The importance of monitoring machine schedules

Maintaining a commercial building is not easy. The number of technical systems and their complexity has increased considerably in order to keep a high quality of service for the tenant, and to lower energy usage and environmental impact. At the same time, there is pressure on the operations team to keep maintenance costs low, both in investments and man-hours spent.

For many commercial buildings, the tenant is typically only present some of the time. A school or office will primarily be occupied during the day-time, whereas a theater or cinema may primarily have visitors during the evening.

To operate the building in an energy-efficient way, it is critical to ensure that ventilation, heating and cooling-systems (HVAC) run only when the building is occupied. Some very modern buildings use demand-driven control, but the most widespread approach is still time-based scheduling.

There are several ways to realize a time-based schedule, and different buildings and sub-systems use different approaches. Some of the most common ones are:

  • Using a dedicated electromechanical timer unit (digital or analog)
  • Using logic blocks in a Programmable Logic Controller (PLC)
  • Using configurable functionality in an Air Handling Unit (AHU)
  • Using a central Building Management System (BMS)

Of course, none of these systems are perfect – and over the days and years that a building operates, failures do happen.

Example of configured weekly schedules around occupancy times. Here using a Building Management System (WebCtrl).
Example of configured weekly schedules around occupancy times.
Here using a Building Management System (WebCtrl).

Failure to follow schedule

Building Operations Managers report many different cases that cause them problems with schedules not being followed. Here are some examples from our own experience.

Case 1. A service technician performed maintenance on an Air Handling Unit (AHU) and disabled the timer during testing. The technician forgot to enable it again before leaving, which left the AHU constantly on. Because the operations team is not present outside the working hours, no one noticed that the ventilation was on all night until several months later, wasting a lot of costly electricity.

Air Handling Units are among the equipment where schedule failures are most common and costly.


Case 2. A set of chillers in the cooling central of a building were connected to the BMS (Building Management System) and were supposed to follow the same schedule as the ventilation system that it fed into. However, occasionally the communication would silently fail - a common occurrence with BMS systems - and the chillers would stay on even though the ventilation system was off or not in cooling mode. This wasted energy and caused excessive wear on the compressors in the chillers.

Case 3. A building had an Air Handling Unit that would trigger the frost guard some mornings in the winter time, causing the startup sequence to fail. There was no BMS in the building, so the AHU would often stay off without alarm. On several occasions, the tenants experienced cold offices and complained. To prevent this, the operations team resorted to performing a physical check that AHUs have started every single morning, wasting a lot of man-hours.

Equipment that doesn’t follow its intended schedule is a common and costly occurrence. The causes of this error ranges from system communication issues, component failures, to human errors. 

Have you seen similar challenges in your buildings? Contact us to hear how Soundsensing Condition Monitoring can help.

Consequences of schedule failures

The most common consequences of undetected schedule failures are dissatisfied tenants and wasted resources.

Problem 1. When the equipment is off when it should be on, it cannot fulfill its intended function for the tenants. In the case of a ventilation system, that means poor indoor air quality, with CO2 and room temperatures reaching unacceptable levels. When the situation becomes so bad that the tenant needs to report the issue in order for it to be fixed, the damage has already been done: They feel that the operations team has failed. If such incidents happen several times or combine with other failures (real or perceived), it will lead to poor tenant satisfaction, increasing the risk of them abandoning their contract.

Problem 2. When the equipment is on when it should be off, it causes unnecessary costs by operating for no reason. The energy costs of ventilation, cooling and heating systems tends to be a considerable portion of the overall operating costs of a building. Systems running overtime can easily become a substantial extra cost.

Equipment also has a higher chance of malfunction while running, and equipment failures outside of building occupancy times will take longer time to detect. This means that systems running outside a schedule has a higher risk of developing serious problems. An example would be a water leak that goes undetected for many hours.

Automatically detecting schedule failures

With an automated Condition Monitoring system in place, schedule issues (i.e. equipment running when it shouldn’t) can be caught automatically within a few hours. That gives the operations team time to either fix the issue before the tenant experiences a problem, or notify the tenant that they are aware of the problem and have started fixing it. The tenant gets the feeling that they are well taken care of, instead of grumbling among themselves about undiscovered errors. It also prevents equipment running unnecessarily for long periods of time – saving energy and money. 

The Condition Monitoring system by Soundsensing uses a combination of vibration and sound sensors. These data sources are rich indicators for not only the state of the equipment being monitored, like how worn the components are, but also whether the systems and components are running or not. The sensors measure continuously every few minutes. This gives 24/7 coverage of the condition of the equipment.

The system automatically learns the operating schedule from the sensor data. This allows it to function independently of a BMS, which avoids complicated and costly integrations. It also enables usage for buildings and systems which do not have a centralized BMS. It also works for any brand and make of the equipment, making it suitable for all buildings.

Schedule anomaly detected on Monday 06.03.2023
Top: Vibration level of machine, with the normal levels indicated in green.
Purple: Learned operating schedule of the machine.
Grey: Actual machine state.

On detecting a deviation from the schedule, an alarm is automatically triggered.

Alarms can be sent directly to janitors and managers, or the system can be integrated with existing work-order management systems.

Alarm from Condition Monitoring system in case of a detected schedule failure.

Our customers use Soundsensing to monitor their equipment in commercial buildings. Besides detecting failures to follow schedules, it can also detect mechanical issues and let you avoid mechanical failures.

One of our ventilation system lost its configuration for the schedule, and was constantly on.
We had sensors from Soundsensing on the system, got an alert and was able to fix the issue within 1 day.
Without this system in place, we would probably not have caught this for many weeks.
This has happened several times before, and wasted a lot of money on electricity.

- Building Operations Manager for a property management company operating more than 100 buildings in Oslo, Norway

Get in touch with us to learn more about condition monitoring. We’re happy to give you a quote on how much energy you can save by detecting faulty schedules, or how you can impress your tenants by detecting and fixing errors before they even notice.

Contact us