What building automation system work involves
A building automation system (BAS), also called a building management system (BMS) or an energy management and control system, is the network of sensors, controllers and software that runs a building’s HVAC equipment and, at many sites, lighting, exhaust fans and energy meters. Service work touches four layers.
- Sensors. Space temperature, humidity, carbon dioxide, duct static pressure, supply and outdoor air temperature.
- Controllers. Network or supervisory controllers, plus unit controllers on rooftop units, air handlers, terminal boxes, boilers and chillers.
- Output devices. Actuators, valves, dampers, relays and variable frequency drives that carry out each command.
- Software. The front end that holds operating schedules, setpoints, alarms, trend logs and user accounts.
Most systems communicate over a protocol. BACnet is the open data communication standard for building automation and control networks, maintained by ASHRAE as ANSI/ASHRAE Standard 135, with 135-2024 the current edition. It lets controllers from different manufacturers share data. Many portfolios also carry proprietary systems that need the manufacturer’s software tools, which limits which providers can work on them.
Common service requests include a controller showing offline, equipment running after closing, one zone too hot or too cold, programming lost after a power outage, a flood of nuisance alarms, a locked-out user account and integration of a replacement rooftop unit.
Codes, standards and requirements for building automation systems
No national code sets a service interval for a building automation system. The requirements that do apply come from local law, standards and federal guidance.
- Retro-commissioning in New York City. Local Law 87 requires buildings over 50,000 gross square feet, and tax lots with two or more buildings that together exceed 100,000 gross square feet, to complete an energy audit and retro-commissioning every ten years and file an Energy Efficiency Report with the Department of Buildings. Retro-commissioning confirms that energy systems are functionally tested and operate to the owner’s needs, which in practice runs through the controls.
- Energy codes and permits. When controls are replaced or added during a remodel, the authority having jurisdiction decides which energy code and permit requirements apply. Providers confirm this before work starts.
- Cybersecurity. CISA’s Cybersecurity Best Practices for Industrial Control Systems calls for an inventory of all control system hardware and software, network segmentation, no persistent remote vendor or employee connections to the control network, a catalog of all remote connections that is monitored, testing of security patches offline before installation, and tested backups of system data and configurations. Facility First applies these practices to building controls.
- Energy performance. The U.S. Department of Energy states that high-performance controls have been shown to reduce HVAC energy use in commercial buildings by 30 percent. Pacific Northwest National Laboratory reports that 10 to 30 percent of energy used in commercial buildings is wasted through improper and inefficient operation, and its Building Re-Tuning approach targets no-cost and low-cost operational fixes.
Preventive maintenance schedule for building automation systems
Controls drift. Schedules fall out of step with trading hours, sensors lose calibration and manual overrides stay in place long after the reason for them has passed. Planned work catches these faults before they turn into comfort complaints, equipment wear and higher utility bills, and it gives each location a dated record of what was checked and changed.
| Task | Recommended frequency | Basis |
|---|---|---|
| Review operating schedules, holiday calendars and manual overrides against trading hours | Monthly, and before each holiday period | Facility First program default, adjusted per site |
| Review active alarms, trend data and offline devices | Monthly | Facility First program default, adjusted per site |
| Adjust temperature setpoints for seasonal changes | Each season | ENERGY STAR checklists for commercial buildings |
| Review start-up time, power-down time and equipment sequencing | Each season | Task: ENERGY STAR checklists. Frequency: Facility First program default, adjusted per site |
| After-hours check of what is running while the location is closed | Quarterly | Task: ENERGY STAR checklists. Frequency: Facility First program default, adjusted per site |
| Calibrate thermostats and space temperature sensors | Annually | Task: ENERGY STAR checklists. Frequency: Facility First program default, adjusted per site |
| Back up controller programming and system configuration, and test a restore | Quarterly, and after every programming change | Task: CISA ICS best practices. Frequency: Facility First program default, adjusted per site |
| Review remote connections and user accounts; remove accounts no longer needed | Quarterly | Task: CISA ICS best practices. Frequency: Facility First program default, adjusted per site |
| Review and install security patches and firmware after testing | As released, reviewed quarterly | CISA ICS best practices; manufacturer instructions |
| Update the inventory of controllers, software and firmware versions | Annually | Task: CISA ICS best practices. Frequency: Facility First program default, adjusted per site |
| Retro-commissioning | Every 10 years for covered New York City buildings; elsewhere as set in the program | NYC Local Law 87 |
The authority having jurisdiction, the manufacturer and the property’s insurer can require more frequent service, and each location’s schedule is set in its program and recorded on every visit.
