How to Design a BMS System?

The Architect's Rule

A house is never built before it is drawn. Every wall, every door, every pipe is on paper first. Wrong on paper costs nothing. Wrong in concrete costs everything.

BMS design works the same way.

The 8 Steps:

Step 1 — UNDERSTAND THE BUILDING
  Type: office / hospital / mall / pharma / hotel / data centre
  Size: floors, gross area per floor
  Systems: HVAC only? Or HVAC + lighting + energy + security?
  Standard: ASHRAE? LEED? 21 CFR Part 11? Local codes?
Step 2 — SURVEY AND LIST ALL EQUIPMENT
  Walk every floor with MEP drawings
  Count every AHU, FCU, exhaust fan, chiller
  Note make and model of major equipment
  Identify third-party systems needing integration
  Missing one equipment here = missing wiring = commissioning problem
Step 3 — POINTS SCHEDULE (IO LIST)
  For every equipment — decide what to monitor and control
  AHU-01: 10 points
  FCU-01: 3–4 points
  Large building: 500–2000+ BMS points total
Step 4 — CONTROLLER SELECTION AND DISTRIBUTION
  Group nearby equipment to one controller
  Floor 3 AHU + 12 FCUs on Floor 3 = one controller panel
  Select controller size based on point count
Step 5 — NETWORK DESIGN
  BACnet IP backbone or MS/TP or combination
  IP addressing plan for all controllers
  Network redundancy for critical buildings
Step 6 — PANEL DESIGN
  Controller, terminal blocks, power supply, surge protection
  Panel location: near the equipment it serves
Step 7 — SEQUENCE OF OPERATIONS
  For every system — write control logic in plain English
  AHU, FCU, chiller, exhaust fans, energy metering
  This document is given to programmer
  Programmer converts to FBD
Step 8 — DESIGN REVIEW AND APPROVAL
  Issue to client, MEP contractor, electrical contractor, IT team
  Get written approval before procurement
  Changes after approval = cost and delay