1 Scope
NOTE This specification covers the materials, configuration, programming, integration, commissioning, and cybersecurity hardening of the building automation system (BAS), a networked direct digital control system for HVAC and ancillary mechanical building systems. (1.1)
NOTE The system addressed in this standard is organized in four layers: a server / management layer that hosts the operator interface, historian, and database; a supervisory layer of network controllers that perform integration, scheduling, alarming, and global control logic; a field controller layer of application-specific and programmable controllers that execute the sequence of operations at each piece of mechanical equipment; and a field bus and I/O layer of sensors, actuators, and equipment integration points. (1.2)
1.3 The default open communication protocol for this standard shall be BACnet, as defined by ANSI/ASHRAE Standard 135 and ISO 16484-5.
1.4 BACnet shall be required at every interface where multi-vendor interoperability is needed.
1.5 Modbus (RTU and TCP) is permitted as a secondary protocol for integrating specific equipment that lacks a native BACnet interface.
1.6 Proprietary protocols are permitted only within a single manufacturer's product family below a BACnet boundary.
1.7 The system shall be designed so that the operator interface, the supervisory layer, and all primary equipment integration are accessible via BACnet objects regardless of the field bus protocol used inside any individual subsystem.
1.8 Scope Boundaries
NOTE This standard covers cybersecurity provisions that constitute the minimum baseline for operational technology in a commercial building — network segregation from the production data network, account management, patching discipline, and audit logging — derived from the practices of NIST SP 800-82. (1.8.1)
NOTE Sequences of operation are established on the contract drawings and in the equipment standards; this standard governs the platform that executes those sequences. (1.8.2)
1.8.4 Power supply to BAS panels shall be Class 2 unless otherwise indicated and shall comply with NFPA 70 Article 725.
1.8.5 Interface to the fire alarm system for fan and damper command shall comply with NFPA 72 and is addressed here only at the interface; the fire alarm system itself is governed by Fire Alarm Systems. 2 Referenced Standards
2.1 Equipment, materials, and installation shall comply with the latest adopted edition of the following standards.
2.2 Where the contract documents, the adopted building code, or a referenced standard conflict, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.
| Standard |
Title |
| ANSI/ASHRAE 135 |
A Data Communication Protocol for Building Automation and Control Networks (BACnet) |
| ISO 16484-1 |
Building Automation and Control Systems (BACS) — Project Specification and Implementation |
| ISO 16484-2 |
Building Automation and Control Systems — Hardware |
| ISO 16484-3 |
Building Automation and Control Systems — Functions |
| ISO 16484-5 |
Building Automation and Control Systems — Data Communication Protocol |
| ISO 16484-6 |
Building Automation and Control Systems — Data Communication Conformance Testing |
| ASHRAE Guideline 13 |
Specifying Direct Digital Control Systems |
| ASHRAE Guideline 36 |
High-Performance Sequences of Operation for HVAC Systems |
| ANSI/ASHRAE/IES 90.1 |
Energy Standard for Buildings Except Low-Rise Residential Buildings |
| ANSI/ASHRAE 62.1 |
Ventilation and Acceptable Indoor Air Quality (includes Demand-Controlled Ventilation provisions) |
| ANSI/ASHRAE 188 |
Legionellosis: Risk Management for Building Water Systems |
| NIST SP 800-82 |
Guide to Operational Technology (OT) Security |
| NFPA 70 |
National Electrical Code (Articles 725 — Class 2 control circuits, 800 — Communications) |
| NFPA 72 |
National Fire Alarm and Signaling Code (interface to fire alarm) |
| NFPA 90A |
Standard for the Installation of Air-Conditioning and Ventilating Systems |
| UL 916 |
Energy Management Equipment |
| UL 60730-1 |
Automatic Electrical Controls — General Requirements |
| IEEE 802.3 |
Ethernet (BACnet/IP physical layer) |
| TIA-568 |
Commercial Building Telecommunications Cabling Standard |
| FCC Part 15 |
Radio Frequency Devices (Class A unintentional radiator limits for OT equipment) |
| BTL — BACnet Testing Laboratories |
Listed Products and Protocol Implementation Conformance Statements |
3 Submittals
3.1 Action Submittals
3.1.1 The Contractor shall submit the following for the Engineer's review and return before procurement and installation:
- Product data sheets for each server, supervisory controller, programmable controller, application-specific controller, sensor, actuator, and network device, identifying manufacturer, model, BTL listing where applicable, BACnet device profile (e.g., B-BC, B-AAC, B-ASC), and the BACnet Interoperability Building Blocks (BIBBs) supported
- A BACnet Protocol Implementation Conformance Statement (PICS) for every BACnet device on the system
- System architecture diagram showing the server / management layer, supervisory controllers, field controllers, BACnet/IP backbone, MS/TP segments, Modbus segments, and any proprietary subsystem boundaries, with physical media identified for each segment
- Network addressing plan including BACnet device instance numbers (unique across the entire system), BACnet network numbers per segment, IP addressing for BACnet/IP devices, and MS/TP MAC addresses with token-passing master count per segment
- Complete point list for the project, organized by equipment, listing each point's name, BACnet object type and instance, engineering units, default value, alarm limits, COV increment, and source (hardware input, calculated, integrated)
- Graphics intent: representative floor plans, system schematics, and equipment graphics demonstrating the visual style, navigation hierarchy, and dynamic point overlays to be used
- Schedule and alarm strategy document defining alarm classes, priority levels, suppression rules, routing destinations, and the operating-hours schedule structure
- Trend log plan listing the points to be trended, trend interval, retention period, and on-controller versus server storage
- Cybersecurity plan addressing account management, password policy, network segregation, patch management, removable media policy, remote access method, and audit logging — at a level of detail consistent with NIST SP 800-82 baseline practices
- Integration submittal for each non-BACnet integration (Modbus, proprietary): communication parameters, register or object map, gateway model, and a sample of integrated points exposed as BACnet objects to the supervisory layer
- Sequence-to-program correspondence: a mapping document showing how each item of the published sequence of operations is implemented in controller logic, with the program block or function name responsible for each step
- Riser diagram of BAS field wiring showing controller locations, cable types and lengths, conduit segments, and termination points
- Catalog cuts and product data for all damper actuators, valve actuators, sensors, and end devices proposed under this scope where not already submitted under the equipment standard that delivers them
☑ System architecture diagram (server, supervisory, field, bus segments)
☐ BACnet PICS for every BACnet device
☐ Product data for all controllers, sensors, actuators, gateways
☐ Network addressing plan (device instances, network numbers, IP, MAC)
☐ Complete point list by equipment
☐ Graphics intent (floor plans, schematics, equipment graphics)
☐ Schedule and alarm strategy document
☐ Trend log plan
☐ Cybersecurity plan (NIST SP 800-82 baseline)
☐ Integration submittal for each non-BACnet subsystem
☐ Sequence-to-program correspondence map
☐ Field wiring riser diagram
3.1.2 Submittals shall be coordinated across all controllers, network infrastructure, and integrated equipment before any item is submitted; piecemeal submittals that require multiple resubmissions due to internal inconsistency will not be accepted.
