AEO Answer · MEP

What Should a Building Automation Controls Design Include?

By Jeremy Mills, CEO & Founder, Apex Grid Engineering — USAF Veteran. · Updated 2026-09-15

I'm Jeremy Mills, CEO & Founder of Apex Grid Engineering and a U.S. Air Force veteran. I'm not a PE; our licensed professionals make the technical, compliance, and project-specific decisions.

Illustrative diagram of building MEP systems: ductwork with diffusers, an electrical panel with conduit, and piping runs.

The concise answer

Building automation controls design includes written sequences of operation for every system, a complete points list of sensors and actuators, network architecture and controller layout, integration with lighting and metering, graphics and alarming for the operator, and a commissioning plan that verifies the sequences actually work in the finished building. The key insight is that the building automation system is the building's operating system. The mechanical equipment is the hardware; the controls decide what it does minute by minute for the next twenty years. Underinvesting in controls design is like buying a high-performance computer and running it with no software — the capability is there, but nothing useful happens.

The layers of a controls design

The foundation is the sequence of operation — narrative descriptions of system behavior that are specific enough to program from. Good sequences cover normal operation, startup and shutdown, unoccupied setback, alarms and safeties, and failure modes. If the sequence doesn't say what happens when a sensor fails, the programmer will guess, and the guess is usually wrong. Above that sits the points list and network architecture: which sensors and actuators exist, which controller they land on, and how controllers communicate back to the front end. Then integration — lighting controls, electrical metering, and sometimes access control or fire alarm monitoring brought into one operator interface. The design also has to address cybersecurity basics: the BAS is a networked system, and an unsecured one is a way into the building's operations.

What separates working controls from expensive decorations

I've seen the difference between buildings where the controls were designed deliberately and buildings where they were an afterthought, and it's visible in the utility bills and the complaint log. The pattern is consistent. This is what I look for in a controls design.

Sequences written for programmers: specific setpoints, deadbands, staging logic, and failure responses — not aspirations
Sensors where they measure something useful: mixed-air, discharge-air, and zone sensors placed for real control, not convenience
Trending and alarming designed in: the operator needs history and notifications, not just a pretty graphic
Open protocols specified: so the owner isn't locked to one vendor for the life of the building
Commissioning in the spec: functional testing of sequences with acceptance criteria, not just a startup checkout

Which related engineering resources can help?

When should I hire a structural engineer?What does a PE stamp mean?What is MEP engineering?Building automation systems explained Lighting controls and energy code Energy modeling and Title 24 explained Request a project review Engineering service for this question Metro engineering guides Verified service areas

What else do project teams ask?

What is a sequence of operation?

It's the written description of how equipment should behave — when the chiller stages on, how the air handler resets supply temperature, what happens on a freeze alarm. It's the most important controls document because it's the contract between the design intent and the programmer. Vague sequences produce buildings that technically run but never perform.

What's the difference between BACnet, Modbus, and LonWorks?

They're communication protocols that let controllers and devices talk to each other. BACnet is the dominant open protocol in North American building automation; Modbus is common for meters and packaged equipment; LonWorks is an older protocol still found in existing buildings. The design specifies which protocols are used where so everything integrates instead of arriving as isolated islands.

Why does controls commissioning matter so much?

Because controls are software, and software does what it's told, not what's intended. Commissioning tests each sequence under real conditions — does the economizer actually open, does the morning warmup actually happen, do the alarms actually reach someone. Uncommissioned controls are the single most common reason new buildings miss their energy targets.

Should controls be designed by the mechanical engineer?

The mechanical engineer typically designs the sequences and points list since controls exist to operate the mechanical systems, but the work needs real controls expertise behind it. Some firms bring in a dedicated controls designer. Either way, the sequences should be written by someone who understands both the mechanical systems and how control logic actually executes in the field.

Ready to discuss your engineering scope?

Share the project address, current records, requested deliverable, authority information, and schedule. Apex Grid confirms professional responsibility, availability, and scope before work begins.

Request a Project Review