Who this is for: a chief engineer or facilities director in New York or New Jersey whose building automation system shows few or no alarms while the building keeps producing complaints, overnight energy use or equipment that runs when it should not. The decision: whether the problem sits in the equipment, in the way it is controlled, or in what the system can see, before anyone approves controls work, a replacement or a capital request. The engineering here is the same in both states; where money is involved, the article points to the page that covers each state.
A quiet front end and a building that is not right
The graphics are green. The alarm list is short. And yet the third floor is cold every Monday morning, the chillers start on mild spring nights, the gas bill climbs in a month when it should fall, and the same tenant calls about the same office. When the system and the people in the building disagree, it is worth assuming the people are describing something real.
A building automation system reports what its sensors and its programming tell it, and it reports a wrong value with the same confidence as a right one. A space sensor that has drifted three degrees still reads a clean number. An override someone set during last summer’s heat wave stays in place until someone releases it. A schedule written for a tenant who left years ago still starts the air handler at five in the morning. Alarms that fired too often were disabled, so they no longer fire at all. None of that shows up as a fault on the front end, because from the system’s point of view nothing is broken.
How often this happens
Until recently, the national labs described how often specific HVAC faults occur as largely undocumented. That has changed, and the newer studies agree on the main point: problems are common, and most of them are in how the building is operated rather than in failed equipment.
- When Pacific Northwest National Laboratory analysed automation-system data from 151 commercial buildings, it found ways to improve operations in almost every one. Each of the 20 most common problems showed up in between a quarter and three-quarters of the buildings, and about 40% of them were in air handlers; the rest were in schedules, chilled- and hot-water distribution and zone controls (PNNL, 2021).
- A 2023 Berkeley Lab analysis of fault-detection records from 317 buildings found that on an average day, 40% of air handlers and 30% of terminal units reported at least one fault. The most common air-handler fault involved the supply-air temperature set point, reported on 55% of units; cooling-coil and heating-coil valve faults followed at 35% and 22%. In terminal units, zone temperature sensor faults and abnormal zone temperatures each showed up on 46%. These are faults as reported by fault-detection software, so some will be false positives, but the scale is hard to dismiss.
- An older Berkeley Lab study of 24 monitoring-based commissioning projects (2009) found problems in HVAC equipment at 65% of sites and in air handling and distribution at 59%. Those figures say where problems were found, not how often any one fault occurs.
What fixing it is worth
The same research measured what correcting operational problems saves. These are medians across many buildings, so they describe the population rather than your building, and they belong to the literature rather than to anything ieComfort promises.
- The 69 buildings in the PNNL study that carried out the fixes saved a median of 12% of their annual energy.
- Across about 1,300 existing buildings, commissioning cost a median of $0.26 per square foot in 2017 dollars, saved a median 6% of whole-building energy, and paid back in a median of 1.7 years. In two utility programs in that study, 87% of the measures were HVAC, and scheduling, resets, set point and sequence changes made up nearly all of them (Berkeley Lab, 2020).
- Organizations in the Department of Energy’s Smart Energy Analytics Campaign that used fault detection and diagnostics saved a median 9% of annual energy, with paybacks of about two years (Berkeley Lab, 2020).
- The Department of Energy’s Federal Energy Management Program reports that re-tuning at federal sites typically saves 5% to 25% of annual energy, with simple paybacks of 0.3 to 3.5 years, finding the savings mainly through the building automation system in buildings whose systems are in proper working order.
This has a name: re-tuning, and its bigger sibling, retro-commissioning
Finding and correcting the way a building automation system runs the building, without replacing equipment, is called re-tuning. Pacific Northwest National Laboratory organizes it around four principles: turn it off, turn it down, stop heating and cooling at the same time, and reduce outdoor air and infiltration. Retro-commissioning is the structured version: a documented study of how the existing systems operate, followed by corrections and verification. ASHRAE’s commissioning guidelines (Guideline 0 for the process, Guideline 1.1 for HVAC) describe how that work is planned and recorded. In New York City, Local Law 87 requires retro-commissioning of buildings over 50,000 square feet every ten years and requires the deficiencies to be corrected.
What a responsible review looks at
A review that ends in “the BAS looks fine” has usually looked only at the front end. The useful work happens where the system meets the building. It follows the same four steps every time.
Observe
- Points against the field. For a sample of points, does the sensor exist where the graphic says it does, is it wired, and is the value plausible against a handheld reading?
- Overrides. Which points are in manual or operator override, who set them, and when. A long-standing override can leave a sequence doing something quite different from what its documentation says.
- Trends. A few weeks of trend data covering occupied and unoccupied hours, and a cool and a warm stretch if possible: supply-air temperature against its set point, valve positions, fan speeds, outdoor-air damper position, zone temperatures.
- Schedules and set points. Equipment start and stop times against how the building is occupied today, and set points against what the tenants are being promised.
- Alarms. Which alarms are enabled, which have been suppressed, and who receives them.
