Requested toilet-replacement simulation rescues bid with installation coefficient 0.2 against price challenge
Imtech bid installation coefficients of 0.2 to 0.5 for sanitary works in Brussels — far below competitors — compensating with a higher materials coefficient; the City asked for a simulation on concrete line items and accepted the justification, and the Council of State follows: in a unit-price contract, what counts is the combination of elements, not one isolated low number.
What happened?
The City of Brussels published on 22 March 2022 a contract for sanitary works — replacement, extension, maintenance — on City and police-zone buildings (lot I) and on municipal real-estate buildings (lot II). A unit-price contract for 3 years, open procedure, awarded on lowest price coefficient. The specifications divide the work into nine chapters; per chapter the bidder gives a coefficient X (materials) and Y (installation) applied to the unit prices in the schedule. Total offer = sum of those coefficients weighted by the standard ratios between chapters. Three companies bid: Établissements Karl Bouvé, Imtech Belgium and Axo. Imtech wins both lots with global coefficients 72.00 (lot I) and 75.28 (lot II) — about 23% cheaper than Bouvé and 60% cheaper than Axo. In price scrutiny, four Y-coefficients of Imtech stand out as apparently abnormally low: 0.5 for chapter 1, 0.2 for chapter 6, 0.2 for chapter 7, 0.3 for chapter 8. The City requested justification on 2 August 2022 plus a 'simulation' of two concrete tasks: replacing a free-standing toilet with a wall-hung one, and replacing 15 cold-water taps. Imtech replied on 11 August with Excel sheets per chapter detailing material purchase price, mark-up, direct and indirect costs, plus labour. Conclusion: Imtech compensates the low Y-coefficients with higher X-coefficients on materials, gets large discounts from suppliers, and keeps a 'correct margin' per item. On 9 March 2023, the College of mayor and aldermen awarded to Imtech. Bouvé requested suspension on four grounds: inadequate reasoning of the price acceptance, unauthorised simulation outside the schedule quantities, missing presumed quantities in a 'framework agreement', and absence of the mayor at the decision. The President rejected all four. The motivation explains why the short installation times are credible (materials compensation, supplier discounts, scale advantages for repeat work per site) — sufficient. A simulation outside schedule quantities is lawful as long as it does not demonstrably favour one bidder. It is not a framework agreement but a unit-price contract — no obligation to give presumed quantities. And Bouvé itself bid identical coefficients for chapters 7 and 8 as in the previous 2018 contract — hard to maintain those coefficients are now suddenly unrealistic.
Why does this matter?
In unit-price contracts (unit prices × actually executed quantities), the temptation is great to bid aggressively on one component — say installation — and compensate on materials. Competitors who see this immediately think 'abnormally low', but the Council teaches that the contracting authority may look further than one coefficient: the interplay between X and Y, purchase discounts, volume per chapter and the history of previous contracts can together yield a 'reasonably realistic' price. For those who use such compensation themselves: document it thoroughly and be ready to deliver a simulation that makes the logic concrete.
The lesson
When you bid with notably low coefficients on one component of a unit-price contract, you must be able to draw out the compensation logic behind your price structure in advance. Expect the contracting authority to ask for justification — and consider the possibility of a simulation request on concrete line items. As a competitor, by contrast, you have almost no chance as long as the award report explains why the combination of X- and Y-coefficients yields a credible price overall: you must prove the contracting authority manifestly misjudged, not that one component was low.
Ask yourself
In a unit-price contract: does the award report contain an analysis where coefficients on materials, installation and hourly rates are placed side by side, with reference to subcontractor or supplier prices or historical data? Or does the report only state that 'the bidder explained that they compensate'? In the latter case, the award is vulnerable — request additional reasoning before the authority finalizes.
About this database
The Council of State (Raad van State / Conseil d'État) is Belgium's supreme administrative court. In disputes over public procurement — from contract awards to tenderer exclusions — the Council of State is the final arbiter. The rulings in this database are summarised by TenderWolf in plain language, with practical lessons for tenderers and contracting authorities. View all rulings →