3.2 Closeout Submittals
3.2.1 The Contractor shall provide the following at substantial completion before the building automation system is accepted:
- Operation and maintenance manuals with controller programming guides, parameter reference, server software user guides, and recommended preventive maintenance intervals
- As-built drawings reflecting installed routing, controller locations, sensor and actuator locations, and any field deviations from the submitted design
- A complete copy of all controller programs, graphics files, schedules, alarm definitions, trend log configurations, and server database in the manufacturer's native backup format and in a portable form (BACnet PICS-compatible export where available)
- A point database export in a spreadsheet-readable format, listing every point with its final calibrated range, engineering units, alarm limits, and final tag name
- Calibration records for every measured sensor (temperature, humidity, CO2, pressure, flow) showing calibration date, reference instrument used, as-found reading, and as-left reading
- Network commissioning report documenting actual BACnet/IP traffic, MS/TP token-pass times, and any segment loading issues observed
- Cybersecurity closeout: list of all user accounts with role assignments, list of all installed firmware and software versions with patch dates, copy of the configured backup schedule, and a signed acknowledgement that all default and vendor-default passwords have been changed
- Functional test reports for every system, signed by the Contractor's commissioning technician and by the Commissioning Authority where one is engaged
- Training records documenting Owner personnel trained, dates, and topics covered
☑ Operation and maintenance manuals
☑ As-built drawings
☐ Complete copy of controller programs, graphics, schedules, alarms, trends, database
☐ Point database export (spreadsheet-readable)
☑ Sensor calibration records (as-found / as-left)
☐ Network commissioning report
☐ Cybersecurity closeout (accounts, versions, backup schedule, password acknowledgement)
☑ Functional test reports for every system
☐ Training records
4 Quality Assurance
4.1 Manufacturer Qualifications
4.1.1 The BAS shall be furnished by a manufacturer with a minimum of ten years of continuous experience producing direct digital control products for commercial HVAC applications.
4.1.2 The manufacturer shall maintain an ISO 9001 certified quality management system.
4.1.3 The manufacturer shall commit in writing to maintaining replacement parts, firmware support, and software upgrade paths for the proposed product platform for a minimum of fifteen years from the date of substantial completion.
4.2 Installer Qualifications
4.2.1 BAS installation, programming, integration, and commissioning shall be performed by a controls contractor authorized by the system manufacturer for the proposed platform.
4.2.2 The controls contractor shall have a minimum of five years of documented experience installing systems of similar scope and complexity.
4.2.3 The controls contractor shall employ programmers and integrators certified by the manufacturer on the specific product line and on BACnet integration.
4.3 BTL Listing
● BTL listing required for all BACnet devices (recommended)
○ BTL listing required for supervisory and primary equipment controllers; PICS sufficient for end devices
○ PICS sufficient — BTL not required (legacy systems, small projects only)
4.3.1 All BACnet devices shall be listed by the BACnet Testing Laboratories (BTL) for the claimed device profile and BIBBs.
4.3.2 A device that is described as "BACnet-compatible" but is not BTL-listed shall not be accepted unless its BACnet PICS has been submitted and the Engineer has accepted the device in writing for the specific role.
NOTE BTL listing is the only practical assurance that a device will interoperate at the protocol level with other BACnet products on the project. (4.3.3)
4.4 NRTL Listing
4.4.1 All BAS controllers, power supplies, gateways, and panels shall be listed by a Nationally Recognized Testing Laboratory to UL 916 (Energy Management Equipment) or UL 60730-1 as applicable.
4.4.2 Equipment that derives its power from a Class 2 source shall be listed for Class 2 operation per NFPA 70 Article 725.
4.5 Single-Source Responsibility
4.5.1 The supervisory, field, and integration layers of the BAS shall be furnished and installed by a single controls contractor under a single point of responsibility.
4.5.2 Where any portion of the system is delivered with packaged equipment (factory-mounted controllers on chillers, packaged rooftop units, or air handling units, or third-party submeters and indoor air quality monitors), the controls contractor shall be responsible for integration of those subsystems into the central BAS via the submitted communications interface.
4.5.3 The controls contractor shall verify that all required points are visible and operable at the operator workstation.
4.6 Pre-Installation Conference
4.6.1 A pre-installation conference shall be held before any BAS field work begins.
4.6.2 Attendees shall include the controls contractor, the mechanical contractor, the electrical contractor, the Owner's information technology representative, and the Commissioning Authority where one is engaged.
4.6.3 The agenda shall include coordination of network ports and IP addressing with the Owner IT organization, identification of separately powered subsystems and emergency power requirements, conduit and cable routing for field buses, location of controller panels in mechanical rooms, and the cybersecurity provisions that constrain remote access during construction and after substantial completion.
5 Environmental and Service Conditions
5.1 Ambient Conditions
Indoor — conditioned mechanical or electrical room
Indoor — unconditioned mechanical penthouse or above-ceiling plenum
Outdoor — weatherproof enclosure, sheltered (rooftop)
Outdoor — weatherproof enclosure, fully exposed
Wet, washdown, or corrosive process areas
5.1.1 BAS controllers and panels installed indoors in conditioned mechanical rooms shall be suitable for continuous operation in ambient temperatures from 32°F to 122°F (0°C to 50°C) and relative humidity from 10% to 90% non-condensing.
5.1.2 Controllers installed in unconditioned spaces — mechanical penthouses, parking garages, rooftops in weatherproof enclosures, exterior light court walls — shall be rated for the actual ambient extremes anticipated at the location, and any required heaters or supplemental cooling shall be included in the submittal.
5.1.3 Controllers in damp or wet locations shall be installed in NEMA 4 or NEMA 4X enclosures with the controller protected from condensation.
NOTE Field experience shows that controller failures in unconditioned spaces are concentrated in the condensation season (heating to cooling changeover and vice versa) and that enclosure heaters or anti-condensation strips significantly improve reliability where condensation is plausible. (5.1.4)
5.2 Power Supply
NOTE BAS field controllers and end devices are typically powered from 24 VAC Class 2 transformers per NFPA 70 Article 725. (5.2.1)
○ Normal power only
○ Standby generator (life safety equipment branches only)
○ Standby generator (all BAS equipment)
● Uninterruptible power supply at server and supervisory layer (recommended)
○ UPS at supervisory layer plus generator for full system
5.2.2 Multiple devices may share a single transformer where the total connected VA load does not exceed 80% of the transformer rating.
5.2.3 Supervisory controllers and gateways may require 120 VAC or low-voltage DC; all power supplies shall be sized for at least 25% reserve capacity above the connected load to accommodate future expansion.
5.2.4 A minimum of an uninterruptible power supply sized for 30 minutes of run time shall be provided for the server and any supervisory controllers that host global scheduling, alarming, or critical sequences.
5.2.5 Loss of supervisory power during a utility blip should not cause a system-wide restart; UPS protection is the minimum standard.
5.3 Seismic Requirements
5.3.1 Where required by the applicable building code, BAS panels and server cabinets shall be seismically certified or restrained per ASCE 7 and IBC for the project Seismic Design Category.
5.3.2 Where the BAS is part of a facility designated as essential or where the BAS controls life-safety mechanical equipment (smoke control fans, stair pressurization), seismic certification of the controller assembly shall be provided.
6 System Architecture
6.1 Layered Architecture
6.1.1 The BAS shall be organized in four layers, each connected to the next by a defined communications interface:
- Server / management layer. Hosts the operator interface, graphics, historian (trend) database, alarm database, configuration backup, and user account directory. May be on premises or hosted in a private cloud, with the connection between server and supervisory layer protected as a control system interface (see Cybersecurity below).
- Supervisory layer. Network controllers (BACnet Building Controllers, B-BC) that perform global control, scheduling, alarming, historical trend collection from field controllers, and inter-system integration. Supervisory controllers shall continue to execute their assigned logic when isolated from the server layer; the server is a presentation and historian layer, not a control layer.
