Energy vs. labor
EMS provide savings in both energy and labor, and they provide critical information at the touch of a button — information that previously might have taken days for one person to accumulate. EMS provides timely reports and red-flags anomalies in HVAC operation data. It checks programmed schedules against temporary overrides and corrects the equipment schedule when necessary. In short, the system can save a great deal of energy.
But the system can’t replace a maintenance person going out into buildings taking air and machine temperatures and checking damper positions. On top of that, the EMS isn’t connected to older HVAC equipment — the systems that tend to have more problems.
Cutting waste
Using staff to find inefficiencies in the HVAC system might sound like a waste but not as much of a waste as inefficient system operation. Almost any facility that doesn’t do what we’re talking about is wasting 10-20 percent of their HVAC energy, mostly due to equipment that is doing more than it has to.
While many facilities take steps to head off building occupant complaints and premature mechanical failures of HVAC systems, their efforts often stop there. Little of that same zeal is given to efforts to fix operations that are energy inefficient.
One simple rule underlies the audit process: Get the HVAC equipment to do what it is supposed to do and nothing more. An audit is not surgery or rocket science.
We have found conditions in facilities that are obvious but overlooked and that can add up to significant wastes of energy. Often, maintenance staff can find and fix these conditions if their responsibilities are focused at least in part on energy efficiency.
Many maintenance staff have proven their abilities to keep facilities — even poorly designed facilities — running. It’s not the lack of ability. It’s the lack of focus and organization, a road map.
Deductive process
We ask managers to start the audit process by targeting the largest energy users, such as dampers, chillers, boilers, motors and pumps, since even small gains related to these components can yield significant energy savings. But before personnel actually check a piece of equipment, it is important to do a little research. How much energy does a piece of equipment need? And how much energy is it using?
Inspectors should start with the large and simple and work toward the small and complex, collecting utility bills, as well as actual use data. All of this information will help in determining whether or not a problem exists. Air-handling units are a case in point. Fan motors are major energy users, but how often are air-handling units checked against actual, scheduled need? Is the unit turning on and off according to actual space use?
Even facilities that have been recognized for their energy savings find that continual improvement via regular audits is necessary. You are going to have one or two air handlers with problems that software doesn’t tell you about on any big facility at any one time.
A focus on balance
Of particular importance in auditing large systems are a full-time contracted worker who serves as air and water system balancer and a full-time staff energy officer. And because the balancer gets his marching orders from the maintenance department and relieves maintenance of many headaches, he is a welcome team member.
The balancer makes sure systems provide the required level of comfort. As a result of this strategy, we can back off on schedules or fan speeds without affecting comfort, and the facility saves energy and money.
Facilities managers and staff must make a conscious effort, however, to reduce energy use. No one can assume that systems are running correctly just because no problems are evident.
Air-handling units are designed to operate most efficiently on the hottest days of the year when facilities need maximum air flow. During the winter, a space probably needs one-half that amount of air flow. If the temperature sensor is satisfied, managers might think air-handling units are working efficiently then, too. But that might not be the case. The operation of the HVAC system shouldn’t be a static thing. Building use changes over time. It’s important to regularly check the system to make sure that it reflects the change in use.
Selecting Audit Targets
A regular audit focusing just on energy efficiency would be best. Items to consider in developing an audit are these:
- operation schedules vs. space use
- damper operation
- motor voltage and current
- temperatures and pressures for chillers and cooling towers
- supply- and mixed-air temperatures
- simultaneous heating and cooling
A periodic HVAC system audit need not be an extensive investigation. The biggest energy users should be the highest priority, and auditors should first check the most obvious problems, such as equipment schedules. Most other operations can be included in PM schedules, and others can be done during routine maintenance.
