Archive for November 24th, 2010

November 24, 2010

Revit and CFdesign

Moving to Building Information Modelling does not just assist in the co-ordination and production of plans and elevations. With an accurate 3D model, simulation and analysis can lead to better designs. Blue Ridge Numerics has recently hooked up its Computational Fluid Analysis solution, CFdesign, to Revit, writes Martyn Day.

Computational Fluid Analysis (CFA) sits at the high-end of the design analysis technology tree. It plays a major role in aircraft and automotive design, providing feedback about airflow and reducing drag. It similarly assists the aerodynamic design of Formula 1 cars, with access to wind tunnels limited by the regulations of the competition. However, CFD is not limited to just those cutting-edge professions, but has regularly been used by high-end engineering construction firms and consultants for many years.

With the focus of building design now largely pointing towards greener buildings, maximising efficiency and lowering energy usage, architects have a need to understand the physics of their designs. Like solar, lighting and heating analysis tools such as Autodesk’s Ecotect, CFD can play an active role in shaping the conceptual form, which is decided early in the design process. Putting analysis at the back end of a design process, if at all, when all the key decisions have been made and documented is a fundamental design-process error.

CFD can emulate gases and liquids, heat and mass transfer, multiphase physics, fluid-structure interaction and acoustics throughout any meshed 3D computer model. The move to Building Information Modelling (BIM) in the industry is providing the essential raw material for analysis and 3D models. For architects, a CFD solver would help solve traditionally tough design challenges: thermal comfort, energy audits, solar loading, condensation, smoke egress, occupant safety, thermal bridging and external wind loading. It is due to the increasing need for accurate physical modelling and the consequences of design decisions that Blue Ridge Numerics has built an integration between CFdesign and Autodesk’s popular Revit design suite.


Revit offers the potential to build a single digital model of a design, from the initial concepts to a full building, containing all the Mechanical, Electrical, Plumbing (MEP) and structural components. At each design phase, CFD tools have an active role to play.

On installing CFdesign 2010, a CFdesign icon is added to the Revit toolbar. When an analysis is required simply click on the icon and the design study manager window is brought up. Here one selects which geometry is allocated to the various simulation options. Once selected, CFdesign launches with the corresponding geometry, where various simulations can be run to analyse the airflow, heat, smoke and a number of other possibilities. With each change to the design, the geometry can be resubmitted to CFdesign for analysis. As the design progresses, the CFD analysis will provide valuable feedback on the performance, indicating problem areas that need to be addressed or are introduced by design teams or client changes.

CFdesign displays two wind analyses of the faces of a building side by side, showing the velocity magnitude profile for the design. Results like this will quickly alert the designer to any issues that can be rectified early in the conceptual design phase.

For instance, at the initial concept stage, the wind pressure may be a concern. A 3D model, with or without terrain, can be exported directly into CFdesign, together with weather information for the location. The more geometry that is imported the longer the analysis will take, so elements like trees or small building details should not be selected for export for quick ‘what if?’ scenarios.

As this is the first version of the link, CFdesign only deals with the geometry, ignoring any additional building information that Revit holds, this is expected to be leveraged in future releases.


CFdesign is a very rich visual package and pretty easy to use. The thermal and airflow results are provided in colour-banded 3D models, which feature all the forces or temperatures on building surfaces together with arrow and ribbon animations, indication of wind speeds, directions and any currents or vortexes that the form generates.

The software provides results in a graphical feedback with many options for how to display the results, arrows, ribbons, animation and a variety of graphs, which can immediately provide clear feedback for design refinement. The results are projected onto the 3D model in CFdesign and they can be interacted with and the view can be manipulated. It is even possible to bring up the 3D solutions of two different analyses side by side, which is really useful when trying to understand the results or the effectiveness of proposed solutions.

From my experience I have seen firms use CFD analysis for conceptual design of complex tall buildings that have louvre systems for shading. Obviously in a city and at considerable altitude, the louvre systems need to stay attached to the building and not buckle under extreme wind loads. Here, a CFD analysis can give critical and accurate feedback to determine the loads that any design will have to survive.

CFD is complex as there are many levels of interaction, together with the complexity of fluid physics. In this example it is not just the interaction between the airflow and the louvre, or the air and the building skin, but also how the surrounding buildings impact the airflow prior to reaching the building’s envelope. When considering large-scale analysis such as these, CFD is also used in pollution analysis, as well as the wind deflection impact of new building designs to existing buildings.