- Field controller layer. Application-specific controllers (B-ASC) and advanced application controllers (B-AAC) at each piece of equipment — air handling units, terminal units, central plant equipment, exhaust fans, pumps. Each field controller executes the sequence of operations for the equipment it serves and continues to do so when isolated from the supervisory layer (stand-alone operation).
- Field bus and I/O layer. Sensors, actuators, switches, and equipment communications interfaces wired to field controller inputs and outputs, or networked on a field bus (BACnet MS/TP or, for specific integrations, Modbus RTU).
○ BACnet (ASHRAE 135 / ISO 16484-5) — default and required at multi-vendor interfaces
● BACnet with Modbus permitted for specific equipment integrations
○ Proprietary closed protocol with BACnet gateway at supervisory layer
BACnet/IP over dedicated BAS Ethernet VLAN
BACnet/IP over shared building Ethernet with VLAN segregation
BACnet/Ethernet (ISO 8802-3 frame format) — legacy systems only
BACnet/SC (Secure Connect) — modern TLS-protected BACnet over IP
BACnet MS/TP (RS-485, twisted shielded pair)
BACnet/IP at the field controller (where each field controller is on Ethernet)
Modbus RTU (RS-485) — equipment integration only
Mix — BACnet MS/TP for primary devices, Modbus RTU for specific equipment
NOTE BACnet/SC (Secure Connect) is the preferred backbone for new systems where the supervisory layer must traverse any network shared with non-BAS traffic, because it provides TLS encryption and mutual authentication between BACnet devices that the underlying BACnet/IP standard does not. (6.1.2)
6.1.3 Where BACnet/SC is not yet supported on all required devices, BACnet/IP on a physically or VLAN-segregated network with no routed access from the production data network is the acceptable alternative.
6.2 BACnet/IP Network
Star — Ethernet switch in each electrical/mechanical room, fiber or copper home runs to a central BAS switch
Ring — fiber ring with redundant path between primary switches
Hybrid — fiber backbone with star drops
Category 6 UTP copper to all devices within 90 m of switch
Category 6A UTP copper (10G-ready, recommended for new installations)
Multimode fiber (OM3/OM4) between buildings or to remote switches
Singlemode fiber (OS2) for runs exceeding 300 m or for future expansion
6.2.1 The BACnet/IP backbone shall be a dedicated Ethernet network for BAS use, physically separate from or VLAN-segregated from the building's production data network.
6.2.2 No general-purpose office or guest traffic shall traverse the BAS network.
6.2.3 Routing from the production network to the BAS network shall be controlled by a firewall configured for the principle of least privilege, with rules documented and reviewed annually.
6.2.4 BACnet/IP cable runs shall comply with TIA-568 for Ethernet, including 100 m maximum copper channel length and approved patch panel terminations.
6.2.5 Cable installation in plenum spaces shall use plenum-rated cable.
6.2.6 The BACnet/IP network shall not share switches or VLANs with security camera, voice, or guest networks; if physical switches must be shared, the BAS VLAN shall be configured with strict access control lists.
6.3 BACnet MS/TP Network
6.3.1 BACnet MS/TP shall be used for field controller-to-supervisory communications where individual controllers do not justify the cost of an Ethernet drop.
NOTE MS/TP runs on RS-485 twisted shielded pair, supports up to 127 master nodes per segment in the addressing range, and is practical at data rates of 38.4 kbps or 76.8 kbps. (6.3.2)
9.6 — legacy compatibility only
19.2 — legacy compatibility only
38.4 — common, conservative
76.8 — recommended for new installations
115.2 — supported by some platforms, verify all devices
32 devices per segment (conservative — best response)
50 devices per segment (typical)
64 devices per segment (heavily loaded)
127 devices per segment (theoretical maximum — degraded response)
NOTE Lower data rates increase token-pass time and degrade response on heavily loaded segments. (6.3.3)
NOTE A field-loaded MS/TP segment with token-pass times above 200 ms produces noticeably sluggish response at the operator workstation and may cause priority array writes to time out. (6.3.4)
6.3.5 The conservative loading of 32 devices per segment yields token-pass times well under 100 ms on typical platforms at 76.8 kbps and is the recommended practice for new construction.
6.3.6 Where higher densities are required, the segment shall be tested under load before final acceptance.
6.3.7 MS/TP cable shall be 22 AWG shielded twisted pair, with the shield grounded at one end only (typically at the supervisory controller).
6.3.8 Daisy-chain topology is required; star or branch topologies are not permitted.
6.3.9 End-of-line terminating resistors (120 Ω) shall be installed at both physical ends of each segment.
6.3.10 Cable lengths exceeding 1,200 m on a single segment shall be split with a repeater.
6.4 Modbus and Proprietary Integration
NOTE Modbus RTU and Modbus TCP integration is permitted where a specific item of equipment provides Modbus as its native protocol and a BACnet interface is not available or carries a significant cost premium. (6.4.1)
NOTE Examples include certain submeters, power monitoring devices, generator controllers, indoor air quality stations, and some chiller controllers. (6.4.2)
○ Embedded gateway in the supervisory controller (preferred for small integrations)
● Standalone gateway appliance (recommended for larger integrations with many points)
○ Software gateway hosted on BAS server (verify performance and recovery behavior)
6.4.3 The Modbus device shall be integrated through a gateway that maps Modbus registers to BACnet objects at the supervisory layer, so that the operator workstation sees a uniform BACnet device tree regardless of the underlying protocol.
6.4.4 Proprietary closed protocols are permitted only within a single manufacturer's product family below the supervisory layer (for example, a manufacturer's proprietary field bus connecting a packaged chiller's onboard controller to the chiller's auxiliary devices).
6.4.5 The boundary between the proprietary subsystem and the BAS shall be BACnet, and all required points shall be exposed as BACnet objects.
6.5 Stand-Alone Operation
6.5.1 Every controller in the system shall continue to execute its assigned sequence of operations when isolated from the layer above it.
6.5.2 Loss of the BACnet/IP backbone shall not cause an air handling unit's MS/TP controller to stop controlling the unit.
6.5.3 Loss of the supervisory controller shall not cause connected VAV terminal units to stop modulating their dampers and valves.
6.5.4 The system shall be designed and verified so that any single network failure produces a degradation of monitoring and global integration, not a loss of mechanical control.
NOTE This is a foundational design requirement, not an option. (6.5.5)
6.6 Time Synchronization
○ NTP server provided by Owner IT organization (preferred where IT can provide)
● Dedicated NTP appliance on BAS network (where BAS is isolated from production)
○ BAS server as authoritative time source (small systems)
6.6.1 All controllers and the server shall be synchronized to a common time source.
6.6.2 The server shall be configured as a Network Time Protocol (NTP) client to a known reliable source — either a local NTP server provided by the Owner IT organization or, where the BAS network is isolated, a stratum-2 NTP server provided by the Contractor on the BAS network.
6.6.3 Supervisory and field controllers shall synchronize from the server.
6.6.4 Time drift between any controller and the server shall not exceed 30 seconds at any time.
NOTE Trend timestamps that drift significantly are useless for fault diagnosis. (6.6.5)
7 Server and Operator Workstation
Physical server on premises (BAS-owned hardware)
Virtual machine on Owner-provided hypervisor (with IT coordination)
Private cloud hosting by BAS manufacturer (verify Owner cybersecurity policy)
Hybrid — supervisory hardware on premises, archive and reporting in cloud
Server-class Windows OS, currently supported version
Linux distribution, currently supported LTS version
Manufacturer-provided appliance OS
7.1.1 The BAS server shall host the operator interface, graphics, alarm and event database, historical trend database, schedule definitions, user account directory, and configuration backup.