Signs a building automation system needs service
- Lights, fans or rooftop units running after the location has closed
- Utility bills rising with no change in hours or operations
- Repeated comfort complaints in one zone while the rest of the building is fine
- A sensor reading that does not match a handheld meter
- Points left in manual override or “hand”
- Trend data that has stopped updating, or controllers shown as offline
- Alarms acknowledged every day with no work order behind them
- Schedules that were never updated after a change in trading hours
Records to keep
- Points list, network drawings and sequences of operation
- Inventory of controllers, software and firmware versions
- Dated backups of all programming
- The approved schedule and setpoint standard for each location
- User account list and a log of remote connections
- Calibration results and sensor replacements
- Alarm and trend reports used to close out work orders
- Retro-commissioning reports and Energy Efficiency Reports where Local Law 87 applies
How Facility First runs building automation system service across a portfolio
- Request. Submitted through the platform or by phone, with screenshots of the alarm or reading where available.
- Triage. Facility First confirms the system manufacturer, protocol, warranty and priority. Where the program includes read access to the front end, the provider reviews alarms and trends before going to site.
- Dispatch. A vetted controls provider qualified on that manufacturer and protocol in the location’s market receives the work order.
- Completion. The provider documents the work with photos and screenshots of every changed schedule, setpoint or sequence, and saves a new backup.
- Verification and invoice. The work is checked against the request and the location’s standard, then invoiced in one format.
Approval limits set by the client decide what proceeds automatically and what is quoted first. Portfolio-wide changes, such as a new holiday schedule, are issued once and tracked location by location. For planning, see the preventive maintenance checklist and work order management.
What affects the cost of building automation system work
- Number of points, controllers and devices
- Manufacturer, protocol and whether proprietary software tools are needed
- Age of the system and availability of replacement parts
- Programming changes versus hardware replacement
- Integration with new equipment, lighting or meters
- Network and cybersecurity work coordinated with the client’s IT team
- Access to roofs, ceilings and mechanical rooms, and after-hours scheduling
Building automation systems for retail stores, restaurants and offices
Retail stores. Schedules must follow trading hours, holiday hours and early openings for deliveries. Smaller stores often run rooftop units from networked thermostats or a single controller, so one schedule standard across the portfolio does most of the work. In malls, the landlord may control some systems, and the boundary is confirmed before dispatch.
Restaurants. Kitchen exhaust and makeup air must run together, dining rooms need stable comfort through long hours, and refrigeration alarms may route through the same system. Work is scheduled outside service periods.
Offices. Larger buildings use air handlers and terminal boxes with many more points, tenants request after-hours heating and cooling, and covered New York City buildings carry Local Law 87 deadlines. Controls work is coordinated with building management and tenant leases.
Frequently asked questions
What is a building automation system?
A building automation system is the network of sensors, controllers and software that runs a building’s HVAC equipment and often its lighting and meters to a schedule. It also records trends and raises alarms when equipment or conditions fall outside set limits.
What is the difference between a BAS, a BMS and an EMS?
The terms overlap and are often used for the same system. Building management system is the common term outside the United States, and an energy management system usually describes the same controls with a stronger focus on metering and energy use.
How often should a building automation system be serviced?
Facility First programs review schedules, overrides and alarms monthly, adjust setpoints each season, calibrate sensors annually and back up programming quarterly. Covered New York City buildings also require retro-commissioning every ten years under Local Law 87.
Can any controls provider service any system?
No. Open systems built on BACnet can be serviced by many qualified providers, but proprietary systems often need the manufacturer’s software and a provider authorized to use it.
Should a building automation system be connected to the internet?
CISA advises segmenting control networks, avoiding persistent remote connections for vendors and employees, and cataloging and monitoring every remote connection. Remote access is set up to those practices, in coordination with the client’s IT team.
Does a building automation system save energy?
It can. The U.S. Department of Energy states that high-performance controls have been shown to cut HVAC energy use in commercial buildings by 30 percent, but savings depend on correct schedules, setpoints and sensors.
Sources
- ASHRAE BACnet Committee: BACnet, ANSI/ASHRAE Standard 135
- U.S. Department of Energy: Building Controls
- Pacific Northwest National Laboratory: Building Re-Tuning
- ENERGY STAR: Checklists for saving energy in commercial buildings
- CISA: Cybersecurity Best Practices for Industrial Control Systems
- NYC Department of Buildings: LL87, Energy Audits and Retro-Commissioning