Direct Digital Controls Commissioning | Building Automation Systems - Preface –This article is not all inclusive of everything required to properly commission a control system. I wrote this because of my observations of a colleague and their frustration on a seemingly never-ending project for which the colleague called me in as a consultant to complete the project for the controls. My colleague’s background was lacking in experience for controls whereas my background does not suffer from this lack of experience in both controls engineering and commissioning control systems. Anyhow, buckle your seat belts, this is a long piece where I cover a lot of ground although I feel it is not complete. It is simply too long to add to and I will likely write an accompanying article in the future when I have time from my busy schedule. Comments are always appreciated in the comments section below.
Direct Digital Controls Commissioning | Building Automation Systems - On many commercial construction projects the HVAC, lighting, electrical, and other systems including life and health are controlled by direct digital controls (DDC). Otherwise referred to as building automation systems (BAS), building monitoring systems (BMS), or energy management systems (EMS). These systems can be complex without proper understanding. It is important before the building is turned over to the owner, that these systems are commissioned properly. Or otherwise set up and tested to ensure they operate properly. This includes ensuring the operators are trained in its use and are given proper access levels to monitor equipment and systems DDC controls in the building.
Direct Digital Controls Commissioning | Building Automation Systems
Controls Commissioning Standards
There are written standards for commissioning including for controls commissioning (ASHRAE, PECI, BCA for both Cx and Retro-Cx). These standards are required by various governmental agencies to qualify for benefits or achieving a specific label so that the building owner can qualify for tax breaks. There are various levels a building can achieve to qualify for these benefits but it is dependent on the design and includes a commissioning requirement to obtain this label. It is referred to as LEED or Leadership in Energy Efficient Design. EnergyStar requirements are also included on some projects. This subject goes beyond the scope of this article but it is a set of basic requirements that need to be met to qualify and one of the requirements is commissioning. Including controls commissioning.
The standards are written by EPA, DOE, and third-party independent professional organizations including the BCA or Building Commissioning Association and LEED. The requirements are further refined by other parties in their specific discipline. The standards meet or exceed what is required of the government and other organizations that write these standards. The goal is to build an energy efficient building that is good for the environment and surpasses energy-efficiency standards from the past. Additionally, a system that works as designed and is operated and managed by competent operators.
Direct Digital Controls Commissioning | Network Structure and Equipment Identification
A big part of this process is to first be competent in the subject matter for direct digital controls and secondly, know the important steps in testing the control system as you go along. Some of the testing for the control systems is done during functional testing of individual pieces of equipment or systems the DDC monitors and controls. Another part is a basic review of the network structure, documenting the network structure, and ensuring that everything on the network is visible on the interface for the BMS systems. Understanding this allows the Cx engineer to see that an identification or naming of the equipment has been properly done. This is important for the operators of the building.
In the network structure, there are several microcontrollers. These microcontrollers are typically linked to each other with a network wire. The network wire runs to a parent controller. The parent controllers are hooked to a grandparent controller. The grandparent controller is linked to a server which in some cases serves as the main interface for the entire control system. Each microcontroller from the children all the way to the grandparent is assigned an address. This is a MAC address (a unique identifier in a network) and it can be cross-referenced in the DDC database to a particular piece of equipment. This allows identification of the equipment for quick responses in case of trouble with the equipment or device.
Direct Digital Controls Commissioning | Points, Navigation, Alarms, and Graphics
Controls contractors typically sell their jobs by points. The customers buy so many points that offer additional features and options in both the equipment controls and the software platform. This is all set up by a control engineer and purchased features and control points are shown in the software. Other features not purchased are hidden or the end users are locked out from using these additional features if they are not purchased. All features purchased need to be checked out and tested to ensure the owner gets what they paid for from the controls contractor.
On the interface for the controls, the screen should be organized in such a way that it is intuitive and easy to navigate for the operators. Graphics should be representational of the equipment. If an air handler has three coils then the graphics need to match. Additionally, all the control points need to match the graphics. If there are three coils then likely there will be three actuators controlling the water flow through the coils. If the actuators are analog then a percentage indication of the actuator/valve position needs to appear on the screen. And yes, I’ve been on jobs where the graphics did not even come close to matching or an analog device was shown as a binary or digital (two-position) device.
