Operation and Maintenance Best Practices for Energy-Efficient Buildings
Tune It Up, Turn It Off, And Check It Out
When you integrate energy efficiency into your facility’s operation and maintenance (O&M) program, you can reduce energy use without significant capital investment. In addition, efficient O&M strategies:
- Reduce operating costs
- Reduce the risk of early equipment failure and unscheduled down time
- Increase a facility’s net operating income (NOI)
- Maintain comfort, leading to fewer “hot and cold” complaints
To keep expensive building equipment operating efficiently, make sure to tune it up, turn it off, and check it out.
That is, building equipment and systems should be appropriately calibrated and tuned to run as efficiently as possible, scheduled to run only as needed, and periodically checked to prevent performance drift.
Tune It Up
Assess your current O&M practices, implement the identified tune-ups, and document your actions, then track savings to finance future energy-efficiency work:
- Assess. A rigorous O&M tune-up requires performing a thorough assessment of the current operation and maintenance practices. It systematically looks at all aspects of the current O&M program, and may include spot testing equipment and controls, checking pressures, temperatures, power, flows, and lighting use over time, and reviewing schedules and control strategies to determine whether the building is being operated optimally. For the assessment to be successful, O&M staff need to view the process as a means of enhancing and supporting their work and not as a fault-finding activity.
- Implement. Savings can only accrue if recommendations from the assessment are implemented. Once the improvements are selected and prioritized, many of them may be implemented very quickly and inexpensively. For example, control strategy or schedule improvements, where the greatest savings often occur, may only take a few hours to implement.
- Document. Documenting the sequence of operation and energy-efficient control strategies for the energy-using systems is essential to understanding building control. The control documentation is critical for maintaining energy-efficient operation and effectively troubleshooting operational problems. Once accurate building documentation is obtained, keep it updated to maintain continuity. For example, sensor set-point changes, sensor location changes, and control strategy changes should be documented whenever they occur. If the changes remain in the heads of only one or two staff members, when they leave the organization the information is lost. Relying on memory can lead to mistakes that cost time and energy.
- Track savings. The O&M tune-up activities may be the first step in developing a sustainable finance mechanism for the organization. Once an organization funds the initial O&M assessment and tune-up improvements, future energy efficiency work can be funded from the savings generated by the low-cost O&M improvements. This kind of sustainable finance mechanism requires monitoring and tracking savings so that they can be dedicated to future improvements.
Turn It Off
Optimize efficient operation with automatic controls and scheduling:
- Operate equipment only when needed. The number one way to waste energy is to leave equipment and lights on when they could be off. The payback for improved scheduling is almost immediate. Although individual pieces of equipment may be well maintained and perform efficiently, unless the control strategies and occupant needs are periodically reviewed, equipment may be operating more than necessary. Because many people often have access to lighting and HVAC controls, parameters and schedules may be changed to meet a special need or unusual condition and never get changed back to their original setting unless preventive maintenance procedures for addressing operational issues are in place.
- Maximize the use of the control system. Although many facilities have sophisticated, computerized, energy management systems (EMS) in place, most do not take full advantage of the systems’ capabilities. Staff often use these systems only to turn equipment on and off. These systems can be programmed to accomplish control strategies such as optimal start/stop, air- and water-side economizing, chilled and heating water resets, night setback and setup, night purge, morning warm-up, hot and cold deck optimization, and lighting sweeps. These strategies can save energy dollars beyond ordinary time-of-day control. Newer HVAC equipment may also have sophisticated integral controls that can be programmed to accomplish energy-efficient strategies such as chilled water reset. These integral controls should be programmed and adjusted to take full advantage of energy-efficient strategies.
Equipment may operate very efficiently, but if it’s “on” when “nobody’s home,” the only thing happening is energy waste.
Check It Out
Typically, the primary goal of the preventive maintenance (PM) plan is reliability and increased equipment life. Buildings often have extensive PM plans, which are rigorously carried out by the O&M staff. However, even if a piece of equipment or a system is meticulously maintained, if it is poorly operated using inadequate control strategies or improper scheduling, vast amounts of energy waste can occur. Also, poor equipment operation can lead to premature equipment failure (for example, short-cycling) and an increase in maintenance requirements. Rather than focusing on component-by-component care, O&M plans should be balanced to address the operation part of O&M as equal in importance to maintenance.
Redefine preventive maintenance to include activities critical to energy-efficient building operation:
- Perform periodic reviews. As part of preventive O&M planning, perform periodic reviews of HVAC and lighting schedules, temperature setpoints, and occupant/tenant use requirements to ensure that equipment runs only when needed. Develop procedures to periodically review and monitor EMS time-of-day schedules, optimum start/stop strategies, temperature setups and setback, lock-outs, freeze protection, and other strategies and parameters that stage or turn equipment on and off. Also review and monitor any other on/off controls such as programmable and mechanical time clock settings, integral equipment controls, lighting photocells, sweeps, and occupancy sensors for proper operation.
- Schedule after-hours walk-throughs. A quick walk through the building after hours can be quite revealing. For buildings where equipment should be OFF after hours, managers can detect stray equipment operation by simply entering the building during unoccupied hours and listening for unexpected noise. Building staff should perform an after-hours walk-through once every six months to observe the behavior of heating and cooling equipment, lighting, and office equipment such as copiers, printers, and computers. Alternatively, staff can use portable dataloggers at the electric panels to track whether equipment is ON when it should not be.
- Seasonally adjust control strategies. Just as certain maintenance tasks are performed to prepare equipment for heating or cooling season, control strategies should also be reviewed and adjusted. A good control strategy for cooling season is not necessarily optimal for “swing” season or heating season.
- Track performance over time. Develop O&M procedures and forms for tracking actual equipment performance against expected performance. Forms may include the task description, checking method and frequency for each piece of equipment, reporting formats, procedures for addressing non-conformance issues and how to resolve performance deficiencies. In many cases the data gathering procedures on equipment performance dovetail nicely with other PM work adding very little staff time for accomplishing the task
At first glance, this list may appear to increase the workload of O&M staff. However, performing these tasks on a regular, proactive basis should actually save staff time in the long run, because preventive maintenance helps to reduce equipment malfunction and occupant complaints. Staff who spend more time on preventive operations generally spend less time “fighting fires” and troubleshooting operational problems.
By redefining the preventive maintenance program to include operational activities that are critical to energy-efficient building operation, you can help ensure that this efficient performance will continue over time.