A facility manager we work with in Southfield found out the hard way that his Building Automation System (BAS) had been overriding a stuck damper for six weeks. The dashboard showed green. The zone was 15 degrees off setpoint the entire time. Nobody caught it because the software said not to look.

A BAS will tell you exactly what its sensors are wired to report and nothing more. It has no way of knowing whether the roof actually needs walking.

Sensors, Schedules, and Not Much Else

Here is what the system in Southfield could actually see: a supply air temperature, a return air temperature, and a damper position. That was the whole picture available to anyone checking the screen. A BAS, sometimes called a Building Management System (BMS), is the network of sensors, controllers, and software that schedules equipment, adjusts setpoints, and logs data across a building’s mechanical systems. It turns rooftop units on and off on a schedule. It modulates dampers to hit a temperature target, and logs run hours and fault codes so someone can look back later.

It does not listen for a bearing starting to whine, and it does not notice a coil caked in cottonwood fluff. That kind of inspection only happens if a person does it. A refrigerant charge running 10 percent low will not throw a fault code on most systems until the compressor is already stressed, so the system just quietly runs less efficiently and logs nothing unusual.

Two Ways a Building Goes Quietly Wrong

A thermostat sensor reading two degrees warm will quietly push an entire zone cold, and the BAS has no way of knowing it’s wrong. It only relays what the sensor tells it. That’s sensor drift, and it’s the same mechanism that let the Southfield damper run wrong for six straight weeks.

We’ve walked into buildings with 400 unacknowledged alarms stacked in the queue. That’s what alarm fatigue looks like in practice. A poorly tuned BAS throws so many nuisance alerts that staff stop watching the queue at all, and the one alert that actually matters gets buried with the rest. Past that volume, the alarm log isn’t functioning as a warning system. It’s just noise scrolling by that nobody reads.

Some Problems You Have to Feel, Not See

You cannot smell a burning belt through a dashboard. A technician can put a hand on a compressor housing and feel that something’s wrong, or catch a bearing whine two weeks before it fails; these are sensations no sensor is wired to pick up. Automation is genuinely good at scheduling and setpoint logic, which is a different skill entirely from noticing trouble before it ever becomes a fault code.

The buildings that get the most out of their BAS treat it as one input among several, not the whole picture. That means someone actually reviewing trend data monthly instead of only reacting to red alarms, and it means a technician still walking the mechanical room and the roof on a schedule regardless of what the dashboard says.

Is Anyone Actually Reading the Trend Logs?

Five minutes glancing at a dashboard does not count as an audit. A real one means pulling raw trend logs, not just the summary screen, and looking at how a zone’s actual temperature tracked against setpoint over a full week, including nights and weekends when nobody was watching. It also means checking sensor calibration against a handheld reference thermometer at a sample of points throughout the building, because a sensor can drift two or three degrees over a few years without ever throwing an error.

A lot of buildings are still running the alarm thresholds the original installer set a decade ago, tuned for a tenant mix and occupancy pattern that no longer matches the building. An alarm set to trigger at a 5 degree deviation might have made sense for a warehouse and makes no sense for a medical suite two tenants later, and nobody goes back to check.

What We Told the Southfield Team

Start by pulling six months of trend data on your highest-cost zones and look for slow drift rather than sudden spikes. Ask your controls contractor to reduce nuisance alarms to a manageable number so the ones that matter stand out. Put a recurring line item in your maintenance plan for a technician to physically verify what the BAS is reporting, at least twice a year, because a screen full of green does not mean a building full of good equipment.

In the retrocommissioning work we have done, it is common to find at least one zone still running a schedule built around a tenant who moved out years ago. That was true in Southfield too. Once a technician actually walked the roof, the fix was a twenty-minute damper repair. The six weeks before that call, not the repair itself, is what actually cost the building money, and none of it ever showed up on the dashboard that kept telling everyone the zone was fine.