More on Interface, Alarms, and Graphics:
- Alarms should be clear and not overwhelming. In some instances, when the system sends out multiple alarms, operators will likely ignore them. Thought should be given to creating a hierarchy of an alarm system for the controls. Alarms can be used in such a way to alert operators of bigger problems before they occur. This structure of the alarm system needs to be set at a level where too many alarms don’t overwhelm the operators.
- Alarm responsibility and workflow - this is setting up a procedure where alarms are verified and the problem resolved to prevent the alarm from reoccurring. This method should be defined and in written procedure usually done on a shift by shift basis for operators. Alarms can have various levels depending on the type of equipment the alarm serves: Critical, Urgent, and Warning of a developing problem.
- A method of quick-review needs to be set up so operators can take a quick look at the entire control system and see developing problems. There are some control manufacturers that use thermal-graphics that overlay the floorplan. Color indication of green means all is good. Yellow means something is not exactly right, orange means impending trouble and red is trouble. That is one way, another way is a simple table to see that all zone setpoints are good by reviewing columns within the table.
- Any manual overrides that have occurred in the system need to be indicated on the individual equipment graphic and on a detail page of overrides. Overrides are generally done when performing troubleshooting or maintenance procedures and it is not uncommon for someone to forget to release the manual override when they have completed their tasks.
Direct Digital Controls Commissioning | Access, Trends, and Schedules
Access | Building Automation Systems Commissioning
Access levels are assigned to operators to allow them specific monitoring and control of the entire system. Access levels can be set up to prevent an operator from viewing certain information or performing specific functions. For example, where the building owner purchased a specific feature such as energy monitoring and metering for billing purposes. There is likely not a need for an operator to have access to that feature. It can be set up to give an operator basic minimum monitoring of the systems all the way to allowing operators to make changes to setpoints and even the program itself.
These access levels need to be assigned on a person by person basis based on their level of competency and knowledge within the operations department. A detailed user profile system can be written and used to assign specific access for roles within the organization. You don’t want someone to have access levels where they will do something detrimental to the entire system such as delete important files or reprogram a controller to have it malfunction. Very important data is stored in the program and deleting this data or changing a value can throw it out of whack and cause the system to not operate properly. You don’t want a secretary or operator apprentice to have the same access level as the building engineer.
DDC Trends | Building Automation Systems Commissioning
Since there are memory limitations to most microcontrollers for holding collected data the server needs to be set up to collect important trends of systems operation. Most controllers have memory limits in the kilobyte range but most servers can hold gigabytes and even terabytes. While trend data will not require gigabytes or even terabytes it is important to collect specific data so that the equipment operation can be reviewed and action is taken to tweak the system. Trends can also be set up to find problems or for troubleshooting.
Schedules | Building Automation Systems Commissioning
This will require a complete review of the entire systems and what is controlled by the control system. This is set up in conjunction with the buildings operational schedule which should include weekends, holidays and after hours shifts. Some considerations for this include:
- Water heaters - does a commercial building really need several water heaters cycling on and off when the building is unoccupied? An insulation blanket along with a schedule for the water heaters will suffice in most cases but it needs a review for off hours or low occupancy.
- Lighting systems - there are many solutions for this including scheduling, motion sensors, and even sunrise and sunset scheduling for parking lots. Photovoltaic sensors can automatically turn lights on and off along with motion sensors. The point being, when no one is present that lights can shut off automatically wither with motion sensors or scheduling during occupancy.
- HVAC systems - these can also be shut down during low or no occupancy situations depending on the buildings use. Of course, if its a mission-critical facility such as a data center or a telecom building the schedules should be disabled. Manual overrides can be done programmatically in case someone works late. If someone is in the office working late and they are uncomfortable they can change the setpoint on the thermostat. This will wake the system up and provide some level of comfort for that zone or the occupied zones. This can be set to expire after a set time so the system goes back to sleep when the worker is not present. Most modern control systems offer a smart learning control system the will learn the limitations of the equipment. The allows the control system to determine the proper time to bring everything online in a specific sequence for morning warm-up. This means if all the workers arrive at 8 a.m. then all set points are achieved by 8 a.m. no matter the weather conditions outdoors.
