Design economics and cost planning questions
Cost planning is questioned as a process over time, not a single number. The assessor wants to follow one project's cost from the first order-of-magnitude estimate through to the tender return, and to hear what you did each time the design moved. Have one project ready to walk through end to end.
Design economics & cost planning
Manage the cost of design development from feasibility to design completion; advise on cost, time, quality and buildability, on market factors and trends, and on accuracy and risk. Core to Level 3 in a consulting environment.
What the assessor is listening for
- That your estimates are traceable: source data, adjustments made, and the reasoning for each.
- That you can explain what you adjusted for and why (location, time, specification, market conditions), rather than quoting a rate.
- That the plan was maintained: reconciled at each stage, with movements explained.
- That you gave advice when the design and the budget diverged, and did so early.
Level 1
Knowledge & understanding - you can explain the principle.
- How does an estimate change as a design develops?A strong answer covers: The progression from a functional or area-based estimate through elemental cost planning to a measured, priced document, and what happens to the accuracy and the contingency along the way.
- Where does your cost data come from, and what do you do to it before you use it?A strong answer covers: The sources you actually use, then the adjustments: time, location, specification, quantity and market conditions. The point that unadjusted historic data is not evidence.
Level 2
Application - you have done it yourself and can describe how.
- Talk me through a cost plan you produced.A strong answer covers: The stage, the information available, how the plan was structured, the assumptions and exclusions recorded, the risk allowance and how it was arrived at, and what you told the client it meant.
- How do you handle risk and contingency in an estimate?A strong answer covers: How the allowance was built (a considered assessment against identified risks rather than a flat percentage), where it sits in the plan so it stays visible, and how it is drawn down as risks close out.
- The design has moved. How do you report the change in cost?A strong answer covers: A reconciliation from the last reported figure to this one, movement by movement, separating design change, market movement and correction. Then what you asked the client to decide.
Level 3
Reasoned advice & depth of judgement - you have advised others and can justify decisions and trade-offs.
- The scheme is over budget. What do you advise?A strong answer covers: Options with consequences attached: specification, scope, phasing, programme, or more money. What each buys and costs, which you recommend, and the decision the client actually has to make.
- How do you advise on value rather than just cost?A strong answer covers: Cost against what the client gets for it: function, life cycle and operating cost, and the trade-offs. A worked instance where the cheapest option was not the one you recommended.
- How does the sustainability of a design affect the advice you give on cost?A strong answer covers: Capital against whole-life cost, the client's own targets and obligations, what is well evidenced and what is not, and how you present a case where the capital cost is higher.
How candidates lose this one
Presenting a rate with no provenance. The follow-up is always where it came from and what you did to it.
Reporting a cost plan without a reconciliation. A number that moved with no explanation is the thing assessors pull on.
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