Controls Conundrum

Controls Conundrum

Why don’t smarter controls always make smarter buildings? The answer has to do with system design and operation. By James Piper, Building Operating Management magazine.

Building temperature control systems, like most building systems, have been growing smarter. Today’s systems offer more capabilities to reduce operating costs while providing a better environment for the building’s occupants. Although some of today’s control systems offer greatly enhanced capabilities and are highly successful, others fall short of expectations — in some cases, far short.

In these buildings, facility executives are quick to blame the control system itself for being unreliable or too complex to work effectively. In an attempt to make the systems work, components are disconnected, control actions bypassed, and systems placed in manual operation. Eventually, so many changes are made to the original control system that it is impossible for maintenance personnel to figure out just what is going on. So the control system is upgraded or replaced, and the entire cycle starts over.

Too frequently, the problems in operation don’t lie in the control system itself. Rather, they are the result of how the systems are operated. In those cases, upgrading or replacing the control system is not the solution. What’s needed are steps to ensure that the system is properly designed, installed, operated and maintained.

Off to a Good Start

Too often, system design is left up to the building’s designer with little or no input from those who will be using the building. Without adequate information on the activities that will be performed in various spaces as well as the needs of the occupants, system designers tend to follow a cookie-cutter approach, mirroring system designs they completed in the past. Control systems that are most successful are the ones where the owners, end-users and operators were involved in the design process from the beginning.

That involvement should include commissioning. Commissioning is not a glorified building walk-through. Rather, it is a process that begins early in the design phase of a project and extends to well after completion of construction. It requires participation of the entire project team, including the owner, architect, engineer, general contractor and the control system subcontractor. When performed properly, commissioning will reduce life-cycle costs while ensuring the quality and performance of the control system.

Without commissioning, errors in system installation and setup can go undetected and uncorrected, often for years. In many cases, errors in system installation are misdiagnosed as equipment or system operational errors, causing maintenance personnel to make unnecessary adjustments and repairs, actions that further complicate and mask the original problem.

Commissioning of control systems offers a number of benefits. For one thing, it helps ensure that all sensors in the system are properly operating and calibrated. It also identifies equipment and component malfunctions at the time of system startup. What’s more, commissioning ensures that all control strategies are properly sequenced and helps to ensure the quality and the performance of the installed systems. Commissioning also helps to avoid the lengthy shakedown period that most new construction projects must go through to identify system bugs and defects.

In spite of these benefits, commissioning is too often one of the first items cut when construction and renovation projects are behind schedule or over budget. The reason is plain and simple: Commissioning of building control systems is an expensive and time-consuming process. In commissioning, all proposed system designs must be reviewed and evaluated. Construction is more closely monitored, requiring additional time and input from the entire project team. When the construction is completed, all functions within the control system must be tested and verified. Control actions must be initiated and monitored. All sensor readings must be checked and calibrated. The operation of all hardware and software must be tested. The entire system must be fully documented and maintenance personnel properly trained in its operation and maintenance.

Practice has shown that commissioning increases project first costs by between 2 and 5 percent, but money spent on commissioning is money well spent.

Lack of Training

Training operating and maintenance personnel is a basic requirement when control systems are installed or upgraded. No matter how sophisticated the system is, it will provide little benefit unless it is operated and maintained properly. Unfortunately, training is often ignored completely or else is added at the last minute once the installation has been completed.

Performing training activities as an afterthought — or simply assuming that on-the-job training is sufficient — shortchanges both the system operators and maintenance personnel, seriously reducing their ability to use the control system as fully as possible. Training programs must be included as a component of the control system installation project.

The training can be performed in-house or at an off-site location, but it must be a formalized program. System operators must receive training in how to perform basic system operations, as well as basic diagnostic functions. These are the front line people who will work with the system on a daily basis. They are the people who have the most immediate access to system operating information, information that will tell them if the system is operating properly or not. Recognizing system problems requires a certain level of situational awareness; operators must understand not only what is happening but why it is happening. And situational awareness can come only from experience built on a solid foundation of training.

Similarly, if the system is to be maintained by in-house personnel, those personnel must receive training specific to the control system installation. They will need to know how the system works, what each component does and why, where devices are located, how to perform system tests and how to interpret the results of those tests. And they will need to know how to operate the specialized equipment required in maintaining today’s control systems.

