Project explores faster BIM data transfer between stakeholders

A government-backed project to create a new industry standard for live streaming design changes in BIM is looking to apply the technology to other areas, such as digital twins, post-occupancy evaluations and decentralised data management.

The AEC Delta Mobility project received a £1m grant from Innovate UK to develop tools and processes to engage manufacturers in the early stages of design and increase the productivity of construction projects by over 15%.

The consortium, which includes Buro Happold, 3D Repo, UCL Bartlett School of Construction & Project Management, and Speckle Works, has developed an open-source platform that can rapidly communicate design changes, called deltas, between BIM project stakeholders, removing the need to exchange large and cumbersome 3D models.

The project’s 18-month first phase is now close to completion and the team is keen to hear from collaborators for a potential second phase of development.

Dr Al Fisher, head of computational development at Buro Happold, told BIM+: “More accurate digital twins of buildings are needed for post occupancy analysis and the ability to stream up-to-date information on how buildings are being used could be one area of research. Deltas utilise a decentralised data sharing model, which could have big implications for the security, ownership and management of data, this is another possible area of research.”

BIM platforms are currently held back by a relatively inefficient method of sharing files that requires designers, consultants and specialists to share entire 3D models with large payloads. This can make design coordination and tracking changes onerous and time consuming.

AEC Delta Mobility’s system communicates only the parts of the file that are modified or removed, which results, on average, in a five-fold increase in the speed of information transfer and a greater capacity for design optioneering.

Fisher adds: “Faster file sharing means people are freer to share several different design options in parallel. For example, an engineer can share five different options for column positions efficiently, without having to share the entire model five times.”

Decentralised collaboration

The technology functions in a similar way to platforms used for decentralised collaboration in the software development industry, which identify only the specific lines of code that have been altered in a document.

Two versions of a BIM model – the state before any changes and the state after – are examined and a ‘diff’ file is created to record the differences, which forms the basis of a delta.

The AEC Delta server tracks all revisions, for example the removal, addition or modification of columns or facade panels, which are highlighted in different colours in the model.

The new data transfer specification could become a useful tool to track authorship, says Fisher, and audit changes on large complex projects involving numerous contributors.

In initial tests of the system, Grasshopper design software was linked via live adapters to Speckle Systems, an open source platform for hosting and streaming BIM models, and 3D Repo, a cloud-based BIM viewer and collaboration platform. When the number of floors of a building were changed in Grasshopper, the data was live streamed to Speckle Systems and 3D Repo to reflect the changes.

Deltas offer the opportunity to communicate design decision making, rather than end results in an entire BIM model, says Fisher: “Currently there’s a danger that everyone is inputting worst case, conservative values, so you end up with an over-conservative model. Deltas make it possible to stream richer, smaller amounts of information, which enables a potentially richer design conversation.”

He adds: “It’s about being able to share the logic of design decisions and have a conversation about, for example, whether you need to increase a particular parameter by 20% rather than 50% and so find a genuine optimum that satisfies multiple parties.”

With technical development now complete, the intention is to test the system on live construction projects in the UK with project partners Buro Happold, Rhomberg, HOK and Atkins.

Image: The AEC Delta server tracks all revisions, which are highlighted in different colours in the model (Image: Speckle Systems

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