Comparing BMS tender returns: a guide for main contractors

When you receive three BMS quotes with three different point counts, how do you know which one is right? Returns on the same specification routinely differ by 40 per cent or more, and it is rarely because one contractor is greedy. It is because BMS estimation involves hundreds of interpretation decisions, and each return made them differently.

The three sources of variation

Scope interpretation

The biggest source. Does the VRF system need individual indoor unit monitoring or just a gateway? Are the meters BMS scope or the metering contractor's? Is the domestic hot water plant monitored or left alone? Each decision swings the price by thousands, and the specification usually supports more than one reading.

Points methodology

Even with agreed scope, estimators count differently. Some count duty and standby pumps separately, others as a set. One contractor's AHU template carries 25 points, another's 35. Neither is wrong; they reflect different delivery habits. But the difference is invisible in a lump sum.

Rates

Hardware, labour and margin differ between contractors, but less than people assume. Two returns far apart are usually two different points schedules, not two different margins.

How to compare returns properly

Ask every bidder for their points schedule, not just a total, then:

• Compare equipment lists side by side. An item in one return and missing from another is a scope interpretation difference. Make the bidders name it.
• Compare point totals by type. AI, DI, AO, DO and high-level counts reveal methodology. A return heavy on high-level points is quoting network integration where another is quoting wiring, and the delivered systems will differ.
• Read the exclusions before the price. The cheapest return usually excludes the most. Provisional sums and "by others" lines are where the gap between quotes gets repaid later, with interest.
• Check the terminal unit counts. FCUs, VAVs and similar repeated items are where counting errors compound. If two returns disagree about how many fan coils the building has, at least one of them has miscounted, and it is worth knowing which before you sign.

The value of a baseline

All of this is easier with an independent equipment list and points schedule in hand before returns arrive. Then comparison stops being triangulation between three opinions and becomes measurement against a benchmark: which return missed the roof plantroom, which assumed a gateway, which counted 80 fan coils in a building that has 62.

This is what Tenderfly provides for main contractors and M&E contractors: an independent BMS scope baseline generated from the tender documents themselves, with every item traceable to the page it came from. Not a fourth quote; a way of judging the three you have.