7.1.2 The server may be physical or virtual, on-premises or hosted in a private cloud, provided the cybersecurity and connectivity requirements of this standard are met.
7.1.3 The server operating system shall be a currently supported version with active security update channels.
7.1.4 Operating systems past their vendor end-of-life shall not be deployed.
7.1.5 The Contractor shall identify the operating system version in the submittal and shall be responsible during the warranty period for applying vendor security patches in coordination with the Owner IT organization.
7.2 Database Backup
Daily backup to local network attached storage, 30-day retention
Daily backup to off-site cloud storage, 90-day retention
Daily local backup plus weekly off-site backup, 90-day retention combined
Continuous replication to a standby server (high-availability systems)
7.2.1 The server shall be configured to automatically back up the BAS database — controllers programs, graphics, schedules, alarm definitions, user accounts, and configuration — to a separate storage location at least daily.
7.2.2 The backup retention shall be a minimum of 30 days.
7.2.3 The backup process shall be tested by performing a full restore on a test system at substantial completion and the result documented.
7.3 Operator Workstation
NOTE The preferred operator interface for new systems is a web browser thin client accessed from standard endpoint workstations. (7.3.1)
Web browser thin client (no installed software, supported on standard endpoint workstations)
Manufacturer-installed thick client on dedicated workstation
Mobile/tablet client for field engineering
All of the above
NOTE A thin client interface allows the Owner's IT organization to manage workstations consistently and allows authorized users to access the system from any compliant endpoint, subject to the cybersecurity provisions of this standard. (7.3.2)
7.3.3 Dedicated workstations may be installed in operations centers where always-on display is required.
7.4 User Accounts and Roles
○ Local accounts on BAS server with strong password policy
● Active Directory / LDAP integration with the Owner organization (preferred)
○ SAML or OAuth federation with the Owner identity provider
○ Local accounts plus optional multi-factor authentication for engineer and administrator roles
7.4.1 The system shall support role-based access control with at least the following standard roles: operator (read and acknowledge alarms, view trends and graphics), supervisor (operator role plus override capability and schedule edits), engineer (full configuration and program editing), and administrator (engineer role plus user account management).
7.4.2 Each named individual shall have a personal account; shared accounts are not permitted.
7.4.3 Where the Owner organization operates a directory service, BAS user accounts should integrate with that service so that account lifecycle (provision, deactivate, password reset) is managed centrally.
NOTE Centralized account management is particularly important for promptly removing access when personnel leave the organization — a local-account-only system frequently retains orphaned accounts for former employees and contractors. (7.4.4)
7.4.5 Multi-factor authentication is required for any account with engineer or administrator privileges on systems accessible from outside the BAS network.
8 Graphics and Operator Interface
8.1 Graphics Hierarchy
Photorealistic equipment with three-dimensional appearance
Schematic line drawing with dynamic point overlays
Combination — photorealistic plant rooms, schematic terminal equipment
8.1.1 The operator interface shall be organized as a navigable hierarchy: a building or site landing page, floor plans, equipment system schematics (e.g., chilled water plant, hot water plant, an air handler), and individual equipment graphics with all monitored and controlled points.
NOTE Schematic line graphics generally produce more usable operator interfaces than photorealistic graphics; the purpose of an equipment graphic is to convey the current state of the system to a trained operator in seconds — the airflow path, water flow path, status of each piece of equipment, and any active alarms, and photorealistic decoration adds visual noise without conveying state. (8.1.3)
8.1.4 Where photorealism is used (commonly for client demonstration purposes), the dynamic point overlays shall be clearly readable and shall not be obscured by decorative elements.
8.2 Required Graphic Pages
8.2.1 At minimum, the following graphic pages shall be provided:
- A site or building landing page identifying the building, current outdoor conditions, system status summary (running / off / alarmed), and the count of active alarms
- Floor plans for each floor showing the location of major equipment and zones, with hotspots to navigate to zone-level detail
- A graphic for each central plant system (chilled water plant, hot water plant, condenser water plant), showing all equipment, valves, pumps, sensors, setpoints, and current readings with engineering units
- A graphic for each air handling unit, terminal unit, exhaust fan, energy recovery device, or other equipment item, showing all monitored and controlled points
- A graphic for each major integrated subsystem (chiller controller, boiler controller, packaged equipment) showing the points integrated and the current state
- A weather/outdoor conditions graphic showing outdoor air dry-bulb temperature, relative humidity, dew point, and wet-bulb temperature, with trend window
- A schedules page listing all defined schedules, current state of each schedule, and the equipment controlled
- An alarms page showing active alarms, recently acknowledged alarms, and a search interface for the alarm history
8.3 Setpoint and Override Behavior
8.3.1 Setpoint adjustments and equipment overrides from graphics shall write to the appropriate BACnet object's priority array at a defined priority level.
8.3.2 Operator manual overrides shall write at priority 8 (Manual Operator).
8.3.3 Schedule and supervisory writes shall use priorities 14–16 as appropriate.
8.3.4 Releasing an override shall release the priority slot, returning control to lower-priority programs.
8.3.5 The graphic shall display when a point is currently being overridden and at what priority, so that operators can determine why a point is not following its programmed sequence.
8.4 Engineering Units and Localization
● I-P (°F, in. w.g., gpm, CFM)
○ SI (°C, Pa, L/s, m³/h)
○ Operator selectable per user account
8.4.1 All displayed values shall include engineering units in either I-P (inch-pound) or SI units as selected for the project.
8.4.2 Mixed units within a single graphic shall be avoided.
8.4.3 Temperature shall be displayed to one decimal place; pressures to two decimal places where the magnitude is below 10, otherwise to one decimal place; flows to no more decimal places than the meter resolution actually supports.
9 Scheduling
9.1 Schedule Structure
☐ Daily schedule (Monday–Sunday with distinct profiles per day)
☐ Weekly recurring schedule
☑ Holiday and exception schedules (overrides daily/weekly)
☐ Calendar schedule (yearly recurring events, fiscal-year alignment)
☐ Event-driven schedules (triggered by external input)
☐ Demand response schedules (utility signal triggers a reduced-load schedule)
9.1.1 The system shall support occupancy schedules with at least daily, weekly, yearly, and holiday components.
9.1.2 Each schedule shall produce a discrete output (typically the BACnet Schedule object) consumed by the controllers it serves.
9.1.3 The same schedule may serve multiple controllers — for example, a "Main Building Occupied" schedule may drive air handler occupancy modes, terminal unit zone setpoints, and exhaust fan operation.
9.2 Optimum Start and Stop
● Optimum start and stop on all scheduled equipment
○ Optimum start only (no optimum stop)
○ Optimum start and stop on AHUs only (not on terminal units)
○ Not implemented (fixed pre-start/post-stop times in schedule)
9.2.1 Where required by ASHRAE 90.1 or the applicable energy code, the system shall implement optimum start and optimum stop for the air handling units and terminal units serving each occupancy schedule.
NOTE Optimum start calculates the earliest pre-occupancy startup time required to bring zones to occupied setpoint by the start of occupancy, based on indoor and outdoor conditions and a learning algorithm that adjusts the start time daily. (9.2.2)
NOTE Optimum stop terminates active heating or cooling before the end of occupancy, coasting the zone through the final occupied period. (9.2.3)
9.3 Holiday and Calendar
9.3.1 The system shall support at least 50 holidays and exception days per year.
9.3.2 Holidays shall propagate automatically to all schedules without requiring per-schedule re-entry.
9.3.3 The Contractor shall load the next two years of US federal holidays at substantial completion; the Owner shall maintain the calendar thereafter.