DDC Security and Remote Access | Direct Digital Controls Commissioning
For reasons stated previously and other reasons, the systems need to be physically secured to prevent random access by others who may or may not harm the system. This includes access settings as stated above to the controls software access and to the server itself. The room where the server is located needs to have access control for responsible maintenance operators and management staff only. A serious approach to security begins with a written plan and proper implementation of the plan. Remote access is also necessary for upper and middle management in some cases. Remote access can give management the ability to make a decision from home or any remote location. If the problem is serious enough on-call staff or an outside contractor can be summoned to rectify the problem. In some cases, the problem may be minor and not require attention until morning. This has benefits and can save money and wasted time.
A secure network and security procedures should be done to prevent hackers or other malicious actors from accessing the system. Work with the IT department for the remote network security access. Most large companies have an IT department and they are fully aware of basic and advanced security procedures to prevent security problems.
Extra Preprogrammed Controllers | Direct Digital Controls Commissioning
A proper stock of extra controllers that have been preprogrammed needs to be seriously considered and implemented if required. A procedure needs to be written on how to properly install the controller in the event a controller fails. Things such as wiring standards, setting the MAC address, calibrating, and mounting need to be written in a procedure so an operator can change a controller in the event one fails. A replacement controller needs to be ordered and if the failed controller was under warranty an RMA done to ensure proper credit. In some cases, this is a requirement to meet certain standards. Mission-critical facilities have this requirement and it is documented by the commissioning team to show they meet the requirements.
Documentation | Direct Digital Controls Commissioning
A library or organized way of keeping procedures for operators need to be made for reference. Everything from basic set up of everything described here to emergency operations to basic maintenance procedures is kept in this organized library. This is typical in facilities that are mission critical but can also be implemented in other types of commercial buildings. This library can also include a disaster plan in the event of some catastrophe.
The library can include:
- control drawings
- final blueprint drawings from construction
- original equipment and component submittals
- a basic list of control points
- maintenance procedures
- procedures for troubleshooting
- a procedure for changing a controller or attached device such as an actuator or sensor
- how to set up and view trends
- how to set up and view schedules
- equipment lists and O&M manuals for the equipment
- access levels and access hierarchy
Everything needed so an operator with a decent skill level can walk in and take care of things quickly and efficiently. If there is something they do not understand they have quick access to reference materials in the library so they can resolve any issue.
Physical Inspections | Direct Digital Controls Commissioning
In addition to the above, direct digital control commissioning also includes a physical inspection of the controls, the wiring and wiring methods, the sensors, and overall workmanship of the installation. Panels should be clearly labeled for identification including the breaker panel for the main power of that panel. Panels and wiring should be neat and all grounding wires landed properly. In some cases, plastic sleeves inside the panels hold the drawings and other pertinent technical reference documents for a technician or operator to check problems that may occur. Some of the physical things to inspect are:
- Is the panel protected from damage including water damage?
- Are the wires, controllers, relays, etc.. labeled properly?
- Is the panel labeled properly?
- Is the wire protected at penetrations?
- Is the circuit breaker location listed and is it labeled properly?
- Does the panel door close and lock to restrict access?
- Does the overall installation look professional?
Testing Sensors and Actuators | Direct Digital Controls Commissioning
Testing input and output devices is an important step in commissioning direct digital controls. Many of the sensors are very important to the proper operation of the control system. If a pressure sensor is not calibrated properly or not functioning properly how can it possibly offer precise control for the output device such as a variable frequency drive (VFD) or damper actuator position? Status sensors not properly working will give false statuses and cause problems including false alarms. This is typically done on the point-to-point checkout by the controls contractor but may be witnessed by the commissioning team. The controls contractor provides the commissioning team with a point-to-point checkout list and schedule. Everything is documented to ensure compliance.
- Are the dampers opening in the proper order for the sequence of operation?
- Are the valve actuators opening and closing the valves properly? Are they floating or two-position?
- Are freeze stats installed properly and does the equipment follow the proper sequence when the freeze stat is tripped?
- Do the VFD’s ramp up and down properly?
- Are the PID loops tuned and offer proper smooth operation?
- Do the VAV boxes respond properly under a given set of set points?
- If the control system is integrated with a foreign device (such as a proprietary chiller control panel) are all the points mapped properly and does the control system properly read those points?
All these things and more (depending on the installation and equipment) need to be physically checked and tested to ensure proper installation and operation. Again, depending on all the specifications, the design of the system, and the points list will depend a lot on various factors being physically checked and tested in a static and functional test of the equipment.