- Sequences. What the controllers are programmed to do, compared with the sequence of operations on file, looking for simultaneous heating and cooling, economizers that never open and resets that were never configured.
Decide
Separate symptoms from causes. A cold office might be a failed valve actuator, a drifted sensor, a schedule, a set point or an air handler that cannot keep up. Each has a different fix and a different price. The ENERGY STAR Building Upgrade Manual sets out the order that keeps decisions honest: retro-commission the existing systems first, reduce loads second, and only then size and replace equipment, because the first two steps change the answer to the third.
Act
Make the approved corrections: release overrides, repair or replace the sensors that lie, rewrite schedules, fix sequences. Where sequences are rewritten, ASHRAE Guideline 36-2024 publishes standard high-performance sequences of operation for HVAC systems, written to maximize efficiency, keep control stable and support real-time fault detection. If an incentive depends on the work, the utility’s pre-approval comes before any of it starts.
Verify
Functional tests and post-change trends show whether each correction did what it was meant to do. Without that step, corrections can quietly come undone: an override returns, or a schedule gets widened for one complaint and never narrowed again. Verification ends with someone named to own the system.
When the system itself is the limit
Sometimes the review finds that the building automation system cannot see what it needs to. Field controllers may talk BACnet over a twisted-pair network (MS/TP), the building network (BACnet/IP) or the newer BACnet Secure Connect, which adds encrypted, authenticated connections; older systems may use a manufacturer’s own protocol behind a gateway. A gateway can only pass along what a device reports, and gateways handle schedules, alarms and trends poorly. A BTL listing tells you which BACnet functions a device passed testing for, and no more. When the limit is the architecture rather than the programming, the question becomes how open the next system should be, which is the subject of How to Choose Between Open and Proprietary Building Controls.
Ongoing monitoring is a separate decision with its own scope. Verified data and alarms can be integrated into your existing BAS or a separately scoped platform, subject to point availability, network approval, cybersecurity, alarm ownership, functional testing and commissioning.
What you receive from a review
A written set of findings: where the system and the field disagree, a status list of the points that matter, and prioritized actions, each tied to the evidence behind it. The review recommends the next responsible step. Often that is a controls correction rather than new equipment; sometimes it is new equipment, and then the decision is made on measured load rather than an old nameplate. What a review can cover depends on the building: point availability, protocols, network and cybersecurity approval, what the equipment can do, site access and who owns the alarms. Those are settled before the work is priced.
How the work is funded differs by state. In New York City, Con Edison pays for new or expanded automation on the energy it saves and NYSERDA helps pay for studies; in New Jersey, each utility funds controls through its custom track, and JCP&L and Atlantic City Electric pay the commissioning firm directly for retro-commissioning. The details, with program years, are on the controls and building automation page.
The next step
Start with a controls re-tuning review. Send a recent utility bill and the equipment list; if you have them, add the BAS point list, a screenshot of the front end or a trend export. A missing document tells us something too, and sending them is not a commitment. The review finds the next responsible decision rather than assuming a replacement. Send the building details (until the screening tool is live, this is a short intake form).
Related reading: How to Choose Between Open and Proprietary Building Controls · Before You Replace the Chiller, Rooftop Unit, or Cooling Tower, Prove What the Building Needs · New York City Local Law 87
Sources and dates
- Katipamula, S., Underhill, R.M., Fernandez, N., Kim, W., Lutes, R.G. and Taasevigen, D.J., “Prevalence of typical operational problems and energy savings opportunities in U.S. commercial buildings,” Energy and Buildings 253 (2021) 111544, Pacific Northwest National Laboratory.
- Crowe, E. et al., “Empirical analysis of the prevalence of HVAC faults in commercial buildings,” Science and Technology for the Built Environment 29 (2023) 1027–1038, Lawrence Berkeley National Laboratory.
- Crowe, E. et al., “Building commissioning costs and savings across three decades and 1500 North American buildings,” Energy and Buildings 227 (2020) 110408; Kramer, H. et al., Proving the Business Case for Building Analytics, Lawrence Berkeley National Laboratory, October 2020.
- Mills, E. and Mathew, P., Monitoring-Based Commissioning: Benchmarking Analysis of 24 UC/CSU/IOU Projects, LBNL-1972E, June 2009; national-lab literature on fault prevalence, 2020–2021.
- U.S. Department of Energy, Federal Energy Management Program, Re-tuning Challenge fact sheet (July 2025); Pacific Northwest National Laboratory, Re-tuning Measure Guide (April 2023).
- ASHRAE Guideline 0 and Guideline 1.1 (commissioning process); ASHRAE Guideline 36-2024 (high-performance sequences of operation); U.S. EPA, ENERGY STAR Building Upgrade Manual; BACnet Testing Laboratories listing program; S. Bushby (NIST), “Communication Gateways: Friend or Foe?”, ASHRAE Journal, April 1998.
- Last reviewed October 28, 2026. Next review January 28, 2027.