Building Automation Scope of Work: Template and Checklist for Commercial GCs

Building automation systems (BAS) — also called building management systems (BMS) or direct digital controls (DDC) — are the most integration-intensive scope in commercial construction. A BAS scope that does not define system architecture, integration requirements, points list, and commissioning responsibilities will result in control systems that cannot communicate with mechanical equipment, energy metering that doesn't feed the right dashboard, and tenant comfort complaints that persist after occupancy. This guide covers the sub-trade requirements, package deliverables, and coordination checkpoints every PM and estimator needs in a building automation scope of work.

BAS scopes must define the complete system hierarchy: field devices, controllers, network infrastructure, and the operator interface — before any equipment is purchased or programmed.

System Architecture and Protocol

• Open protocol vs. proprietary: Specify the required communication protocol — BACnet/IP (ASHRAE 135, most common open standard for commercial BAS), Modbus RTU/TCP, LonWorks, or a proprietary system (Johnson Controls Metasys, Siemens Desigo CC, Honeywell EBI, Schneider EcoStruxure). Open protocol systems (BACnet) allow equipment from multiple vendors and are preferred by owners who want long-term competitive maintenance. Proprietary systems are typically faster to commission but create vendor lock-in.
• System hierarchy: Define the three-tier BAS architecture: (1) Field level — sensors, actuators, and field devices at each piece of equipment; (2) Controller level — unitary controllers (VAV controllers, AHU controllers, FCU controllers) and application-specific controllers; (3) Supervisor level — building controller (BC), operator workstation (OWS), and web-based front end. Specify which tier is in the BAS sub's scope vs. the mechanical or electrical sub's scope.
• Points list: Require the BAS sub to develop and submit a complete points list before programming begins. The points list defines every monitored and controlled point in the system (AI, AO, DI, DO) — including point name, description, engineering units, control range, and alarm setpoints. A complete points list is the foundation of BAS programming and commissioning — projects without an approved points list before programming begins invariably require extensive re-programming at commissioning.

Field Devices and Sensors

• Temperature sensors: Room temperature sensors (setpoint display vs. none, fan speed or mode switch), duct-mounted temperature sensors (averaging element vs. spot), outdoor air temperature sensors (shielded, solar radiation error-corrected). Specify sensor accuracy: ±0.5°F (±0.3°C) for discharge air sensors; ±1°F (±0.5°C) for room sensors is typical commercial specification.
• CO₂ sensors: For demand-controlled ventilation (DCV) per ASHRAE 62.1. Specify accuracy (±50 ppm or better), self-calibration method (ABC — automatic baseline correction), and mounting height (breathing zone, 4–6 ft AFF). CO₂ sensors in rooms with operable windows require field calibration at commissioning.
• VAV box controllers: Specify integrated or stand-alone DDC VAV controllers. Integrated controllers (mounted on the VAV box by the manufacturer) simplify field wiring. Stand-alone controllers (field-mounted, wired to the box) allow greater flexibility for future maintenance. Define which approach is required.
• Damper actuators and control valves: Specify actuator type (spring-return vs. non-spring-return), torque rating matching the damper or valve size, fail-safe position (normally open or normally closed per the mechanical engineer's requirements), and voltage/signal type (24VAC with 2–10VDC modulating signal is standard).
• Energy metering: Specify electrical sub-metering (kWh, kW, PF per tenant or system), BTU metering for chilled water and heating hot water (flow meter + supply/return temperature sensors), and natural gas sub-metering. Define which meters integrate into the BAS vs. which feed a separate energy management platform.

BAS Network Infrastructure

• BACnet/IP network: typically runs on the building's IT network or a dedicated BAS VLAN. Define whether the BAS network uses the owner's IT infrastructure or a dedicated BAS network. If using the owner's network, require the BAS sub to provide network requirements (IP address allocation, VLAN configuration, firewall rules) to the owner's IT team at least 60 days before commissioning.
• BACnet MS/TP (master-slave/token-passing): for field-level device networks connecting VAV controllers on a trunk line. Specify maximum devices per MS/TP segment, cable type (22 AWG shielded twisted pair), and termination resistor requirements.
• Cybersecurity: specify that the BAS system must comply with the owner's IT security requirements. BAS systems connected to the internet require VPN access, encrypted communications, and role-based access control. Define these requirements in the scope before the BAS sub finalizes system architecture.

