The independent counter-estimate

It is a second estimate, prepared independently, from the same drawings, the same brief and the same price date as the estimate being checked. The author does not reuse the architect's figures: they measure the quantities themselves and apply their own prices, then compare.

It differs from a simple review. A review checks the consistency of an existing document (totals, missing items, units). A counter-estimate rebuilds the figure. It costs more, but only a counter-estimate can say whether the original estimate is cautious, realistic or optimistic.

It also differs from tendering. Asking contractors for prices before the documents are complete produces figures with no commitment and often no common basis; in a public contract, such figures do not provide a reliable basis for the devis (estimate).

A counter-estimate only makes sense if its answer can still change a decision.

Moment	Question it answers	Decision it informs
End of preliminary design	does the design fit within the budget in the agreement?	adjust the design or the brief before detailed design
Before tendering	are the documents complete and is the devis realistic?	launch, correct or decide trade-offs before prices are fixed
Before signing a major private contract	is the selected tender in line with the works?	negotiate, reduce the scope or sign with full knowledge
Before a municipal council resolution	is the estimate put to the council reliable?	approve the detailed final design or have it revised

For a municipality, the last case is the most sensitive. The municipal council approves the detailed final design (implementing Grand-Ducal Regulation of 8 April 2018, art. 146), and any subsequent significant departure must be approved by the council and the supervisory authority (art. 147). A weak estimate approved by the council means having to go back to it later.

The author must have the competence to price and no interest in the outcome. In practice, this means an ingénieur-conseil (consulting engineer), a cost consultant (économiste de la construction) or an engineering consultancy. For the consulting engineer, independent practice is incompatible with the profession of contractor (Grand-Ducal Regulation of 17 June 1992, art. 4 and 5).

No specific legal status for the cost consultant has been identified in the texts read. The cost consultant is presented by the assignment, as defined in the contract. The client therefore checks what guarantees independence: no link with the contractors invited to tender or with the design team, comparable references, a described method. The respective roles of the advisers on the client's side are presented in the article on the architect, the consulting engineer, the cost consultant and the project manager.

The comparison covers five elements, always in the same order. The first two are settled before comparing a single price:

• The scope. Do the two estimates cover the same thing: works only or total cost, external works, demolition, utility connections, VAT? A difference in scope is not a difference in price.
• The price date. Two estimates at different dates can only be compared once brought to the same date. The public sources useful for situating prices and their movement are presented in the article on official sources.
• The quantities. This is often where most of the gap lies. A different measurement method (gross or net areas, deductions for openings, linear runs) is enough to make two totals diverge.
• The unit rates. With equal quantities, the price gap is read item by item. A gap concentrated on a few major items is more informative than a diffuse one.
• The missing items. This is the most frequent contribution of a counter-estimate: an item absent from the original estimate is not seen by rereading, it is seen by rebuilding.

An item-by-item structure makes all of this easier: it is described in the article on building an item-by-item estimate. At the tender documents stage, the comparison is made on the priced schedule, following the method in the article on checking a schedule before tendering.

Gap found	Likely reading	Next step
Gap concentrated on quantities	measurement method or drawings read differently	compare the two sets of measurements on the items concerned
Gap concentrated on a few unit rates	different price or technical assumption	ask the architect to justify those prices
Items missing from one of the two estimates	omission or poorly defined scope	complete the estimate and check the tender documents
Diffuse gap, every item slightly dearer	different general price level or price date	check the date, then each author's price reference
Small gap	the two estimates converge	the decision rests on the budget, not on the estimate

A fictitious example, to illustrate the reading. The architect's estimate amounts to €1,800,000 excluding VAT and the counter-estimate to €2,050,000 excluding VAT, at the same price date: the gap is €250,000. Broken down, it consists of €150,000 in quantities (facades measured as developed surface area in the counter-estimate), €60,000 in items missing from the original estimate (utility connections and external works) and €40,000 in unit rates on the structural works. Most of the gap therefore does not come from prices: the discussion with the architect focuses first on the facade measurements and on the scope.

Convergence is not certainty. Two close estimates prepared from incomplete drawings share the same unknowns. They show that the figure is consistent with the design as described, not that the tenders will confirm it.

The counter-estimate can serve as the basis for the contracting authority's devis. The devis is then subject to the same confidentiality rule: "It is prohibited to make known to tenderers the devis that the contracting authorities have drawn up for the execution of the entire undertaking or of certain parts of the undertaking only" (implementing Grand-Ducal Regulation, art. 45 (5), unofficial translation). For contracts above the European thresholds, only the total estimated value may appear in the notice.

After opening, the examination of the tenders may draw on experts. The regulation provides that tenders are examined in particular "as to the soundness of the prices and the accuracy of the calculations", with the possibility of calling on experts (art. 80 (1)). A detailed counter-estimate then provides a framework for reading the prices submitted, item by item.

It does not allow negotiation. In an open or restricted procedure, the contracting authority may not come to an arrangement with the tenderers to change their prices after opening (art. 85). Its usefulness lies before that point, in the quality of the devis and the tender documents.

The quality of the answer depends on the precision of the request. Give the third party exactly the documents behind the estimate being checked (drawings, brief, specification, any priced schedule), with their revision index. Set the price date to be used and the scope (works only or total cost, excluding VAT). Ask for an output by items aligned with those of the original estimate, with the price assumptions and the measurement method. Allow a timescale compatible with the decision to be made.

Informing the architect is not a sign of mistrust. The counter-estimate is more useful if the two authors can then compare their figures on the items where they differ.

It does not replace the architect's estimate, nor the architect's responsibility. The architect remains bound to submit designs within the limits of the brief and the budget (1992 regulation, art. 9); the counter-estimate documents a gap, it does not transfer that obligation to the third party.

It does not decide. If it confirms that the estimate exceeds the budget, the next step is the trade-off described in the article on an estimate that exceeds the budget before tendering. If it shows that the estimate is overstated, that does not in itself justify reducing the devis without grounds.