What if, without even visiting a building, it was possible to look deep into its corners and crevices to shine a light on operational problems that could drive energy savings? While Building Automation Systems (BAS) can be utilized to do just that, many people are not taking full advantage of their systems. Think of the BAS as a “flashlight” used to inspect operational problems that need to be corrected through enhanced control programming. Problems can be identified that require time histories to detect energy waste, such as: incorrect scheduling, not using setback modes during unoccupied periods, ineffective economizer operation and temperature / pressure resets that are either not programmed or used in a limited manner.

 

There are a number of things BAS users can do to get the most of their systems.  Here are two examples:

 

Example 1: Better Scheduling

 

The graph below shows an example of using BAS trend data to identify an Air Handling Unit (AHU) in a building that has poor scheduling. The site is an office building that is occupied Monday-Friday from 8:00 am to 6:00 pm. A quick review of the trend shows that the air handling unit supply fan operates continuously, providing an opportunity for significant energy savings by adding in a schedule.

 

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(Graph courtesy of the Pacific Northwest National Laboratory, operated by Battelle for the U.S. Department of Energy).

 

The second graph (below) shows another AHU in the building that is scheduled off during weekends; however, there appears to be additional opportunity to tighten up the schedule during the week and reduce the number of hours the AHU operates.

 

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(Graph courtesy of the Pacific Northwest National Laboratory, operated by Battelle for the U.S. Department of Energy).

 

Using trended data provided by the BAS is a way to quickly identify how building systems are operating, and where opportunity exists to improve the energy performance of the facility.

 

Example 2: Resetting Duct Static Pressure

 

Another common control retuning measure that can be identified through analyzing BAS graphs is resetting duct static pressure.  Duct static pressure (discharge air) is often used to control AHU fan speed and ensure adequate airflow to each zone. If the static pressure is set too low, some zones may experience comfort problems due to lack of air flow. If duct static pressure is set too high, problems occur such as: excessive AHU fan energy use, high noise levels in the ceiling or at the diffusers coming from Variable Air Volume box, higher chiller load and greater fan and belt wear.

 

The graph below illustrates an AHU that has a reset schedule programmed into the BAS; however, after analyzing the trend data coupled with field measurements, the set-point and programming was improved. As seen by the date stamp starting at 6/11, the trend shows a distinct profile change that follows the reprogramming. This is a good example of using trend data to identify a problem and to verify that improved performance is actually achieved and persists over time.

 

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(Graph courtesy of the Pacific Northwest National Laboratory, operated by Battelle for the U.S. Department of Energy).

 

Even More Opportunities Exist

 

The examples provided here are just the beginnings of what can be achieved. By leveraging the tremendous power of the BAS in your facility, many control optimization strategies can be identified that will generate significant energy cost savings, while improving occupant comfort.  In addition, by using continuous monitoring of trend profiles through the high level analytics that are available in cloud based platforms today, this improved performance and energy savings can be maintained over time.