CFD tools can model the movement of hot and cold air for thermal emissions and MEP analysis. This can be used in the simulation of residential, commercial and industrial building scenarios, including natural solar heating as well as heat from equipment like servers and PCs. Obviously, CFD is highly useful for simulating the cooling and heating provided by MEP systems. Here complete high-efficiency heating, ventilation and air-conditioning (HVAC) building systems can be simulated and the complex interactions between airflows understood, which will hopefully minimise building running costs.

HVAC and MEP analysis is where CFdesign really excels. Here a floor at Yale University has been analysed as built. The colour mapping shows the lack of consistency in the coverage. The analysis depicted next to it is after this information has been used to optimise the ducting design, providing consistent coverage.

CFdesign offers excellent tools to simulate the effect of smoke from a building fire throughout a model, as demonstrated on page 20. This will help establish the visibility in the event of a fire and any design changes that could be made to give occupants the maximum possibility of escaping.


Historically, CFD solutions not only cost tens of thousands of pounds, but also have typically been licensed per year and at additional licenses per individual processor. Blue Ridge Numerics has a reputation for bucking that trend and have brought the price of CFD down, but it is still a significant investment of many thousands of pounds.

I would envisage an architectural firm having one licence of CFdesign, which would be used by multiple teams as a central resource, providing quick design results, as well as more detailed analysis as the design progresses. Should the practice be mixed with MEP, then that is more users and more benefit from the investment.

The move to 3D in design construction is still in its early days but is now starting to benefit from years of research in other design fields. While the AEC 3D modelling tools are now reaching a mature and usable level, in only a matter of years, high-end, bullet-proof analysis tools are now available for enhanced iterative design.

CFdesign is a very, very impressive tool, its results are as visually appealing as Autodesk’s Ecotect and intuitive to use. The comparison function and design-test-edit methodology will undoubtedly lead to rapid improvements in the creation of performance-driven, energy efficient buildings.

Written by Martyn Day

Published 25 January 2010

November 24, 2010

Rhino Grasshopper

Popular among students and professionals, McNeel Associate’s Rhino modelling tool is endemic in the architectural design world. The new Grasshopper environment provides an intuitive way to explore designs without having to learn to script, writes Martyn Day.

Generative modelling is undoubtedly becoming one of the most exciting CAD developments adopted by the industry. While architectural practices lagged mechanical designer’s appetite for 3D by about 20 years, there has been a sharp increase in the use of 3D and advanced form-creation tools and Rhino is one of the more popular solutions.

Zaha Hadid’s Guggenheim Hermitage Museum, Vilnius. This will be the new centre for international art house pieces from collections of both the New York-based Solomon R. Guggenheim Foundation and the St Petersburg-based State Hermitage Museum.

Rhino has played a predominant role within that move to 3D because of its low cost, ease of use and powerful feature set. Bob McNeel, the man behind McNeel and Associates, developer of Rhino, estimates that it possibly has around 50,000 architectural users worldwide. However, Rhino is developed to be a non-industry specific surface modelling tool, at home designing a yacht, a ring, a shoe or a skyscraper it produces surfaces that are useful for all designers.

McNeel has developed a number of Rhino add-ons and plug-ins, mainly offering additional broad-functionality for rendering and animation in the guise of other animals ‘Penguin’ and ‘Flamingo’, as well as ‘Bongo’ and ‘Brazil’. The latest enhancement is called Grasshopper and comes free of charge while it is in development. Aimed at the emerging generative shape designers, Grasshopper is tightly integrated into Rhino and allows the user to interactively drive geometry via a plug and play interface, removing the need for learning the RhinoScript language.

Bob McNeel said that Grasshopper was developed as an attempt to make scripting more accessible to users that wanted generative modelling tools. “During the design process, designers set-up sophisticated relationships between the parts of the design problem. Before Grasshopper, Scripting, .NET, or C++ code was the only way to do that in Rhino. Writing code is not something designers really want to get their head into. It seemed like most bigger firms have a few ‘scripting geeks’ that could not keep up with the designers’ demands. So more and more designers were asking for scripting training… but then they hated it once they figured out how tedious coding was.

“Grasshopper is a way for designers to look at design problems as a set of sophisticated relationships and to map those relationships graphically and programmatically into a system that allows them to interactively play with alternatives. At first Grasshopper was very simple but, based on user feedback, it now allows for very complete systems, including the ability for expert users to extend the system with C# and Visual Basic components.”

Grasshopper works within Rhino and uses standard Rhino geometry but has its own slick interface window. Algorithms and manipulators are dragged, dropped and connected, as if they were being wired together like effects pedals. It is about as easy as it gets to use but still requires a methodology and understanding of geometry to get a desired result.

