issues might be to establish clearly-defined Levels of Development. Designers are also wise to hyper-link the specs to elements in the model to keep critical information on the contractor's radar. This also adds potential value to the model post-construction for use by facility managers and building management systems.
Dave suggests that to stay in the game designers must create greater value for ourselves. We need to be prepared to rely on the BIM as contract documents. An in-house QA process for models becomes critical.
Eric notes that in Europe a new category of professional is emerging who's responsible for BIM modeling and analysis (energy, lifecycle costs, etc.).
In the U.S., we noted the trend toward acquisitions. As firms such as AECOM are merging diverse professionals of varying core competencies, authoring and ownership of a BIM - plus the associated liability issues - become moot as it's increasingly all done in-house. Pankow and Herrero have also purchased some of their own sub-contractors. We questioned whether mid-size firms are dying out as partnering becomes necessary for success or even survival.
