A building tune-up also includes a review of HVAC and lighting systems' time/set-point schedules, which are programmed into the EMS. During an initial EMS installation, it is not uncommon for an EMS contractor to set HVAC and lighting schedules to run continuously, leaving fine-tuning to the owner.

Meeting with facility representatives is the best way to determine optimal time schedules. A list of HVAC and lighting controls, as well as color-coded floor plans that highlight coverage areas, also is helpful. The resulting time/set-point schedules for a large campus facility should be kept in a database. To prevent inaccurate time/set-point adjustments, some EMSs automatically reset settings daily.

EMS AUDIT

An EMS audit is a detailed evaluation of an EMS's operation. Even the best EMS will experience control-equipment failures over time. Building owners should have a strategy to routinely check for such failures. Typical EMS failures include:

• Indication of a chilled-water valve being “closed,” but display of a cold supply-air temperature, which suggests the valve is not closing.

• Indication of a hot-water valve being “closed,” but display of a warm supply-air temperature, which suggests the valve is not closing.

• Instruction that fans be off, but indication that fans are on.

• Temperature- and humidity-sensor readings that appear to be out of range, which suggests a sensor defect.

• The forcing of EMS points to manual, rather than automatic, control, which frequently suggests an operational or maintenance deficiency.

• Display improper space or supply-air temperature settings, which suggests the set points differ significantly from typical settings.

• Display occupancy-schedule settings that differ from similar spaces or units in the building.

• Trimming/offsetting of space or supply-air temperature sensors that forces the HVAC system to supply additional heating/cooling when none is required.

• Display duct static pressures significantly higher/lower than the air-handling unit's static-pressure set points, which suggests fan, belt, or airflow issues.

• Display of very high or low space temperatures in spite of reasonable discharge-air temperatures, which often indicates deficient airflow or incorrect minimum settings.

• Failure to communicate with equipment controllers.

• Display of discrepancies between a damper's open/closed position and actual airflow.

Finding these kinds of problems can be simple: Search for discrepancies on a graphical display of the EMS's HVAC system. For example, the EMS display in Figure 1 shows a closed chilled-water valve and a supply-air sensor's low-temperature reading. Therefore, it is likely that the chilled-water valve is not closing properly. Obviously, this scenario includes a lot of energy waste, and immediate maintenance is necessary.

Once an EMS failure is identified, it is added to a summary spreadsheet. This spreadsheet makes issues easier to find, correct, and track. For each issue, a spreadsheet should contain:

• A description of the issue and the action required to resolve it.

• An identification number/point name for the effected equipment's controller and system.

• A description of the effected system.

• The issue's location, such as division, area, and/or building.

• The date the issue was discovered.

• The type of issue, such as problems with humidity, time/set-point schedules, pressure, variable-frequency drives, temperature, and chilled-/hot-water valves.

• The issue's priority, such as high, medium, or low.

• Any relevant values, such as temperature, humidity, pressure, fan status, etc.

A spreadsheet can be sorted by any of these criteria. This offers facility personnel a flexible tool that can help them maintain and repair equipment and controls. Also, it serves as a checklist that later can be reviewed to determine if appropriate repairs have been made or a system modification is needed.

An EMS audit should be followed by a field evaluation that investigates opportunities to reduce energy waste.

EMS ALARMS

An EMS can be programmed to send out an alarm when problems occur. If properly managed, these alarms can provide timely information to a maintenance department, allowing it to respond quickly. However, because their large volume can be overwhelming, critical alarms should be prioritized. High-priority alarms should be sent immediately via text message to lead maintenance personnel. For example, a high-temperature alarm for a chilled-water system would indicate a problem with a chiller, chilled-water pump, or cooling tower requiring immediate attention.

Another set of alarms can notify an owner of diagnostic issues. Because they can be large in number, these second-tier alarms can be used as the basis of a daily report summarizing all EMS failures requiring attention. The report can be sent via e-mail to the appropriate parties.

CONCLUSION

Energy savings starts during the design phase. A building tune-up can help fine-tune an EMS for optimal performance. With a thorough understanding of a facility's operating requirements, optimal HVAC- and lighting-system time/set-point schedules can be established. An EMS audit is more detailed, involving the study of the operation of HVAC and lighting systems for the identification and timely correction of problems. The results of these efforts are the proverbial “low-hanging fruit” on which energy managers should be focused.

ABOUT THE AUTHORS

Paul J. Allen, PE, is the chief energy-management engineer for Reedy Creek Energy Services (RCES), a division of Walt Disney World Co. He is responsible for the development and implementation of energy-conservation projects throughout the Walt Disney World Resort.

Michael J. Brennan, PE, CEM, LEED AP, is an energy-management engineer for RCES and responsible for conducting energy assessments to identify opportunities that reduce energy consumption within the Walt Disney World Resort.