Digital twins can tell us what is being built. But what about the commercial story unfolding around it? RLB proposes the Commercial Twin: a new way to connect cost, program, procurement, risk and decisions as a project evolves.
5D building information modelling (BIM) has changed the speed of cost advice.
When a design model changes, quantities can be updated quickly, allowing the quantity surveyor to revise the estimate and advise the client on projected final cost. Its strength lies in connecting design, quantities and cost.
But a project’s commercial position is shaped by more than a design model.
Final cost also depends on when work will be delivered, prices secured from the market and how much of the forecast is based on confirmed information, rather than assumptions.
Quantity surveyors already manage these variables across separate cost plans, programs, procurement schedules and change records. The opportunity is to connect them so the commercial consequences of new information can be understood across the project.
That is the purpose of the Commercial Twin.
“Commercial information is not simply a number. It is a value with a basis, a status and a history.”
What is a Commercial Twin?
A Commercial Twin, in theory, is a connected digital representation of a project’s evolving commercial position. It applies the idea of a digital twin to the commercial side of a project, not just the physical asset.
Every cost has a lifecycle. An early allowance may begin as a benchmark because the design is incomplete. It becomes a measured estimate, is tested through tendering, forms an accepted commitment and eventually becomes an actual cost. The value may relate to the same work throughout, but its meaning changes as better evidence becomes available.
Commercial information is not simply a number. It is a value with a basis, a status and a history.
The Commercial Twin preserves that history instead of replacing one figure with another. Instead of presenting the current forecast as an isolated total, it shows what changed, why it changed and how the project arrived there.
From cost model to commercial model
A design model is organised around physical components. Commercial management follows a different structure: work is estimated, procured, contracted and controlled.
This difference matters. One trade contract may cover hundreds of modelled objects, while preliminaries, escalation or delay may not belong to any single design object. Commercial information, therefore, needs its own structure.
In this scenario, the Commercial Twin connects to 5D BIM where modelled scope and quantities inform cost, while also drawing on program, procurement, commitments, actual costs, changes and risks. It doesn’t replace the design model. It places that design information within the commercial reality of how the project is bought, delivered and controlled.
How certain is the forecast?
A conventional forecast may present an agreed commitment and an early allowance as equally dependable, because both appear as single values in the total. The Commercial Twin would show the difference between them.
Each amount could be assessed against criteria such as design maturity, the source of the price and whether it has been tendered, approved or committed. The forecast could show an expected outcome together with a range that narrows as more information is confirmed.
Contingency could remain linked to the uncertainty for which it was provided, making it clearer when an allowance can genuinely be released and when exposure still exists. The client would not only see the expected final cost, but also how much confidence can reasonably be placed in it.
Testing decisions before they become costs
Perhaps the greatest potential lies in comparing different paths while a decision is still open.
A cost report explains the approved position. A Commercial Twin could preserve that position while testing alternatives alongside it: proceeding with the current design or developing an alternative; procuring now or waiting for more information; accelerating the program or retaining the existing sequence.
The client could see how each option affects final cost, expenditure timing and risk without changing the formal forecast until a decision is approved.
The purpose is not to predict the future with certainty, but to make the likely consequences clearer before the opportunity to choose has passed.
Cost advice then becomes more than a record of the project’s position; it helps the client decide what that position should become.
The evolving role of the quantity surveyor
The Commercial Twin would not diminish the quantity surveyor’s role. If anything, it exposes the importance of professional judgement.
A model may show that a value or program date has changed. But the quantity surveyor must determine what that change means commercially – whether tenders are comparable, a program revision creates a cost consequence and a risk justifies changing the forecast.
Once that assessment is approved, its effect could be carried through the projected final cost, cash flow, contingency and reporting outputs. Less time would be spent repeating updates across disconnected records; more time could be spent testing new evidence, exploring options and advising clients.
Over time, the history held within the Commercial Twin could strengthen benchmarks by comparing early allowances with tendered, committed and actual costs.
Making the Commercial Twin credible
The Commercial Twin does not require one enormous software platform. It requires existing project information to be connected reliably.
The same piece of work must be recognisable whether it appears in the design, cost plan, program, tender package, change record or contract. Only approved information should update the formal forecast, while developing information and alternative scenarios remain separate.
The challenge is not to make every number change instantly. It is to ensure that the latest reliable information is reflected when a decision must be made.
The Commercial Twin is, therefore, not another BIM dimension or a digital version of the cost report. It represents the commercial reasoning surrounding the asset: how values develop, how dependable the forecast is and how decisions may change the outcome.
A digital twin can show what is being built. A Commercial Twin can show what the project is becoming.
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