Operations & Maintenance

Best Practices for Energy Management

O&M Energy Management Guide

Reactive, Proactive, and Predictive Maintenance

A critical component of O&M efficiency is identifying the best maintenance approach to suit the property’s needs. The Northwest Energy Efficiency Alliance’s BetterBricks program describes maintenance strategic planning as follows: 

There are three general approaches to maintenance management: reactive, preventive, and predictive. Evaluate the current approach and adopt a maintenance strategy that best supports the long-term O&M plan. 

  • Reactive. This is the "run it until it breaks" approach. In the short run, this saves staff time and expense but over time it is costly in terms of unplanned equipment downtime, repairs, and shorter equipment life. 

  • Preventive. Preventive maintenance (PM) occurs at time intervals or at run-hour milestones. Because most HVAC equipment is capital intensive, this is more cost-effective than reactive maintenance. 

  • Predictive. This approach uses periodic measurements to detect evidence that machinery is deteriorating, with the aim of extending service life by avoiding impending problems. Special diagnostic equipment, which requires additional staff training, is needed, but it will maximize equipment life and efficiency. 

Most organizations use a combination of reactive and preventive maintenance with or without maintenance-service contractors. Generally, the most cost-effective solution is a combination of preventive and predictive maintenance that appropriately balances prevention and repair. 

Machines and systems will still stop working at times, so reactive maintenance will always be a necessity. However, the proactive approaches of preventative and predictive maintenance improve building efficiency and reduce costs, both in terms of energy consumption and the cost of downed equipment. 

 

Preventative Maintenance 

The backbone of a preventative maintenance strategy is essentially a checklist. It may come in virtual form through the CMMS or be a simple hard copy, but a checklist of preventative maintenance procedures remains essential.

    • Fans (Supply, Exhaust, Return)(Belt or Shaft Driven) 

    • Variable Air Volume Terminal Units 

    • Heating and Ventilation Units 

    • Unit Heaters 

    • Pumps 

    • Heat Exchanger 

    • Cabinet Unit Heaters 

    •  Unit Ventilators 

    •  Packaged Units 

    •  Steam-Powered Domestic Hot Water Heater 

    •  Pressure Reducing Valves 

    • Split System Air Conditioners 

    •  Window Air Conditioning Units 

    • Air Compressors 

    • Air Dryers 

    • Expansion Tanks 

    • Absorption Chillers 

    • Centrifugal Water-Cooled Chillers 

    • Reciprocating Air-Cooled Chillers 

    • Cooling Towers 

    • Gas-Fired Domestic Hot Water Heater 

    • Vacuum Pump Units 

    • Steam Boilers 

    • Water Boilers 

    • Submersible Pumps (Sump/Ejector) 

    • Steam Radiators 

    • Steam Traps 

    • Emergency Diesel Generator 

Predictive and Condition-Based Maintenance

The CMMS software of today often incorporate predictive maintenance into their general platform or additional predictive maintenance software can be integrated within the CMMS. Organizations will want to analyze the systems and machines on their properties to assess their need for predictive maintenance and then employ conditions-based monitoring practices where needed throughout the building.  

A CMMS provider describes “condition-based monitoring” as follows: 

Condition-based monitoring is a key step in the process and it works on the assumption that all machines will deteriorate and fail partially or fully at some point. Therefore, the goal is to preempt these failures by placing various monitoring sensors on the assets. From there, the data is collected, analyzed, and used to create predictive failure algorithms, which inform your maintenance actions. 


There are a wide variety of sensors available including (but not limited to): 

  • Thermometers 

  • Tachometers 

  • Endoscopes 

  • Thermal cameras 

  • Leak detectors 

  • Accelerometers 

Notably, an organization could simply employ a condition-based maintenance plan, compared to a full predictive maintenance plan. Condition-based maintenance remains superior to only preventative and reactive maintenance, but it only provides data on the condition of various assets whereas predictive maintenance analyzes the data to create predictive algorithms.