Managing Constraints

An Integrated Design to Construction Workflow





On a commercial high-rise tower project located in Hong Kong, the design team was challenged to make a facade that would beneficial to tenants with a panoramic view yet also harmonise with the surrounding itself. The design team comes up with a facade design which includes four bespoke conical corner facade, with a total of more than 600 units; and over 3000 shading fins with eight profile. The complexity of this project requires a more intuitive cross-platform information model to facilitate data transfer.

This paper describes a design, modelling and documentation process used to realise the 2TP tower with a cross-platform information model that extend between various tools, streamlines the early-stage design iterations, visualisation, documentation, cost estimation and fabrication. Designs processes are working our way through constraints, and they are managed within the cross-platform information model, such as limiting any oversized units to ensure at least three different manufacturers would be capable of producing cost of fabricating the units through geometrical optimisation of individual units from conical to cylindrical with an acceptable aesthetic appearance; or even software limits how the precise geometry can be modelled and document. Every constraint would be carefully included and informs the design through a quick visualisation evaluation on aesthetic and shows up on the documentation.

Through this model, which bridges between design, BIM management and construction documents, a small team is able to create, manage and produce adequate documentation that is faithful and highly precise to the design.


The practice of architecture is full of constraints, ranges from design and documentation tools to fabrication, budgets and ambitious schedules. To deliver a successful project with high complexity would require

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The 2TP tower is designed to be a triple Grade-A office tower with 195 meters tall, located in Hong Kong.

To facilitate an uninterrupted view towards the Victoria Harbour, unitized panels

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Cross-Platform Information Model

A BIM model is the culmination of a set of processes, serves to create a digital representative superset of building components used for design, fabrication and construction. (Van Der Heijden)

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Case Study – 2TP

Two different elements from the same project serve as examples of how the cross-platform information model creates an adaptable framework in preserves and generates design and construction data throughout the

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1. Shading Fins

To reduce solar gain while maintaining a high level of light transmission and visibility of the 3m wide module, variable profile external shading fins were designed. With eight profiles in

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2. Conical Corners

2. Conical Corners

The conical geometry was first designed in Rhino through visual-based scripting Grasshopper in the help with customized scripts on optimization and Elefront for data storage. Data and points

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Conclusion and Future Work

No two buildings are identical, just a no single software can complete all the task required for a project to success, the design and BIM model would unlikely be reused

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The authors wish to acknowledge and thank the team in NBBJ Los Angeles, Seattle, Hong Kong office and EOC London.

All images are provided courtesy of the author and NBBJ unless otherwise stated.

Rights and Permissions

Eastman, Charles M. BIM Handbook: A Guide to Building Information Modeling for Owners, Managers, Designers, Engineers, and Contractors. Hoboken, NJ: Wiley, 2012. Chapter 9

Al Hattab, Malak & Hamzeh, Farook,Information Flow Comparison Between Traditional and Bim-Based Projects in the Design Phase, 2013

Van der Heijden , Ramon, Levelle, Evan, Riese, Martin Parametric Building Information Generation for Design and Construction . Proceedings of the 35 Annual Conference for the Assoication of Computer Aided Design in Architect. 2015.417-429

Hong Kong SAR, Buildings Regulation (Energy Efficiency) Regulation, Cap.123M, 2012