Rhino in London

Rhino is particularly popular with expressive London-based architects, such as Zaha Hadid, Buro Happold, HOK Sport and Foster + Partners. Fostering Grasshopper’s usage in London is SimplyRhino, the largest Rhino reseller.

The company runs the annual Shape to Fabrication event which focuses on the use of Rhino and Grasshopper in modelling forms and shapes, through to complex engineering analysis and final manufacturing. McNeel programmers and even Bob McNeel usually make an appearance and are very accessible. The Simply Rhino Shape to Fabrication events are always complete sell outs and well worth attending.

Grasshopper works within Rhino and uses standard Rhino geometry but has its own slick interface window. Algorithms and manipulators are dragged, dropped and connected, as if they were being wired together like effects pedals.

Globally, Bob McNeel knows of 12,000 active Grasshopper customers, 90% of which are architects but admits there may well be more as users do not have to register to download. This liberal attitude permeates through McNeel’s business model and means the company is very customer focussed, leading to a very active user community.

One of the stand-out messages from Grasshopper was McNeel linking the modelling to fabrication. While other CAD vendors seem to only concentrate on the modelling aspect in creating the 3D forms, McNeel has always talked about what happens once the design is complete. “Our assumption is that Rhino is all about ‘design for digital fabrication’. Rhino has always been about free-form shapes that are accurate enough to manufacture. Architecture is the only market we are in that still requires complete 2-D documentation. In all of the other markets, the Rhino 3-D model is used in all phases of design through to fabrication. In many cases without any 2-D documentation.

“AEC is only beginning to catch up. Many of the limitations are not related to the CAD technology, instead the problem is with the AEC business model where everyone is trying to protect themselves from being sued by the other members in the process. Lucky for us, free-form architecture has become very fashionable and it is not possible to fabricate those buildings from 2-D drawings alone. In general, I would guess that more than half of all Rhino users are on the fabrication side rather than the design side.”

Grasshopper is being used and talked about by the same people that had advanced geometry needs and bought into Bentley Systems’ Generative Components (GC). However, GC is script-based and requires training. It is also based on MicroStation, which has a parametric modeller, while Grasshopper uses a very visual plug and play interface to automate the scripting and is based on Rhino, which is a non-parametric surface modeller.

Bob McNeel admitted that the company does not know much about GC, “except that people tell us that it is harder to learn and use than Grasshopper. Since Grasshopper is very flexible, users can set up most any kind of relationship they like, so I guess you could say some of those relationships are parametric. But if the user wants to organise their generative model more like a script, it is more script-like. We are trying not to limit anyone’s shape generation process by forcing them to think about it in a certain way. In most cases, Grasshopper is instantly interactive when you change an input (geometry or parameter) or when you change the definition.”


One of the biggest limitations of all parametric modelling tools is performance, it is very easy to create a script that forces the computer to make thousands of calculations and slow down. The shipping 32 bit version of Rhino suffers from the 2GB RAM limit. To access 64 bit it is suggested moving to the ‘work in progress’ Rhino 5 builds that are available. Bob McNeel explained the strategies to limit performance degradation: “Our goal is for the generative process to be completely interactive. If you make any change to the Grasshopper definition or an input, you see the change instantly. Of course, as the definition gets more complex and the model larger, it slows down. There are options to not regenerate every time you make a change. Also, it is easy to ‘disconnect’ part of a definition while you are working on others.”

The Mac

McNeel has said that Rhino is available as a ‘work in progress’ for the Apple Macintosh and it may be some time before Mac customers will be able to use it. “Grasshopper is a .NET application. It is not clear how we will be able to get Grasshopper over to OSX. The Rhino for OSX is still in development and we haven’t addressed any of the issues related to plug-ins yet,” said Bob McNeel.


Rhino has always been an impressive modelling tool but with Grasshopper, it becomes a very powerful design exploration conceptualiser. The interface for developing the generative designs is worthy of an ‘ease of use’ prize and shames established products like Bentley’s Generative Components. However, users still need to know what they are doing and how to get what they want from the geometry mathematically. The amazing work of Grasshopper users speaks volumes.

While Grasshopper is currently free, it may incur a cost in future. “Grasshopper is still in development. It will be free to all Rhino users as long as it is in development… at least another year. We are not sure yet if at some point it will be an option, or included with Rhino, or a special version of Rhino, or there is a basic version with Rhino and a full version option! In any case, it will not be a financial burden to anyone that wants to use it,” said Bob McNeel.

McNeel has recently launched a new website for the Grasshopper community, which offers tutorials, a gallery and an active forum.