10 Alarming and Events
10.1 Alarm Classes and Priorities
3 levels (Critical / High / Low)
4 levels (Critical / High / Medium / Low)
5 levels (Critical / Urgent / High / Medium / Low)
Custom priority mapping per Owner requirements
10.1.1 The system shall support multiple alarm priority levels — at minimum, critical (immediate response required, life-safety or major equipment), high (response required within shift, significant comfort or equipment risk), and low (informational, response can be scheduled).
10.1.2 Each defined alarm shall be assigned a priority and a routing destination.
10.1.3 Critical alarms shall be visible on the landing page of the operator interface at all times until acknowledged.
10.2 Alarm Routing
☑ Operator workstation (always)
☐ Local alarm console at building engineer office
☐ Email — building engineering staff
☐ Email — Owner maintenance management system
☐ SMS or push notification to on-call staff
☐ Integration with Owner IT service management (e.g., ServiceNow)
10.2.1 Alarms shall be routable to multiple destinations: the operator workstation, the alarm console at the building engineer's office, e-mail addresses, SMS gateways via the Owner's notification system, and the Owner's alarm management system if one exists.
10.2.2 Routing shall be configurable per alarm priority and per time of day (e.g., after-hours critical alarms route to on-call paging).
10.3 Alarm Suppression
Parent-child suppression (when AHU is off, its downstream alarms are suppressed)
Time-delay suppression (a transient out-of-range condition shorter than N minutes does not alarm)
Manual maintenance suppression (operator places equipment in maintenance mode)
All of the above
10.3.1 The system shall provide alarm suppression rules to prevent alarm floods when a piece of equipment is off (downstream alarms should be suppressed when their parent equipment is not running) and when scheduled maintenance is in progress.
10.3.2 Suppression rules shall be documented in the alarm strategy submittal.
10.4 Required Alarms
10.4.1 At minimum, the system shall implement alarms for the following standard conditions.
10.4.2 Specific alarm limits shall be tuned during commissioning based on observed system behavior.
- Loss of communications with any field controller (delayed by at least 60 seconds to suppress transient alarms)
- Sensor out-of-range or sensor fault on any monitored input
- Setpoint deviation: each control loop alarms when its measured variable deviates from setpoint by more than a defined band for more than a defined time
- Equipment runtime status fault: commanded equipment is not running, or commanded-off equipment is running
- Filter pressure drop high
- Freeze-stat trip (any unit serving outdoor air in freezing climate)
- Duct smoke detector activation (interface from fire alarm)
- Critical space environmental out-of-range (temperature, humidity, pressure) for spaces with such requirements
- Loss of network — supervisory to field bus
- Server backup failure
- User account login failure repeated beyond threshold
11 Trending and Historical Data
11.1 Trend Collection
Change-of-value (COV) for analog points; state change for digital points (efficient storage)
Fixed polling interval — 1 minute
Fixed polling interval — 5 minutes
Fixed polling interval — 15 minutes
COV with fixed-interval fallback (recommended)
11.1.1 The system shall collect trend logs for all designated points at a configurable interval.
NOTE Standard practice for HVAC trending uses change-of-value (COV) collection for analog points, supplemented by polled samples at a fixed interval to ensure a continuous record. (11.1.2)
11.1.3 Digital state points trend on state change.
11.2 Trend Retention
30 days at original resolution; not aggregated
30 days at original resolution; 1 year at 15-minute aggregation
90 days at original resolution; 3 years at hourly aggregation
1 year at original resolution; 5 years at hourly aggregation
Indefinite, capacity-limited (recommended for large historians on cloud storage)
11.2.1 The historian shall retain trend data for a configurable period, with shorter intervals (one minute) retained for a shorter window and aggregated (15-minute, hourly) data retained for longer.
NOTE Recent high-resolution data supports fault diagnosis; long-term aggregated data supports energy reporting and warranty disputes. (11.2.2)
11.3 Required Trends
11.3.1 At minimum, the following points shall be trended at all times.
11.3.2 Additional points shall be trended during commissioning, with the trend definition retained after commissioning is complete:
- Outdoor air dry-bulb temperature and relative humidity
- All zone temperature setpoints and measured zone temperatures for spaces with separate zone controls
- All supply air temperatures, return air temperatures, and mixed air temperatures
- All chilled water and hot water supply and return temperatures, plant differential pressures, and pumping speeds
- All air handling unit supply fan and return fan speeds, duct static pressures, and damper positions
- All terminal unit damper positions, reheat valve positions, and zone airflow rates (for VAV systems)
- Energy meter readings: total electric, total gas, total domestic water, central plant flows and temperatures sufficient to calculate energy consumed per system
- All alarm history (separate from trend retention; alarm history may be retained longer)
12 Sensors
12.1 General Sensor Requirements
12.1.1 All sensors shall be of industrial or commercial HVAC grade with documented accuracy, repeatability, and range that envelopes the range of conditions to be measured.
12.1.2 Consumer-grade sensors are not acceptable for permanent installation.
12.1.3 Each sensor shall be selected so that the operating range used in the application falls within the central 60% of the sensor's stated range, where accuracy is typically best.
12.2 Temperature Sensors
○ 10 kΩ NTC thermistor at 77°F (Type II, Type III, or platform-standard curve)
● 1000 Ω platinum RTD (PT1000) — preferred for accuracy and long-term stability
○ 100 Ω platinum RTD (PT100) — industrial standard, requires three-wire wiring
±1.0°F (consumer grade — not acceptable for new installations)
±0.5°F (commercial standard)
±0.3°F (precision applications)
±0.18°F (laboratory and critical space applications)
● Averaging serpentine element (full cross-section coverage)
○ Single-point sensor (not recommended for mixed air; acceptable for outdoor air only)
● Shielded radiation shield on north side of building, away from exhaust outlets
○ Roof-mounted with sun shield, away from rooftop equipment exhaust
○ Manufacturer-supplied weather station enclosure
12.2.1 Space temperature sensors shall be located on interior walls, 4 to 5 ft above finished floor, away from supply diffusers, exterior walls, sources of heat (lighting, equipment), and direct sunlight.
NOTE Locating a space sensor on an exterior wall or adjacent to a window introduces 2–4°F of bias that destroys the calibration accuracy of the sensor. (12.2.2)
12.2.3 Duct-mounted temperature sensors in mixed air sections shall be averaging type, with a serpentine element traversing the duct cross-section, to prevent stratification error.
NOTE Single-point sensors in mixed air locations report whichever air layer the sensor happens to be in and produce control problems that look like control loop tuning issues but are actually sensor errors. (12.2.4)
12.2.5 Outdoor air temperature sensors shall be installed with a radiation shield to prevent direct solar gain from biasing the reading by 5–10°F during sunny daylight hours.
NOTE A common error is mounting an outdoor air sensor on a south-facing or roof exposure with no shield, which produces a sensor that reads correctly at night and dramatically over-reads during the day, confusing economizer and reset sequences. (12.2.6)
12.3 Humidity Sensors
● Capacitive polymer (typical commercial)
○ Chilled mirror (laboratory grade, calibration reference)
±5% RH (consumer grade — not acceptable for new installations)
±3% RH (commercial standard)
±2% RH (humidity-controlled spaces)
±1% RH (critical environments, museum, archive, healthcare clean)
NOTE Capacitive polymer humidity sensors drift over time and require periodic recalibration; typical commercial sensors are rated for ±3% RH out of the box but drift to ±5% or worse within 2–3 years if not recalibrated. (12.3.1)
12.3.2 The O&M manual shall include a recommended recalibration interval, and the Owner shall maintain a calibration program.
