Best Practice in Building Maintenance. Reactive, Preventative or Predictive?

The US Department of Energy publication, Operations & Maintenance Best Practices, A Guide to Achieving Operational Efficiency (G. P. Sullivan, R. Pugh, A. P. Melendez, W. D. Hunt, December 2002) highlights O&M programs targeting energy efficiency that are estimated to save 5% to 20% on energy bills without a significant capital investment.

The introduction to this guide states

Effective O&M is one of the most cost-effective methods for ensuring reliability, safety, and energy efficiency. Inadequate maintenance of energy-using systems is a major cause of energy waste in both the Federal government and the private sector. Energy losses from steam, water and air leaks, uninsulated lines, maladjusted or inoperable controls, and other losses from poor maintenance are often considerable. Good maintenance practices can generate substantial energy savings and should be considered a resource. Moreover, improvements to facility maintenance programs can often be accomplished immediately and at a relatively low cost.

What is effective O&M? The authors refer to work by Piotrowski (2001) who compares four different maintenance plans for pumps:

Reactive Maintenance (Breakdown or Run-to-Failure Maintenance)
Basic philosophy
• Allow machinery to run to failure.
• Repair or replace damaged equipment when obvious problems occur.
Cost: $18/hp/yr
This maintenance philosophy allows machinery to run to failure, providing for the repair or replacement of damaged equipment only when obvious problems occur. Studies have shown that the costs to operate in this fashion are about $18 per horsepower (hp) per year. The advantages of this approach are that it works well if equipment shutdowns do not affect production and if labor and material costs do not matter.

Preventive Maintenance (Time-Based Maintenance)
Basic philosophy
• Schedule maintenance activities at predetermined time intervals.
• Repair or replace damaged equipment before obvious problems occur.
Cost: $13/hp/yr

This philosophy entails the scheduling of maintenance activities at predetermined time intervals, where damaged equipment is repaired or replaced before obvious problems occur. When it is done correctly, studies have shown the costs of operating in this fashion to be about $13 per hp per year. The advantages of this approach are that it works well for equipment that does not run continuously, and with personnel who have enough knowledge, skills, and time to perform the preventive maintenance work.

Predictive Maintenance (Condition-Based Maintenance)
Basic philosophy
• Schedule maintenance activities when mechanical or operational conditions warrant.
• Repair or replace damaged equipment before obvious problems occur.
Cost: $9/hp/yr
This philosophy consists of scheduling maintenance activities only if and when mechanical or operational conditions warrant-by periodically monitoring the machinery for excessive vibration, temperature and/or lubrication degradation, or by observing any other unhealthy trends that occur over time. When the condition gets to a predetermined unacceptable level, the equipment is shut down to repair or replace damaged components so as to prevent a more costly failure from occurring. In other words, “Don’t fix what is not broke.” Studies have shown that when it is done correctly, the costs to operate in this fashion are about $9 per hp per year. Advantages of this approach are that it works very well if personnel have adequate knowledge, skills, and time to perform the predictive maintenance work, and that it allows equipment repairs to be scheduled in an orderly fashion. It also provides some lead-time to purchase materials for the necessary repairs, reducing the need for a high parts inventory. Since maintenance work is only performed when it is needed, there is likely to be an increase in production capacity.

Reliability Centered Maintenance (Pro-Active or Prevention Maintenance)
Basic philosophy
•­ Utilizes predictive/preventive maintenance techniques with root cause failure analysis to detect and pinpoint the precise problems, combined with advanced installation and repair techniques, including potential equipment redesign or modification to avoid or eliminate problems from occurring.
Cost: $6/hp/yr
This philosophy utilizes all of the previously discussed predictive/preventive maintenance techniques, in concert with root cause failure analysis. This not only detects and pinpoints precise problems that occur, but ensures that advanced installation and repair techniques are performed, including potential equipment redesign or modification, thus helping to avoid problems or keep them from occurring. According to studies, when it is done correctly, operating in this fashion costs about $6 per hp per year. One advantage to this approach is that it works extremely well if personnel have the knowledge, skills, and time to perform all of the required activities. As with the predictive-based pro- gram, equipment repairs can be scheduled in an orderly fashion, but additional improvement efforts also can be undertaken to reduce or eliminate potential problems from repeatedly occurring. Further- more, it allows lead-time to purchase materials for necessary repairs, thus reducing the need for a high parts inventory. Since maintenance work is performed only when it is needed, and extra efforts are put forth to thoroughly investigate the cause of the failure and determine ways to improve machinery reliability, there can be a substantial increase in production capacity.

Where are you operational and maintenance practices in the continuum of O&M practices? If you rely on reactive maintenance, then consider the double benefits of reduced operating costs and reduced energy costs, as motivation to move toward proactive maintenance.

Remember, you can’t manage what you don’t measure, and an effective CFMS system with key operational performance indicators will help you measure your progress through your journey.