Written by Martyn Day

Published 02 June 2009

November 24, 2010

modeLab | Advanced Parametrics Workshop

Advanced Parametrics is a two-day intensive design workshop (with an optional third day) to be held in New York City during the weekend of December 04.

This workshop will cover advanced parametric topics such as data structure manipulation as well as design strategies that incorporate Simulation and Genetic Algorithms in a fast-paced and hands-on learning environment.  An optional third workshop day is offered to those participants desiring further time to develop individual projects or lines of research.

Rhino, in conjunction with the parametric modeling plug-in Grasshopper and its multitude of add-ons, offers the possibility to explore parametric and computational design with unprecedented fluidity. Leveraging this capacity, we have structured this workshop around a series of architectural design strategies with supporting content to foster a fast-paced and productive learning environment. As part of a larger online infrastructure, modeLab, this workshop provides participants with continued support and knowledge to draw upon for future learning.

Attendance will be limited to provide each participant maximum dedicated time with instructors. Participants should be familiar with the basic concepts of parametric design and interface of Grasshopper.

modeLab is graciously supported by the following sponsors:


Instructors | Ronnie Parsons + Gil Akos | Partners, Studio Mode.
All experience levels are welcome. Participants should be familiar with the basic concepts of parametric design and interface of Grasshopper.
All participants are required to bring their own laptops. Trial software will be made available.
Registration Pricing (limited enrollment) : $550/$650.
Workshop Location :  modeLab | NYC.
Workshop Hours : 10AM-6PM.
Examples of Previous Workshops.

modeLab Workbook | Printed + PDF Documentation
modeLab Exercises | Annotated Pre- and Post-Exercise GHX Files
modeLab Primers | Annotated Primer GHX Files
modeLab Strategies | Annotated Parametric Strategy GHX Files
modeLab Utilities | Custom Parametric Design Workflow Utility GHX Files

Parametric Design Logics
Computational Geometry
Modularity + Recombination
Data Structures + Manipulation
Simulation + Genetic Algorithms

2010.November.01 | Workshop Announced + Registration Opens.
2010.December.04 | Workshop Begins.
2010.December.06 | Optional Workshop Session.

To register for the workshop, please complete payment through the button below.

Registration Options
2Days $550.00 3Days $650.00


November 24, 2010

Pedestrian bridge for La Roche-sur-Yon by Bernard Tschumi and Hugh Dutton

A pedestrian bridge designed by American New York-based architectBernard Tschumi and French firm Hugh Dutton Associés has opened in La Roche-sur-Yon in France.

The tubular lattice bridge connects the old centre of Atlantic coast town with newer districts across the TGV railway tracks.

Photos are copyright © Christian Richters/VIEW

Here’s some info from the architectural team:


LA ROCHE-SUR-YON, FRANCE March 9, 2010: A public ceremony on February 6th inaugurated a footbridge in La Roche-sur-Yon, France, designed by Bernard Tschumi Architects and Hugh Dutton Associates. The bridge’s cylindrical structure aims to express the loads and stresses on the bridge while creating an original and contemporary statement for the town, located near resort communities of the western coast.

The extension of the TGV train to La Roche-sur-Yon and nearby towns bordering the Atlantic marks not only an important moment for the modernization of the European and French train network, but also  an occasion to initiate civic improvements.  Linking the historic city founded by Napoleon (“the Pentagon”) with new neighborhoods, this pedestrian bridge crosses above high-speed railway tracks, providing an important urban connection for the town.

Conceived through joint collaboration between the fields of architecture and engineering, the bridge was designed by Bernard Tschumi and Hugh Dutton, with their respective teams in Paris and New York.  The teams developed the design for La Roche-sur-Yon as both a utilitarian vector of movement and a symbol of contemporary urban relationships.  The intention of the designers was to demonstrate an integration of an original structural system with an architectural concept developed from urban scale research of neighborhood identity and carried through the expression of the minutest details.

It has been said that there is no architecture without movement.  A pedestrian bridge is not just a static object, but represents a dynamic vector in both its usage and urban perception.  The designers have sought to express this dynamic characteristic, as much through the structural system as through finishing materials (interlaced polycarbonate surfaces protect passengers from weather conditions, while lighting follows the rhythm of the structure).  Even the bright red-orange color was chosen to emphasize the urban significance of the bridge as a pedestrian vector.


The new bridge replaces an existing structure, a standard railway design that can be found all over France, contemporary with and inspired by the work of Eiffel, using lateral beams composed of a diagonal mesh of small plate strips that are riveted together.  The design of the new bridge uses the same language of a diagonal mesh, but in a tubular from, to create a complete cylindrical volume through which the users pass. Footbridges over railways require lateral protection for safety of both the users and the trains below. The complete volume provides a single structural solution that possesses the necessary inertia to span between the available support points as well as provide support for the required protective screens and a canopy cover.

