HVAC: Taking Control of Energy Savings
By James Piper February 2007 - Energy Efficiency
Building control systems function as the central nervous system for facilities. Engineering and maintenance managers can use a well-designed and installed system to perform a range of activities that improve the operating efficiency of the building, while enhancing comfort and security.
But if the system is in adequate, outmoded or improperly used, it can turn even the most efficient HVAC systems into a disaster.
One of the most cost effective measures for improving operations is updating a poorly performing control system. But having an inadequate existing control system is only one reason for upgrading. Rapid advances in the development of standards and technology have combined to create a new generation of control systems that offer capabilities that go far beyond those available just a few years ago.
Most existing control systems only automate a portion of the building’s energy-using systems. Some focus solely on the central equipment, ignoring up to 90 percent of the energy-using equipment installed in a building. While this might have been a good practice when the system was installed, advances in system design accompanied by reduced installation costs and increased energy costs now make it important to integrate as many functions as possible.
For these reasons, a number of managers now are looking to upgrade their building control systems to give them the ability to better monitor and operate their facilities.
One of the most important factors in being able to minimize energy use in a facility is thoroughly understanding how the facility uses energy, when it uses it, and where it goes. Without this information, managers will not have the information they need to establish control over energy use. Building control systems can easily give them that information, and more.
In its most basic form, a system taps into the utility’s meter systems serving the facility, or technicians can install additional, dedicated meters. For electricity, the meters collect data on kilowatt hour use and peak demand. They also can collect similar information for other utilities. For multiple facilities, the software can be combined with internet connections to gather and record data for all facilities.
But the systems can do much more than simply record utility-meter data. Collecting accurate data quickly is only the first step. The systems also serve as a very effective tool in analyzing that data. They provide a system for checking the accuracy of utility bills. As a database of energy use grows, managers can use it to identify new opportunities that reduce energy use and cost.
By providing a real-time flow of information, the systems enable managers to monitor the energy and cost impact of implemented measures. Accurate reporting gives managers the information they need to analyze energy use trends. When faced with alternatives for operations, managers can use data from the system to make energy-efficient decisions. The systems also can provide the information needed to justify costs for energy-management projects. They can quantify savings that implemented measures generate.
Technicians also can install meters throughout a facility to monitor energy use at the building or system level. This does not require large investments in hardware, and the benefits from the system will help change a passive energy-management program into an active one.
Not all control systems are equal. The same control system installed in two different facilities might have vastly different capabilities. For those reasons, it is critical that managers become active participants in the project team from the beginning. Designers will only design and installers will only install what has been specified.
Without the involvement of managers in the design process, other parties tend to overlook elements important to the operation of the facility. And adding those elements later generally will cost several orders of magnitude more than if planners had included them in the first place.
Managers are in a unique position when it comes to contributing to the design process because they know the operations of the facility the best. They know the location of current problems are, as well as the best course of action to correct them. If the existing control system is inadequate, they know why and what should be done to overcome those inadequacies. Their involvement can ensure that the system installed is neither a generic offering from a system manufacturer, nor one that is overdesigned with features that those using the system do not need and will not use.
Managers can start by identifying all functions the system must perform, as well as all systems and components that will connect to the new control system. Failing to do so will result in system designers making judgments about what is not important to include in the new system.
Managers also must act as a reality check on system proposals for the facility. Planners have hundreds of systems to choose from, and thousands of variations of those systems, so it is the manager’s duty managers to determine which system best meets the needs of the facility.
An essential task to ensure the success of the system is identifying staffing requirements. It is a popular misconception that upgrading a building control system reduces staffing requirements. While the systems will save energy and reduce overall maintenance costs, its users can expect to need a larger staff.
The department will need more staff to operate and maintain the system, and the additional staff most likely will have to correct control deficiencies the new system identifies.
Managers need to examine the tasks that are being performed by their staff under the current control system and see how those tasks will expand or change under the new system. Once the system is complete is no time to look for any additional staffing.
This staffing process must start as soon as possible. In most cases, managers require a long lead time for finding and hiring qualified people to work with the new system. Those people also should be available to assist in overseeing the system’s installation.
Another important task that often goes overlooked is training. Any specification developed for a new control system must cover training requirements. It must identify the level of training, the number of people who will receive training at each level, who will conduct the training, where it will occur, and when it will take place.
All control system installation projects should include a thorough commissioning. This process should start with a complete point-by-point check of all control devices that have been installed or connected to the system. All devices must pass a functional and performance verification to insure they are operating as intended and are working together properly. Inspectors should test all sensors and verified proper calibration. They also should sequence and verify all control programs.
Skipping the commissioning process on the assumption that the system is self checking will only increase in troubleshooting costs over the life of the system. As a rule, managers can expect a system that has passed the commissioning process to produce energy savings that are at least 20 percent greater than those for a system for which commissioning was bypassed.
Even commissioning is complete, managers need to ensure that the system continues to operate as intended. Managers should expect that with time, sensors will go out of calibration, controllers will fail, and unintended modifications will be made to the equipment being controlled. Unless managers identify and address these modifications and problems when they occur, system performance will slowly decline.
Field technicians and system operators also should verify all system points once annually. As part of this verification process, they should verify sensor readings. Although this is a time-consuming process, it is necessary if these systems are to provide the level of service and the rate of return expected.
It is also critical to keep all system documentation current. When the system is completed, documentation should be turned over to system managers. Without that documentation, it will become more and more difficult to keep the system operating at its peak efficiency.
James Piper, P.E., Ph. D., is a national facilities consultant based in Bowie, Md.
The Controls Group North America (CGNA) is a national network of independent HVAC/R controls distributors. Established in 1983, CGNA has 35 members with 130 locations nationwide and more than 74,000 customers, forming the largest network of independent controls distributors in the nation. CGNA provides marketing programs, services and business opportunities to give their members and preferred vendors a competitive advantage for local, regional and national accounts.