What is a BMS points schedule and why does it take so long

An explainer for anyone outside the BMS industry who needs to understand what a points schedule is, why it determines the price, and why producing one manually takes days per tender. Written for M&E contractors, main contractors and developers who receive BMS quotes without full visibility of what sits behind them.

What a points schedule is

A building management system controls and monitors a building's mechanical and electrical plant. Every connection between the BMS and a piece of equipment is a point, and the points schedule is the complete list of them. There are five types:

• AI (analogue input): a continuous measurement. Temperatures, pressures, flow rates.
• DI (digital input): an on-off status. Pump running, fan tripped, filter dirty.
• AO (analogue output): a continuous command. Valve position, fan speed.
• DO (digital output): an on-off command. Enable the pump, start the fan.
• HL (high level): a software integration over BACnet or Modbus, where one network connection carries many readings. VRF systems, chillers, meters.

A worked example

A single fan coil unit, controlled directly, might carry: a space temperature sensor (AI), a fan enable (DO), a fan status (DI), heating and cooling valve actuators (2 AO), and a condensate alarm (DI). Six points for one small unit. Now multiply: an office floor might have thirty fan coils, and the building has plantrooms, air handling units, pumps, meters and a chiller on top. A small school lands around a few hundred points; a large hospital can pass ten thousand.

Why it determines the price

Each category of BMS cost keys directly off the schedule. Hardwired points drive panel sizes, IO modules, cabling and field devices. Every point, wired or networked, drives software configuration and commissioning time, because each one must be set up and then proven end to end. High-level points drive integration work. When a BMS quote is wrong, the cause is almost always in the points, not the rates.

Why it takes days

Producing the schedule means reading everything: the mechanical specification, the equipment schedules, the schematics, the plans. Every controlled item must be found, including the ones that only exist as a sentence of prose. Then each item needs the right set of points, which depends on its type, its control strategy and what the specification actually asks for, including the judgement call of whether it is wired directly or integrated over the network.

That is careful, skilled, repetitive work across hundreds of pages, and it is why it consumes two or three days of a senior engineer per tender. It is also why the schedule, not the pricing, is where tenders are won, lost and occasionally regretted.