Robert le Ricolais, a distinguished thinker and innovator in architectural and engineering design was born in La Roche-sur-Yon, worked in France before World War 2 and then moved to the University of Pennsylvania. He is known for his research work in the development of spatial three dimensional structures, studying structural concepts such as weightlessness and the infinite span.  His work extended beyond architecture and engineering to painting and poetry. The bridge design is an homage to him.

The triangulated mesh of the main structural tube is articulated to distinguish between the tensile and compression forces by using simple tie rods for the tensile members. The ties have no compressive capacity and express therefore the tensile zones. The compressive members are in ‘T’ or ‘H’ sections corresponding to the magnitude of forces in them. The section sizes of the members vary as a function of the loading to optimize the steel mass and further express the forces in the system. Mid-span, the lower chords are tensile, while the upper members are compressed. The inverse is true at the support points, where the bending moments are inverted. The shear forces in tubular truss are generally greater at the support points and tending more and more vertical the closer one approaches the supports. The pattern of triangulation of the truss follows this change in direction of forces. The general objective is to find a harmonious geometric composition that expresses the natural passage of forces.


The complexity of the project required the expertise of in international team. Team leaders included Bernard Tschumi and Hugh Dutton, associated architect Veronique Descharrières within BTuA, and Pierluigi Bucci and Pierre Chassagne, engineers at HDA.  Jean-Marie Garnier of the SNCF managed the project for the client and coordinated implementation.

La Roche-sur-Yon, France

Bernard Tschumi and Hugh Dutton

Bernard Tschumi Architects (BTA), joint representative, including general design and preliminary urban studies.

Hugh Dutton Associates (HDA)

Schematic Design, Design Development:  Francoise Akinosho, Ben Edelberg, Kim Starr.  Construction Documents / Site Supervision : Véronique Descharrières, Vincent Prunier, Rémy Cointet, Alice Dufourmontelle

Pierluigi Bucci, Pierre Chassagne, Francesco Cingolani, Maria Angela Corsi, Pietro Demontis, Gaëtan Kolher, Cathy Shortle, Romain Stieltjes, Carla Zaccheddu

City of La Roche-sur-Yon

SNCF  – Engineering Department, Jean-Marie Garnier

Renaudat Centre Constructions

© Christian Richters

November 24, 2010

Railway Footbridge at Roche-sur-Yon

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The project for a footbridge located in Roche-sur-Yon was commissioned as a collaborative work in between HDA Paris, who has a previous experience with the footbridge they did in Turin for the Olympic Village in 2006 and Bernard Tschumi, who recently finished the Acropolis Museum.


The program for the extension of the TGV network in southern  includes a passage through the town of la Roche sur Yon. The town is modernizing the train station and replacing an 1890’s footbridge over the railway tracks. The town is separated by the railway tracks into two parts: the historical central neighborhood, which contains the ‘Pentagon’ planned by Napoleon and it’s contemporary counterpart with its modern facilities (stadium, school and residential zones).The ambition of the town, is not only to create a symbolic link between the two neighborhoods, but equally to celebrate the arrival of the TGV.La Roche sur Yon is the birthplace of Robert le Ricolais, engineer, architect, poet and painter, known for his theoretical research on trellis structures and tensegrity during the 1950’s. This heritage, both intellectual and historical, has inspired the design of the new footbridge by attempting maximum lightness. During the design process therefore HDA combined structural optimization with the architectural concepts by creating a full height filigree lattice tube, that provides not only a support for safety meshes as required by the railway authority, but also maximum structural inertia.The diagonal lattice design recalls the existing old riveted footbridge. At the support points, the stresses are mainly shear, in the predominantly vertical direction, and at mid-span, the stresses become principally bending and the direction tends towards the horizontal. The natures of the forces are highlighted by ‘T’ or ‘H’ section profiles for compression and simple rod ties for those in tension. The transition between supports and mid-spans is also underlined by the presence of vertical circles that recreate links for the shear force transfer. The architectural result is an expression of the natural forces.

It is interesting to consider that the structural optimization process that permits, saving tons of material is not only driven by practical, aesthetic and economic objectives, but also has an ecological dividend.  itself is a recyclable material to begin with. From the initial analyses, where all  sections were identical, the tonnage was reduced considerably using subsequent iterative analyses, and notably by replacing the tension members with thin rods. This also significantly contributed to a delicateness in the architectural quality.

A real scale prototype is now complete and the footbridge construction is in progress and the final delivery is planned during 2009.