Operations & Maintenance Best Practices: A Guide to Achieving Operational Efficiency, Release 3.0 (August 2010)

Overview

The guide estimates that energy-focused O&M programs can save 5% to 20% of energy bills without significant capital investment, and argues that low-cost or no-cost O&M measures should be considered before capital energy conservation measures. Reasons: most measures can be done by in-house staff, have immediate payback and need no design and bid process. If an energy savings performance contract (ESPC) is being considered, some retrocommissioning beforehand is advised, with the contractor informed, otherwise baselines may be inaccurate.

The maintenance chapter compares reactive, preventive, predictive and reliability-centered maintenance (RCM). More than 55% of maintenance resources at an average facility still go to reactive work (31% preventive, 12% predictive). Preventive maintenance is estimated to save 12% to 18% over reactive, and predictive 8% to 12% over preventive alone, with about 10x ROI, 25-30% lower maintenance cost, 70-75% fewer breakdowns and 35-45% less downtime. Top-performing facilities use under 10% reactive, 25-35% preventive and 45-55% predictive. Annual cost per horsepower is $18 for reactive, $13 preventive, $9 predictive and $6 for RCM.

The predictive technologies chapter covers thermography, lubricant and wear particle analysis, ultrasonic analysis, vibration analysis, motor analysis and performance trending. The commissioning chapter covers the process, typical findings and benefit tracking. The metering chapter stresses that meters are not an efficiency technology but data sources, with uses such as bill verification, cost allocation, demand response, measurement and verification, benchmarking and spotting opportunities, and that advanced meters should record at least hourly interval data. Chapters 3 and 4 cover O&M management, contracting and the computerized maintenance management system.

The equipment chapter gives checklists and savings calculations for boilers, steam traps, chillers, cooling towers, energy management and building automation systems, air handling, fans, pumps, motors, air compressors and lighting. On chillers, raising chilled water temperature 2-3 °F on a centrifugal chiller can raise system efficiency by 3% to 5%, and lowering condenser water temperature 2-3 °F by 2% to 3%. A poorly maintained cooling tower raises condenser temperature, and a chiller uses 2.5% to 3.5% more energy for each degree of increase. Boiler combustion tuning can save 2% to 20% fuel.

The guide is not data-center specific; it was written for federal buildings, Release 3.0 dates from August 2010, and the executive orders and targets it cites (such as EO 13514 and DOE Order 430.2B) belong to that period. Savings percentages are U.S. estimates and vary by site. The most useful parts for data center teams are maintenance strategy selection, the priority matrix, metering planning and chiller and tower operating practice. The final chapter offers a ten-step roadmap from management awareness to a first operational efficiency project and then to the next piece of equipment.

Key points

1. Energy-focused O&M programs are estimated to save 5% to 20% of energy bills without significant capital investment.
2. More than 55% of maintenance resources at an average facility are still spent on reactive maintenance (31% preventive, 12% predictive).
3. Preventive maintenance is estimated to save 12% to 18% over reactive maintenance.
4. Predictive maintenance is estimated to save 8% to 12% over preventive-only programs, with about 10x ROI, 25-30% lower maintenance cost, 70-75% fewer breakdowns and 35-45% less downtime.
5. Top-performing facilities use under 10% reactive, 25% to 35% preventive and 45% to 55% predictive maintenance.
6. Annual maintenance cost per horsepower: $18 reactive, $13 preventive, $9 predictive, $6 RCM.
7. On a centrifugal chiller, raising chilled water temperature by 2-3 °F can increase system efficiency by 3% to 5%, and lowering condenser water temperature by 2-3 °F by 2% to 3%.
8. A chiller uses 2.5% to 3.5% more energy for each degree increase in condenser temperature, and cooling tower neglect is a leading cause.
9. Boiler combustion tuning and related O&M can yield fuel savings of 2% to 20%.
10. Advanced meters should record at least hourly interval data and send it to a remote location; meters are data sources, not efficiency technologies in themselves.

Using it in design

• Choose maintenance strategy by equipment criticality: predictive for critical equipment with random failures, preventive for equipment subject to wear, reactive for small non-critical items; build a master equipment list and priority matrix.
• Plan measurement points and access for predictive techniques such as thermography, vibration, oil and ultrasonic analysis at design stage.
• In the chiller plant set the highest practical chilled water temperature and lowest practical condenser water temperature as operating goals; with a 2-5% efficiency effect per 2-3 °F, write setpoint optimisation into operating procedures.
• Include cooling tower maintenance (fouling and scale, water distribution, blowdown and concentration, fan start frequency, safe access) in the maintenance programme and contract, and calculate the energy cost of each degree of lost condenser temperature.
• Plan metering early: sub-meters, hourly or finer interval data, central monitoring, and requirements for bill verification, cost allocation and measurement and verification.
• Specify commissioning and retrocommissioning for new and existing equipment together; responsibility gaps often arise at control system interfaces.

Who should read it

Energy and facility managers, maintenance engineers and operations teams who establish building O&M programmes, including for data centers.

Document contents

1. Chapter 1 - Introduction and Overview
2. Chapter 2 - Why O&M?
3. Chapter 3 - O&M Management
4. Chapter 4 - Computerized Maintenance Management System
5. Chapter 5 - Types of Maintenance Programs
6. Chapter 6 - Predictive Maintenance Technologies
7. Chapter 7 - Commissioning Existing Buildings
8. Chapter 8 - Metering for Operations and Maintenance
9. Chapter 9 - O&M Ideas for Major Equipment Types
10. Boilers and Steam Traps
11. Chillers
12. Cooling Towers
13. Energy Management/Building Automation Systems and Air Handling Systems
14. Fans, Pumps, Motors, Air Compressors and Lighting
15. Chapter 10 - O&M Frontiers
16. Chapter 11 - Ten Steps to Operational Efficiency
17. Appendix A - Glossary of Common Terms

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Publication details

Authors

G. P. Sullivan; R. Pugh; A. P. Melendez; W. D. Hunt

Publisher

U.S. DOE FEMP

Year

2010

Document language

English

Source type

Government / public

Access

Open licence — downloadable

Licence

U.S. public domain — U.S. Government work; free to reuse

Licence evidence

www.energy.gov

Citation