75% of project cost is committed by the time concept design closes. Not spent — committed. The decisions made earliest are the ones that cost the most to change. By the time most teams begin to manage risk, the largest risks are already locked in.
This is not a procurement failure. It is a validation failure — and it happens at the stage most organisations treat as too early for process.
of project cost is committed during concept design. Not after specification. Not at tender. At the point when the team is still thinking in principles and treating every decision as provisional.
The standard project cost curve shows expenditure climbing through design, procurement, and construction. What it obscures is that cost commitment — the decisions that will determine what gets spent — follows a completely different curve.
Patrick MacLeamy’s analysis of the design process demonstrated this in 2004 and the insight has held: the ability to influence cost and performance is highest at the start of a project, when almost nothing has been spent. As decisions accumulate and commitments are made, the window for cost-effective change closes rapidly.
By the time concept design closes, the structural approach, systems strategy, spatial configuration, and key technical assumptions are largely set. Each of those choices carries a cost implication that will travel through every subsequent stage. Changing any one of them after the fact costs multiples of what it would have cost to get it right at the beginning.
Research into design change across project development phases consistently shows that the cost of making a change increases by an order of magnitude as the project progresses. A decision revisited during concept design costs roughly one unit of effort. The same decision revisited during detailed design costs ten times that. Revisited during construction, it costs a hundred times more — and still may not fully recover the original intent.
This multiplier is not theoretical. It shows up as rework hours, redesign cycles, procurement delays, value engineering that removes what was valuable, and planning conditions that reflect a concept assembled without adequate scrutiny.
The implication is direct: the return on validation at concept stage is not proportional to what validation costs. It is proportional to the cost of every downstream correction it prevents. For most AEC projects, that ratio is not close — early validation is almost always the cheaper path.
There is a simpler way to frame this. The brief set at concept design — the assumptions built in, the options closed off, the constraints accepted without scrutiny — is not a starting point. It is an inheritance. Every team that touches the project after concept stage works within the envelope it defines.
If that envelope was set without structured validation, the downstream teams inherit its blind spots. They optimise within constraints they did not choose and may not fully understand. They deliver a project that reflects the quality of thinking at its earliest stage — not the quality of the work that followed.
Structured validation at concept design does not slow this process. It narrows the gap between what the brief intends and what the project actually delivers — and it does so at the point where narrowing that gap is cheapest.
The Innovation Validation Workshop is designed for exactly this stage. It is a half-day structured session that stress-tests the assumptions behind a live project before decisions lock in. It surfaces what the team believes to be true, what is actually evidenced, and where the gaps are — while there is still room to close them.
The output is practical: a ranked risk register, a clear view of where validation is most needed, and a defined next step. Not a report that sits on a shelf — a set of decisions that get made earlier, with better information, at a fraction of the cost they would carry if left to surface downstream.
If the pattern repeats across projects — if concept design risk is systemic rather than project-specific — the Advisory Partnership addresses it at the practice level.