Additional Requirements Overview | Basic Building Cx | Direct Digital Controls Commissioning
- Include seasonal testing for controls commissioning as the equipment will work differently under different conditions.
- Deferred testing is done when a piece of equipment does not work as designed and needs to be replaced or repaired to bring it up to standards. Personal experience example: this happened once when a chilled water storage tank did not perform as designed. The tank did not meet the owner’s requirements to provide enough cooling capacity for the data center load in the event of a chiller failure. More capacity had to be added and that took time. More time than the original scope of the project so change orders were processed and after the additional capacity was added the Cx team returned to test the system to the owner’s requirement.
- Review all submittals and drawings for accuracy during and after construction.
- Attend factory witness testing as required.
- During the commissioning process, a deficiency list is kept of everything found to be deficient. Referred to as a commissioning punch list, the Cxa or commissioning authority tracks this list to ensure all items are satisfactorily completed before the final result is approved. This list is included in the final report so that problems during construction are documented. If the same problems reoccur, there is documentation. This helps resolve future like-problems efficiently. In some cases, this also fits in the category of deferred commissioning described above. The punch list is derived during the process of pre-functional and functional commissioning and can be rectified before functional/integrated testing is completed. Otherwise, it goes to deferred commissioning.
- Manage and schedule all commissioning meetings including attending MEP meetings. Daily reports of the commissioning progress are used in the meetings to schedule commissioning, complete deferred commissioning tasks, and to provide a means of setting a schedule to complete tasks within the project.
- Ensure the sequence of operations is kept up to date.
- Depending on the type of project, ensure all equipment and component deliveries are made and stored according to requirements. Example: on a LEED project, materials and equipment need to be stored to keep the equipment and materials out of the elements such as foul weather. This ensures the integrity of the equipment and materials and protects it from damage and mold etc….
- Witness, confirm, and document tests by outside parties such as test and balance and other specialized contractors. Any outside testing companies that certify equipment, offer calibration services or certify installation are documented by the commissioning team during the construction and testing phase of the systems.
- Reviews Basis of Design, Design Intent, perform design reviews using Basis of Design to clarify and expand Design Intent and using all that to build a commissioning plan for the construction phase.
- Work with the controls and mechanical contractors to schedule a Test and Balance contractor to precisely set flow according to specifications. Work with the Test and Balance crew to resolve issues along with the controls and mechanical contractor.
BAS Additional Testing and Verification | Direct Digital Controls Commissioning
After the equipment is installed the controls contractor installs their systems. In some cases, the equipment is delivered with the microcontrollers preinstalled in the equipment. This makes it easy for the contractor to simply install conduit and run wire for power and communication to the equipment back to the main control panel. Some controls contractors will have a contract with the electrical contractor to install all the panels and run the conduit for the controls. The controls contractor does this to save on manpower and overhead of the skilled labor need to perform those functions. When the electrical contractor has completed the contracted infrastructure and wiring, the controls contractor sends in a team to start everything up after some basic checks. Programs are loaded and startup of the equipment and controllers are done. The controls technicians have to configure the software to match the sensors and output devices in the system.
This is referred to as a point-to-point checkout of the components in the system. It ensures proper operation, calibration, and configuration are completed so the system works as designed. The commissioning team verifies this is done by witnessing and documenting the process. There are standards for calibration of sensors and components that the controls contractor must meet to satisfy this part of the commissioning process for specialized buildings. These standards come from NIST or the National Institute of Standards and Technology and other organizations such as NIST. This requires additional documentation and verification by the commissioning team and the controls contractor.
Conclusion | Direct Digital Controls Commissioning
After all the sensors, components, and controllers have been looked at and individually tested for calibration and functionality, the entire system is tested as one integrated system. Each piece of equipment has a documented control strategy and the overall DDC system has a documented control strategy. There are many different areas and lots of details that one will need to look at and document in the commissioning of a direct digital controls system. If this is done thoroughly and properly the operators and the owner will benefit from it. Commissioning is a systemic process that involves documenting every factor of the construction process including basic inspections and testing of the equipment and systems. Direct digital controls are complex systems so direct digital control commissioning needs to be as thorough as possible to ensure these complex systems operate as designed.
Direct Digital Controls Commissioning
Direct Digital Controls Commissioning | Building Automation Systems
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