12.3.3 Critical humidity-controlled spaces (operating rooms, archive storage, server rooms) shall use ±2% RH or better sensors with documented annual calibration.
12.4 Carbon Dioxide Sensors
NOTE Carbon dioxide sensors are used for demand-controlled ventilation per ASHRAE 62.1 and for indoor air quality monitoring. (12.4.1)
○ Non-dispersive infrared (NDIR), single-channel
● Non-dispersive infrared (NDIR), dual-channel with auto-calibration
○ Photoacoustic (high accuracy, higher cost)
0–2000 ppm, ±50 ppm or ±5% of reading (standard DCV)
0–5000 ppm, ±50 ppm or ±5% of reading (high-occupancy spaces)
0–10,000 ppm (laboratory and industrial applications)
12.4.2 CO2 sensors shall be of non-dispersive infrared (NDIR) type, which provides the long-term stability required for DCV applications.
12.4.3 Electrochemical CO2 sensors are not acceptable for permanent installation.
NOTE Dual-channel NDIR with auto-calibration (sometimes called ABC, automatic background calibration) substantially reduces drift over the sensor's service life by periodically referencing the sensor to a clean-air baseline. (12.4.4)
12.4.5 The auto-calibration algorithm assumes that the sensor sees clean outdoor air levels of CO2 (approximately 420 ppm in 2026) at least briefly during each calibration cycle; sensors installed in continuously occupied spaces that never reach outdoor baseline may calibrate incorrectly and the auto-calibration shall be disabled in those applications.
12.5 Pressure Sensors
0–1 in. w.g. range, ±0.5% of full scale (low-pressure VAV systems)
0–3 in. w.g. range, ±0.5% of full scale (medium-pressure systems)
0–5 in. w.g. range, ±0.5% of full scale (high-pressure systems)
0–10 in. w.g. range, ±0.5% of full scale (industrial)
0–50 psig, ±0.5% of full scale
0–100 psig, ±0.5% of full scale
0–150 psig, ±0.5% of full scale
0–300 psig, ±0.5% of full scale (high-pressure systems)
12.5.1 Differential pressure sensors used for duct static pressure control shall be selected so that the operating point falls within the central 60% of the sensor range.
NOTE A sensor with too wide a range loses resolution at the operating point and produces noisy control; a sensor with too narrow a range pegs at full scale during system transients and provides no usable feedback. (12.5.2)
12.6 Airflow Measurement
Multi-port averaging thermal-dispersion array (insertion grid)
Multi-point pitot-tube grid with differential pressure transmitter
Vortex shedding (in-duct)
Not used — fan curve based airflow inference (less accurate, acceptable for non-critical applications)
12.6.1 Outdoor air airflow measurement is required for demand-controlled ventilation per ASHRAE 62.1 and is the most reliable method of verifying ventilation compliance.
12.6.2 The measurement station shall be installed upstream of the outdoor air damper at a location with adequate straight duct upstream and downstream to develop a stable velocity profile per the manufacturer's installation requirements.
13 Actuators
13.1 Damper Actuators
Electronic modulating, 0–10 VDC or 4–20 mA control signal
Electronic two-position (open/closed) for shutoff and isolation dampers
Electronic floating-point (three-wire) — legacy compatibility only
Pneumatic (existing pneumatic systems only)
● Spring return — outdoor air dampers (fail closed) and freeze-protection critical dampers
○ Spring return — return/relief dampers (fail open)
○ Non-spring-return — internal isolation dampers without freeze risk
13.1.1 Spring-return actuators are mandatory for outdoor air dampers in freezing climates and for any damper whose failed-open or failed-closed state must be controlled for freeze, life-safety, or pressurization reasons.
NOTE The added cost of spring return is small compared to the consequences of a powered actuator failing in mid-stroke during a power loss in winter. (13.1.2)
13.1.3 Actuators shall be sized for the damper's seating torque (close-off torque under operating differential pressure) plus a 25% safety margin, not for the running torque.
NOTE Undersized actuators are a chronic field problem that causes dampers not to fully close — particularly outdoor air dampers, which contribute to freeze damage and infiltration losses. (13.1.4)
13.2 Valve Actuators
Electronic modulating, 0–10 VDC or 4–20 mA
Electronic two-position (isolation valves)
Pneumatic (existing pneumatic systems only)
● Spring return — fail open (heat to coil on power loss, freeze protection)
○ Non-spring-return (no freeze risk, acceptable for re-heat coils with separate freeze protection)
● Spring return — fail closed (no cooling on power loss)
○ Non-spring-return (acceptable where no humidity or temperature consequence)
13.3 Equipment VFD Integration
13.3.1 All variable frequency drives serving HVAC equipment shall be integrated to the BAS via the network protocol specified in Hvac Variable Frequency Drives. 13.3.2 The integration shall expose at minimum the standard VFD point set: start/stop command, speed reference, run status, fault status with fault code, output frequency, motor current, motor power, accumulated kWh, accumulated run hours, and bypass status where bypass is provided.
13.3.3 The BAS shall not write speed reference at the highest priority unless the equipment standard explicitly requires it; the VFD's hardwired analog input or HOA selector shall override BAS command per the safety hierarchy.
14 Equipment Integration
14.1 Air Handling Units
14.1.1 The BAS shall control all air handling unit functions as defined in the published sequence of operations on the drawings and in Air Handling Units. 14.1.2 Standard AHU integration shall include the following points at the BAS network: supply, return, mixed, and outdoor air temperatures; supply and return humidity (where humidity control is provided); duct static pressure (VAV systems); supply fan and return fan VFD start/stop, speed, status, and feedback; chilled and hot water coil valve positions; outdoor, return, and exhaust/relief damper positions; freeze-stat status; supply and return smoke detector status (interfaced from fire alarm); filter pressure status; and any unit-specific points required by the sequence of operations.
14.2 Terminal Units
14.2.1 Where the project employs VAV or other terminal units per Air Terminal Units, the BAS shall provide a field controller at each terminal unit — typically a B-ASC application-specific controller — communicating on the field bus to the zone-level supervisory layer. 14.2.2 Each terminal unit controller shall implement the published terminal unit sequence and shall expose the following points to the network: zone temperature, zone temperature setpoints (occupied cooling, occupied heating, unoccupied), damper position, airflow rate, reheat valve or stage status, occupancy sensor input where provided, and any CO2 sensor input where DCV is implemented for the zone.
14.3 Central Plant
14.3.1 Chillers, boilers, cooling towers, pumps, and other central plant equipment shall be integrated to the BAS through the network interfaces provided by each piece of equipment.
14.3.2 The native interface shall be BACnet wherever the equipment supports it; Modbus integration through a gateway is acceptable where BACnet is not native.
14.4 Water Treatment Interface
14.4.1 The BAS shall integrate with the chemical water treatment controllers per Hvac Water Treatment to monitor conductivity, biocide cycle status, makeup flow, and blowdown flow on cooling tower systems and on closed-loop systems where chemical treatment is provided. NOTE Integration to the water treatment controller is particularly important for ASHRAE 188 compliance documentation, which requires demonstrated tracking of cooling tower operating chemistry and dispersant addition. (14.4.2)
14.5 Testing, Adjusting, and Balancing Interface
14.5.1 During commissioning per Testing Adjusting And Balancing, the BAS shall provide the TAB agent with operator-level access to override damper, valve, and fan speed setpoints for the duration of balancing. 14.5.2 After balancing is complete, all overrides shall be released and the as-balanced settings recorded as the system baseline.