Tip for PMs: The most common BAS scope gap is the integration interface to non-BAS systems — the elevator controller, the fire alarm panel, the lighting control system, and the electrical sub-metering system. Each of these requires a specific integration protocol (BACnet gateway, Modbus gateway, or dry contact) and a defined data exchange specification. These interfaces are rarely included in a base BAS bid unless explicitly called out in the scope.

BAS submittals are highly technical and require significant lead time. The programming and commissioning schedule must be built into the construction schedule from the project start.

Required Submittals

• System architecture drawing: showing system topology, controller locations, network connections, and integration points with mechanical equipment and other building systems
• Points list: complete AI/AO/DI/DO listing with engineering units, ranges, and alarm setpoints — for owner/engineer approval before programming
• Control sequences of operation (SOO): written sequence for every mechanical system — AHU, chiller, boiler, cooling tower, VAV system, fan coil unit — reviewed and approved by the mechanical engineer before programming
• Product data sheets for all field devices, controllers, and operator interface software
• BAS network drawing showing IP addresses, VLAN assignments, and integration gateway locations
• Graphic screen submittals: floor-by-floor and system-level screen graphics for owner review before commissioning

Commissioning and Training

• Specify that the BAS sub is responsible for functional testing of all controlled points and sequences before the commissioning agent (CxA) independent verification. Require a completed BAS contractor commissioning report as a deliverable.
• Owner training: specify a minimum number of training sessions (typically 2 half-day sessions for facility management staff) covering system operation, alarms, schedules, setpoint adjustments, and trend logging. Require training materials in electronic format.
• Warranty and ongoing maintenance: define the BAS warranty period (minimum 1 year parts and labor) and the ongoing support arrangement. BAS systems with unresolved commissioning issues at handover frequently generate expensive service calls in the first year of operation.

Best Practices from Leading GCs

• Hold a BAS coordination meeting with the mechanical sub, electrical sub, and BAS sub before rough-in begins. Define who provides and installs all field device conduit and wiring — this is a recurring grey zone between the BAS sub (who provides the devices) and the electrical sub (who provides conduit and low-voltage wiring in some contracts).
• Require the BAS sub to participate in the mechanical commissioning process as an active participant, not just an observer. The BAS sub must trend all relevant points during mechanical commissioning — static pressure, supply air temperature, valve position — so that control loop performance can be verified against the sequence of operations.
• Define a BAS pre-commissioning checklist: before the CxA arrives for functional testing, require the BAS sub to demonstrate that all points are live, all actuators respond to manual commands, and all graphic screens are populated with live data.

BAS is the integration layer for the entire mechanical and electrical system. Early and sustained coordination with the mechanical sub and the owner's IT team is essential.

Mechanical Sub Coordination

• The mechanical sub's equipment submittals must be reviewed by the BAS sub before mechanical equipment is ordered. VAV boxes, AHUs, chillers, boilers, and cooling towers all have specific BAS integration requirements (BACnet MSTP, Modbus, or analog I/O) that must be compatible with the specified BAS system. Discovering a compatibility issue after equipment delivery is one of the most expensive BAS coordination failures.
• Coordinate all control panel locations with the mechanical sub: BAS control panels must be accessible for maintenance, adjacent to the equipment they control, and located where conduit home-runs are practical. Panel locations shown only on the BAS drawing (not on the mechanical drawing) are routinely installed in conflict with equipment access clearances.

Owner's IT Team Coordination

• IP address allocation and VLAN configuration: require the BAS sub to submit network requirements 60 days before network installation. The owner's IT team typically controls IP address assignment and firewall rules — late submittals delay BAS network commissioning.
• Remote access: confirm with the owner how remote access to the BAS will be provided — VPN, cloud-hosted operator interface, or site-hosted server. Define who hosts, maintains, and secures the remote access system.

Pre-Commissioning Coordination Checklist

• Points list submitted, reviewed, and approved
• Control sequences of operation approved by mechanical engineer
• Mechanical equipment submittals reviewed by BAS sub for integration compatibility
• BAS network drawing submitted to owner's IT team — IP address and VLAN allocation confirmed
• All field devices installed and wired — points checked live before commissioning agent arrives
• Graphic screens populated and reviewed
• Integration interfaces to non-BAS systems (fire alarm, elevator, lighting) tested
• BAS contractor commissioning report submitted before CxA testing begins

Tip for Estimators: When reviewing a BAS bid, verify that the following are included: points list development, sequences of operation programming, graphic screen development, commissioning participation, and owner training. BAS bids that list only "supply and install DDC controls" without programming, commissioning, and training are typically missing 30–50% of the total BAS contract value.