Racing the Clock

When problems occur in building systems, maintenance personnel are under pressure to get the systems back up and running as quickly as possible. Operations are being interrupted. Building occupants are uncomfortable and complaining. So it is not surprising that maintenance personnel push to make things better. But making things better is not always the same thing as fixing problems. All too often, solutions are implemented even though the problem hasn’t been fully diagnosed.

For example, when building occupants complain of inadequate air flow in a particular area, a common solution is to reset the damper. Similarly, outdoor air dampers are frequently closed to reduce humidity levels during the cooling season. While these solutions might improve conditions for those who are complaining, they are quick fixes that may create problems of their own. Resetting one damper may have little effect, but as more and more dampers are reset, the entire air balance of the building can be disrupted, resulting in widespread air flow problems. Similarly, closing outdoor air dampers will reduce humidity levels but will also reduce the amount of outdoor air being brought into the building, potentially causing indoor air quality problems.

Maintenance Overlooked

Building control systems require maintenance, both routine and preventive. These systems are complex and were never intended to be installed and forgotten, yet many facilities’ staffs do just that. Systems are ignored until problems occur. And when problems do occur, the lack of maintenance will help to mask the cause of the real problem, often resulting in maintenance personnel implementing fixes to non-existent problems. These fixes, in turn, only serve to further mask the real problem.

To keep systems in good operating condition, maintenance personnel must perform maintenance activities on a regular basis. At least once each year, all control points in the system should be verified in a process similar to that followed during the final stages of commissioning. All analog input and output devices should be tested and re-calibrated to correct for drift in sensor readings and wear in actuators. All digital input and output devices should be tested to verify proper operation and feedback.

Another important element in system maintenance is the updating of documentation. Buildings today are in a state of flux. Occupants are continually being moved. Functions being performed in the building change regularly. New equipment and activities are constantly being added. These changes require ongoing changes to the building’s HVAC system to meet the new needs of the occupants.

It is important that maintenance personnel update building documentation to reflect those changes, particularly when they involve the building’s control system. Unless documentation is kept up to date, it will be difficult to diagnose system problems in the future.

It’s not only maintenance personnel who must document changes in the building. Maintenance personnel too must have access to accurate, as-built drawings. Architects or contractors must update those each time modifications or additions are made to the building.

Turf Wars

There are a number of divisions of responsibility when it comes to operating a facility. For example, one unit within the organization may be responsible for the long-range planning of facilities. Another unit may manage construction and large-scale renovation projects. Operations are frequently separated from maintenance. And even maintenance can be subdivided into several groups, such as one for maintenance of the control system itself, another for building chillers and refrigeration equipment, and yet another for building HVAC systems.

While these divisions of responsibility are intended to take advantage of the benefits of specialization and to allow specific groups to focus on specific tasks, they unintentionally divide management of the facility into discrete groups, each with different goals and agendas. The result can be a series of turf wars among units that reduce the effectiveness of the organization and capabilities of the building’s systems.

Consider the conflicts that may exist just between the maintenance and construction units. One of the primary goals of the construction unit is to see that construction and renovation projects are completed on time and within budget. As a result, they are willing to make compromises in system design, selection, and installation that can result in long-term maintenance requirements.

Similarly, one of the primary goals of maintenance units is to reduce long-term maintenance costs and requirements. To accomplish this, they will lobby for the installation of specific components in systems that they believe are better suited to their requirements, regardless of first costs.

These conflicts can be particularly damaging to the operation of a building control system when different units within the maintenance department are called in to correct problems. Chiller mechanics might blame air conditioning problems on HVAC systems for inadequate air flow. HVAC system mechanics might blame chiller systems for those same problems on the basis of inadequate chilled water flow. And control system mechanics might blame everyone else, including building designers, saying that the systems are only doing what they were designed to do.

If facility executives are to make the most of today’s complex control systems, they must stop these turf wars. When problems occur, maintenance units must work together to diagnose and correct the problem. Construction personnel must work with both operations and maintenance personnel during the design and construction phases to see that both units’ objectives are met. Without this cooperation, no matter how smart the building and its systems are, it may appear quite dumb to the only people who really matter: the building occupants.


© 2001 Trade Press Publishing Corporation. By James Piper, PE, PhD, a consultant and writer with more than 25 years of experience in the facilities field. This feature courtesy Building Operating Management, a GreenBiz News Affiliate.