14.6 Fire Alarm Interface
14.6.1 Interface to the fire alarm system per NFPA 72 shall be by hardwired contacts at the fire alarm control panel, not by network protocol.
14.6.2 The BAS shall receive smoke detection alarms (typically wired through Form C contacts at each duct smoke detector and at the fire alarm panel) and shall execute the smoke control sequence on the drawings — shutting down fans, repositioning dampers, opening or closing stair pressurization equipment.
14.6.3 The BAS shall not be the primary smoke control sequence; the fire alarm system shall command the safety sequence directly and the BAS shall mirror that state.
14.6.4 The interface to Fire Alarm Systems is a hardwired interface only, isolated from the data network. 15 Cybersecurity
NOTE The BAS is operational technology (OT) that controls building systems whose failure can affect occupant safety, productivity, and energy consumption. (15.1)
NOTE OT systems are increasingly targeted by intruders who exploit poor segregation between IT and OT networks, weak account management, unpatched embedded operating systems, and default credentials. (15.2)
15.3 The cybersecurity provisions of this standard implement the baseline practices recommended by NIST SP 800-82 for OT environments and shall be considered minimum requirements.
15.4 The Owner's IT/OT security organization may impose stricter requirements that govern.
15.5 Network Segregation
Physically separate network (dedicated cabling and switches)
VLAN-segregated on shared switching infrastructure with documented access control lists
Software-defined network segmentation (modern campuses with SDN-capable switching)
Shared with general data network — NOT ACCEPTABLE (only for documenting non-compliant existing installations)
15.5.1 The BAS network shall not share broadcast domains with the production data network.
15.5.2 Where physical separation is not practical, VLAN segregation with documented and reviewed access control lists is required.
15.5.3 The boundary between the BAS network and any other network shall be enforced by a firewall configured for the principle of least privilege — only specific protocols, ports, and source addresses required for legitimate BAS operation shall be permitted, and all rules shall be documented and reviewed at least annually.
15.6 Remote Access
No remote access — site-local operation only
Owner-managed VPN with multi-factor authentication
Manufacturer-provided cloud connector with strong authentication (verify Owner policy)
Jump host inside Owner DMZ, MFA required, session recording enabled
15.6.1 Remote access for monitoring, troubleshooting, and software maintenance shall be through an Owner-managed VPN or a Owner-approved jump host with multi-factor authentication.
15.6.2 Direct internet exposure of BAS servers, supervisory controllers, or workstation web interfaces is not permitted.
15.6.3 Manufacturer cloud connectors shall not be installed without explicit Owner approval and shall be configured to require authentication on every session.
15.7 Account Management
Minimum 12 characters, complexity required, 90-day rotation, no reuse of last 12
Owner Active Directory policy (preferred where AD integration is used)
Phrase-based policy with multi-factor authentication on privileged accounts
15.7.1 Default and vendor-supplied passwords on every device — server operating system, supervisory controllers, network switches, gateways, programmable controllers, and any device with an authentication interface — shall be changed before the device is placed in service.
15.7.2 The Contractor shall provide a signed statement at substantial completion that all default credentials have been changed; the Owner's representative shall be entitled to spot-check a sample of devices to verify.
15.7.3 User accounts shall follow the principle of least privilege: each named user shall have only the role required to perform that user's function.
15.7.4 Account creation, modification, and deactivation shall follow a documented procedure that includes an audit trail.
15.8 Patching and Firmware Updates
● Server OS patched monthly per Owner IT policy; controller firmware patched per manufacturer security bulletins
○ Server OS patched quarterly with documented exception review; controller firmware patched annually
○ Patches applied only when a specific vulnerability is identified affecting installed equipment (least preferred)
15.8.1 The Owner and the controls contractor shall jointly maintain a patching cadence during the warranty period and the Owner's ongoing service contract thereafter.
15.8.2 Embedded controller firmware is not patched as frequently as server software but shall be updated promptly when the manufacturer issues a security bulletin affecting installed firmware.
15.8.3 Firmware updates shall be tested on a non-production controller before being deployed widely on the installed base.
15.9 Audit Logging
☑ User login and logout events
☐ Failed login attempts
☐ Configuration changes (programs, schedules, alarm definitions)
☐ Setpoint and override write events
☐ Account creation, modification, deletion
☐ Backup and restore events
☐ Patch and firmware update events
15.9.1 Audit logs shall be retained for a minimum of 90 days and shall be readable by the Owner's security operations team in a standard format.
15.9.2 Where the Owner operates a centralized security information and event management (SIEM) platform, logs shall be forwarded to that platform via syslog or comparable mechanism.
15.10.1 Removable media (USB drives, optical media, SD cards) shall not be used on BAS servers, workstations, or programming laptops without explicit Owner authorization.
15.10.2 Each authorized removable media event shall be logged.
15.10.3 Software updates and configuration files shall be transferred via the Owner-approved file transfer mechanism rather than via removable media wherever practical.
16 Point Counts and System Sizing
NOTE The total point count is among the most consequential sizing parameters for a BAS — it drives controller hardware sizing, MS/TP segment count, server resource allocation, and licensing where the manufacturer licenses by points. (16.1)
100100000
100250500100025005000100002500050000100000
Default: 5000 points
Per drawings
5050000
50100250500100025005000100002500050000
Default: 2500 points
Per drawings
5050000
50100250500100025005000100002500050000
Default: 2500 points
Per drawings
16.2 Point counts shall be developed from the equipment schedules and the sequences of operation and verified during shop drawing development.
16.3 System capacity shall include a minimum of 20% spare capacity above the design point count, at every level — spare hardware I/O on field controllers, spare bandwidth on MS/TP segments, spare server CPU and memory, and spare licensing where applicable.
NOTE Spare capacity is required to absorb the routine additions and renovations that follow substantial completion; a system delivered at 100% of its licensed capacity becomes a barrier to building operations changes within the first year of service. (16.4)
17 Field Installation
17.1 Controller Panel Installation
NEMA 1 — indoor, clean, dry locations
NEMA 12 — indoor, dust-tight (typical mechanical rooms)
NEMA 3R — outdoor, sheltered (rooftop)
NEMA 4 — washdown, condensation-prone
NEMA 4X — corrosive environments, cooling towers, coastal
17.1.1 Field controller panels shall be mounted in clean, dry, accessible locations near the equipment they serve.
17.1.2 Maintenance access to each panel shall include at minimum a 36 in. clear working space in front and adequate clearance above and to the sides for cable entry and panel door swing.
17.1.3 Panels shall not be installed in locations subject to vibration without vibration isolation, in damp or wet locations without NEMA 4 or 4X enclosures, or in classified hazardous locations without appropriately listed enclosures.
17.2 Wiring Practices
● 22 AWG shielded twisted pair, foil shield with drain (plenum-rated where required)
○ 20 AWG shielded twisted pair (heavily loaded segments or long runs)
○ Manufacturer-specified cable (verify against published cable type)
17.2.1 Control wiring shall be installed per Conductors And Cables and Raceways And Conduit and per NFPA 70 Article 725 for Class 2 circuits. 17.2.2 Control wiring shall not be installed in the same raceway as line-voltage power conductors.
17.2.3 Minimum separation between Class 2 control wiring and power wiring shall be 12 in. where parallel runs are unavoidable; where crossings are unavoidable, conductors shall cross at right angles.
17.2.4 Network cables (BACnet/IP, MS/TP) shall be routed separately from variable frequency drive output cables to avoid coupling of PWM switching noise.
17.2.5 Shield drain conductors shall be terminated to a clean ground at one end only — typically at the supervisory controller — to prevent ground-loop currents from flowing through the shield.
