A BIM-based design process: 1/JBR – part 3/3

Expertise

December, 2017

Due to the data tracking for each option, it quickly became evident that keeping the design more minimal achieved better unit layouts, better efficiency, and tighter construction cost while maintaining high finish quality. At the end of pre-concept, the team had considered seven different arrangements. We discarded the most extreme options and chose one to continue into the concept phase.

This is key. Before, not after, the concept stage, the optimal arrangement of units, core, structure and services was narrowed down to one scheme, which both client and design team agreed was best.

Since so much information was available early on, the statistics didn’t change significantly in the subsequent stages.

Since the team focused on one option only for the concept phase, and since much of the design was already considered in pre-concept, this allowed a much more thorough investigation and documentation for all subsequent design stages.

Thanks to this approach, many critical design statistics became finalized in the concept stage. These included:

  • Uninterrupted views to all points of interest from every single room in each unit (excluding toilets), in 100% of the apartments.
  • A very high floor plate net/gross efficiency
  • A high Gross/Built Up Area efficiency
  • Semi-private elevator lobbies (for the lower 2/3rd of the floor plates), meaning that on these floors only two units use each lift lobby
  • Private elevator lobbies in the upper 1/3rd of the floor plates, meaning on these levels every lobby is part of the sellable area of each apartment, ensuring privacy
  • Private express lifts for both penthouses, providing total separation.

All of these criteria were achieved due to the efficient use of time from the start, thanks to the BIM design process.

In the schematic stage, the model gained a lot of detail, allowing even more accurate area calculations and cost estimates.

The size of the model at this point exceeded 250 Mb, meaning that if it were one file, it would be near impossible to work with due to the high amount of data crunching required by the server with each adjustment. This necessitated the use of work sets (a term meaning that the parts of one central model are opened in partially or entirely separate models for architecture, interiors, facade, structure, and MEP. Due to these models being separate, it is possible to edit any one of them more easily since the time required to open the model and parse the data can be significantly reduced compared to that needed to perform the same tasks on a single large model.) This is because each person worked on a much smaller model which contained only part of the overall information. Worksets also ensured disciplines could not edit each other’s files so that the design can remain intact and only be modified and adjusted by each expert team. This is significant because one of the largest time wasters in BIM is the unintentional changing of one part of the model while trying to work on another, by persons who aren’t familiar with what the other specialists in the team may be doing. Avoiding this abortive work allowed more time to focus on the best possible outcome.

Due to the early use of BIM, the end of the Schematic stage resulted in a model which had the level of resolution that comparable projects usually only have in 50% Detailed Design.

Having a lot of the small variables locked in at the end of Schematic stage allowed the team to use the Detailed Design stage to investigate the design in minute detail, optimising the model with every step.

The Detailed Design stage consisted only of detailing the agreed scheme, rather than scrambling frantically to improve the numbers.

1/JBR is going to rise out of the ground shortly. When visiting the finished product, the building will show clear evidence of an efficient design process, thanks in large part to the use of BIM in the earliest stages. The interiors are clean, minimal and elegant, while the exterior creates an iconic presence in the area.

In conclusion, I strongly recommend that designers put their schemes into BIM as early as possible. The improved decision making and efficiency resulting from this approach allow the creation of a very well-tailored building. Everyone will be doing this in a few years. I encourage everyone not to wait these several years, but rather make the effort to implement BIM in the earliest phases starting today.