Building Automation System HVAC Checks Worth Running Before Heating Season
Somebody overrode an air handler schedule for a Saturday event in 2024, and that override is probably still running. Nobody catches it because the graphics page shows green equipment doing what it’s told, and the gas bill creeps up slowly enough to look like it’s just the weather. Your building automation system HVAC sequences were written for the building as it was when it was commissioned. Tenants, hours, and space use have all changed since then.
Fall pulls those problems into the open, because the changeover from cooling to heating runs sequences that sat idle throughout the summer. If your heating ventilation and air conditioning equipment share a controls platform with lighting and other electrical equipment, one audit covers more ground than a mechanical inspection does.
What the savings evidence actually shows
Pacific Northwest National Laboratory calls this re-tuning, and it’s mostly low-cost or no-cost changes to control HVAC settings rather than to install new hardware. PNNL reports building energy savings that typically range from 5 percent to 25 percent when these measures are applied together. Energy cost savings run on the order of $0.185 per square foot per year. Simple payback takes between 0.3 and 3.5 years.
A published study of the same approach across 26 federal office buildings and courthouses found 12.1 percent average annual energy savings. That worked out to about $0.151 per square foot per year. The researchers note those 26 buildings had very efficient baselines before any of the work started. In other words, the savings didn’t come from fixing broken buildings. They came from correcting control settings in buildings that were already running well, which is the case for most of the properties we see in Columbus.
Seven building automation system HVAC faults worth checking
The list below covers the faults that show up most often in Columbus commercial buildings during a fall walkthrough. Each one is visible from the BAS building graphics or trend logs, so you can check them before you call anyone.
| Control fault | How it shows up in trends | Typical fix | Why it costs money |
|---|---|---|---|
| Schedules left in occupied mode. | Fan status on overnight and weekends. | Reset the schedule and audit override expirations. | Fans and reheat run for an empty building. |
| Simultaneous heating and cooling. | Reheat valve open while cooling coil is active. | Correct zone setpoints and deadband. | Two systems fight each other all day. |
| No temperature deadband. | Heating and cooling setpoints within a degree. | Widen deadband to at least 3 degrees F. | Zones cycle between modes constantly. |
| Static pressure setpoint fixed high. | Constant duct pressure regardless of demand. | Enable pressure reset based on damper position. | Fan power scales with the cube of airflow. |
| Supply air temperature stays fixed. | Flat discharge temperature year round. | Add outdoor-air-based reset. | Cooling then reheating the same air wastes both. |
| Economizer damper stuck. | Mixed air temperature ignores mild outdoor air. | Repair actuator and relink the sequence. | Free cooling gets replaced with paid cooling. |
| Failed sensors reading a default | A flat line in the trend log | Recalibrate or replace the sensor | Every downstream sequence acts on a wrong number |
Trend logs are the fastest place to catch these issues. Pull a week of data on fan status, discharge air temperature, and valve position, then look for flat lines and for anything that runs when the building is empty.
Where code now pushes automation system BAS design
Ohio’s commercial energy code follows the 2021 IECC, and section C403.2.3 requires HVAC fault detection and diagnostics in buildings of 100,000 square feet and larger. The Department of Energy’s summary of the 2021 commercial provisions spells out exactly what that means. You need permanently installed sensors, sampling at least once every 15 minutes, and automatic fault identification and notification. The system also has to give prioritized repair recommendations and send them to remote staff.
That code section applies to new work rather than existing buildings, so an older Columbus property isn’t out of compliance today. It does tell you where the market is heading. When you replace a controller or expand a system, specifying FDD-capable points now avoids a rework later.
On the sequence side, ASHRAE Guideline 36 gives you preprogrammed control sequences instead of one-off custom logic. ASHRAE’s own write-up of the 2021 edition makes the case plainly: custom sequences often get simplified during programming, then don’t get properly debugged or commissioned, and building performance suffers. Asking a controls contractor to quote Guideline 36 sequences is a reasonable line item on any retrofit.
Running the audit without shutting the building down
Start with occupancy. Print the current schedule for every air handling unit and compare it against actual building hours, then look at every override on the system and find out who set it and when. Overrides with no expiration are the single most common finding.
Move to setpoints next. Check the space temperature setpoints against your written standard and confirm the deadband. Verify that the unoccupied setback and setup are enabled. Zones with a local adjustment need limits, because a 68-degree request from one occupant can drag reheat across a whole floor.
Finish with the sensors. Compare BAS readings against a handheld instrument at a few points, including outdoor air, mixed air, discharge air, and space temperature in two or three zones. A sensor drifting by three degrees defeats every reset sequence you set. Our building and energy management team runs this walkthrough as a scheduled service. It pairs well with the mechanical work covered under commercial maintenance.
Document what you change. A dated log of setpoint and schedule edits is what lets you connect a utility bill shift to a specific action, and it stops the next contractor from undoing your work.
Frequently asked questions
Q: How often should we audit our building automation system? A: Twice a year fits most Columbus buildings, once before heating season and once before cooling season. Buildings with tenant turnover or heavy event schedules should add a quarterly schedule review.
Q: Do we need new controls hardware to get these savings? A: Usually not. PNNL’s re-tuning work targets low-cost and no-cost control changes, which means most of the savings come from settings and sequences you already own.
Q: What’s the difference between a BAS and building management software? A: A BAS controls equipment directly through field controllers and sensors. Building management or analytics software sits on top and flags faults from the same data. Analytics tools find problems, but somebody still has to fix the sequence.
Q: Can integrating HVAC with lighting controls save more? A: It can, mostly by sharing occupancy data so both systems respond to the same signal. The savings depend on how much of your floor area sits empty during scheduled occupied hours.
Q: Our building is under 100,000 square feet. Does the FDD requirement apply? A: Not under the 2021 IECC threshold. You can still specify fault detection voluntarily, and many controls platforms include basic alarming at no extra license cost.
Q: How do we know an audit worked? A: Compare weather-normalized energy use for the same months before and after. Keep the change log next to the utility data. Raw gas and electric bills move too much with weather to tell you much on their own.
Fall is a short window, and control problems get expensive once the heating load arrives. Ohio Heating’s controls and mechanical teams work together on commercial properties across Columbus, so you can get a second set of eyes on your building automation system HVAC sequences before that happens. Call 614-863-6666 or start with our BAS system page to see what the audit covers.