NOTE Both-end grounding of MS/TP shields is a common source of intermittent communications faults that are difficult to diagnose because the symptom appears as random device dropouts. (17.2.6)
17.3 Sensor and Actuator Installation
17.3.1 Sensors shall be installed in accordance with the manufacturer's installation instructions and per the location requirements of this standard.
17.3.2 Each sensor shall be calibrated against a reference instrument at startup; the as-found and as-left readings shall be recorded on the calibration form.
17.3.3 Sensors that read more than the specified accuracy off from the reference shall be replaced, not adjusted out by software offset.
NOTE Persistent software offsets disguise sensor drift and undermine future calibration. (17.3.4)
17.3.5 Actuators shall be installed with the actuator shaft coupled to the damper or valve shaft per the manufacturer's instructions, with the coupling tight, the shaft aligned, and the stroke verified by commanding fully open and fully closed from the BAS.
17.3.6 Damper actuator end-of-stroke positions shall be set so that the damper fully closes and fully opens at the actuator end positions, with no residual leakage when commanded closed and no over-travel when commanded open.
17.4 Identification and Labeling
Engraved phenolic labels, mechanically attached
Vinyl thermal-transfer labels rated for service environment
Brass or stainless tags on stainless lacing (corrosive environments)
17.4.1 Each controller panel shall be permanently labeled with the panel designation, the equipment or zone it serves, and the BAS device instance number.
17.4.2 Each cable entering a panel shall be labeled at the panel termination with the cable's source and the circuit it carries.
17.4.3 Each field-mounted sensor and actuator shall be labeled with its point name as it appears in the BAS database.
17.4.4 Labels shall be machine-printed and applied to a surface that will remain visible and intact for the service life of the equipment.
18 Testing and Commissioning
18.1 Factory Acceptance Test
○ Not required — small project, no central plant control panel pre-assembly
● Required — central plant control panel(s) pre-assembled and tested before shipment
○ Required and witnessed by Owner or Commissioning Authority
18.1.1 Where the project includes a complete plant control system fabricated and tested at the controls contractor's facility before shipment, a factory acceptance test (FAT) shall be performed.
18.1.2 FAT shall verify hardware assembly, power-up of all controllers, communication between controllers and supervisory devices, basic graphic page rendering, and a smoke test of the loaded programs.
18.1.3 FAT does not replace field functional testing.
18.2 Field Functional Testing
☑ Point-to-point verification — every hardware input and output, sensor calibration, actuator stroke
☐ Network communication verification — BACnet PICS compliance, MS/TP token-pass, BACnet/IP routing
☐ Sequence functional test — each step in each sequence on the drawings
☐ Alarm verification — each defined alarm triggered and routed correctly
☐ Schedule verification — schedules executed and equipment responds as commanded
☐ Trend verification — defined trends collecting data and accessible from the historian
☐ Failure mode test — induce loss of communications and verify stand-alone behavior
☐ Cybersecurity verification — default passwords changed, network access controls applied
18.2.1 Field functional testing shall verify every point in the system and every sequence in the sequence of operations document.
18.2.2 Functional tests shall be performed by the controls contractor and witnessed by the Commissioning Authority where one is engaged.
18.2.3 Each test shall produce a documented test result — pass, fail, or deficiency noted with a corrective action.
18.3 Sensor Calibration
● NIST-traceable certificate, calibration within last 12 months
○ Manufacturer factory calibration accepted (within last 6 months)
○ On-site comparison to recently calibrated reference
18.3.1 Every measured sensor shall be calibrated at startup against a reference instrument of known accuracy traceable to NIST or equivalent national metrology institute.
18.3.2 Calibration shall be performed at conditions representative of the sensor's normal operating range, not at room temperature only.
18.3.3 Calibration records shall be retained as a closeout submittal and shall identify each sensor by its system tag, the reference instrument used, the as-found reading, and the as-left reading.
18.4 Demonstration and Training
8 hours (1 day) — small system, single operator
16 hours (2 days) — typical commercial building
24 hours (3 days) — larger system or campus
40 hours (1 week) — full operator certification program
18.4.1 The Contractor shall conduct documented training for Owner personnel covering the operator interface, alarm response, scheduling, override and release procedures, basic trending and reporting, and the cybersecurity procedures that constrain Owner operations (account management, removable media, remote access).
18.4.2 Training shall be delivered after substantial completion and shall include at least two sessions to accommodate shift coverage.
18.4.3 Training materials including written procedures, recorded sessions, and a quick-reference card for common operations shall be left with the Owner.
18.4.4 Training shall be tailored to the actual installed system, not delivered from a generic manufacturer slide deck.
19 Warranty
1 year from substantial completion (parts and labor)
2 years from substantial completion (parts and labor)
1 year parts and labor, plus 90 days of software updates and parameter tuning
Extended — 5 years parts, 1 year labor
19.1 The warranty shall cover defects in materials and workmanship under normal service conditions for the specified period from the date of substantial completion.
19.2 The warranty shall include a fine-tuning period of at least 90 days following substantial completion during which the controls contractor responds to operational issues — control loop instability, alarm tuning, schedule adjustments, graphics changes — that emerge as the building moves through its first occupancy cycle.
19.3 Tuning during this period shall be at no additional cost; this is among the most valuable warranty provisions in a BAS contract and shall not be omitted.
19.4 The manufacturer shall provide a written commitment that replacement parts, firmware, and software upgrade paths will remain available for the installed product platform for a minimum of ten years from the date of manufacture.
19.5 Software Support
☑ Server operating system security patches
☐ BAS application software updates and security patches
☐ Controller firmware updates
☐ Graphics changes (limited hours per month)
☐ Schedule and alarm adjustments (limited hours per month)
☐ Trend log additions (limited hours per month)
☐ Annual cybersecurity review
20 Spare Parts
☑ 10% spare hardware I/O modules of each type installed
☐ One spare controller of each model installed
☐ One spare power supply of each type installed
☐ One spare network switch of each model installed
☐ Five spare space temperature sensors
☐ Two spare humidity sensors of each type installed
☐ Two spare CO2 sensors of each type installed
☐ One spare damper actuator of each size installed
☐ One spare valve actuator of each size installed
20.1 Spare parts shall be of the same model and firmware revision as the installed equipment.
20.2 Spare controllers shall be retained in original packaging with documented storage conditions.
NOTE Long-term storage of unused controllers in damp or hot conditions degrades electrolytic capacitors and battery-backed memory and shortens the spare's useful service life. (20.3)
21 Identification and Labeling
21.1 Each controller panel shall include a permanent nameplate identifying the panel by its BAS designation, the equipment or zone it serves, the supervisory controller it reports to, and an emergency contact for service.
21.2 Inside each panel door, a current single-line diagram and point schedule shall be permanently mounted in a clear pocket.
21.3 The point schedule shall be updated whenever the panel is modified.
21.4 All BAS network cables — BACnet/IP copper, BACnet/IP fiber, MS/TP cable, Modbus cable — shall be labeled at every termination with cable type, source, and destination.
21.5 Field sensor and actuator cables shall be labeled at the controller termination with the point name as it appears in the BAS database.
NOTE Cable labeling at the controller termination shortens the most common BAS troubleshooting task — finding the cable that connects to a given point — from minutes to seconds. (21.6)
21.7 A laminated system overview drawing shall be permanently mounted in the main mechanical room or the BAS operator workstation room, showing the supervisory network topology, the location of each controller panel, and the contact information for the controls contractor and the manufacturer's technical support organization.
21.8 This drawing shall be updated at any system change and shall remain current throughout the service life of the system.