Managing Energy Efficiency

Definition: Energy efficiency is a measure of how well a system uses the available energy potential of its inputs. The goal of managing it is about using less energy to provide the same level of service, thus conserving our energy resources during production, operations, and disposal of systems. The impact goes beyond environmental concerns; it also has implications on the range of vehicles, the cost of operations, and the future of a system.

Keywords: efficiency, energy, green, life-cycle costs, trade-off

MITRE SE Roles and Expectations: MITRE systems engineers (SEs) are expected to be able to understand the impact of technical decisions on the energy efficiency of a system. They are expected to account for energy efficiency considerations across the system life cycle as part of the systems engineering process.

Background and Motivation

Many engineers have studied efficiency in the past and are familiar with the theoretical limits of a given thermodynamic cycle. Increased attention to energy efficiency has come about in the last 50 years, primarily as a result of a continuing trend of energy crises throughout the world. The first modern major crisis was in 1973. The oil crisis resulted not from a depletion of energy sources, but from political maneuvers that took the form of the Arab Oil Embargo. The effects were sharply felt throughout the country, and resulted in the price of oil quadrupling [1], rationing, and long lines. Other crises occurred in 1979, associated with the Iranian Revolution, and in 1990, over the Iraqi invasion of Kuwait. Several times during this century, price increases in oil were caused by reports of declining petroleum reserves, natural disasters such as Hurricane Katrina, political activities in other countries, and conflicts that did not directly involve the U.S. [2, 3]. Each of these demonstrates the importance of considering all elements of POET (political, operational, economic, technical), or as expanded, TEAPOT (technically accurate, economically feasible, actionable, politically and culturally insightful, operationally grounded, and timely) [4].

Complicating the landscape is the fact that most energy today is produced by non-renewable resources in the form of coal, fissile materials, petroleum, and natural gas. When production first begins with each material, the amount of material recovered for each unit of energy is large. For example, in the mid-nineteenth century when oil production began, the largest oil fields could recover 50 barrels of oil for every barrel used in extraction, refining, and transportation. Today that number is between one and five. Once it reaches one (one barrel of oil to make one barrel of oil), the only way to make the resource available for consumption is to use other energy sources to bring it to market. This situation will happen before the resource is physically exhausted.  Energy resource production follows nearly a bell-shaped curve called the Hubbert curve [5], and trails discovery by about 35 years. In the U.S., peak oil (the peak of the Hubbert curve) was reached in the 1970s and has resulted in the country importing increasing amounts as the consumption continued to increase since that time. For the world, peak oil is estimated to be 2020. As production falls, the production process gets more expensive and the price rises. The same happens for each natural resource. Understanding this sequence is important to understanding the push for increased energy efficiency.

The number of U.S. military bases overseas has declined over the past two decades, and it is getting increasingly difficult to gain access to countries to forward deploy forces and equipment. This trend and the desire for the U.S. military to minimize the risk to its forces have resulted in programs that deliver weapons systems that operate from longer ranges. To achieve this, either an increased infrastructure of resupply systems must be put in place, or weapons systems must be more efficient to achieve the longer ranges needed to accomplish the missions. As for the resupply chain, there is also a desire to reduce the forward footprint of deployed forces, including generators and the resupplied fuels (an issue now with complex weapon and computing systems and their power consumption).

Government Interest and Use. Energy efficiency is a parameter that can potentially be adjusted during the development of a system. It has a direct effect on the range of vehicles, as well as the upfront and recurring operating costs of systems. Secondary effects include minimum and maximum operating limits, and adverse affects on performance parameters like speed and dynamic control. In some domains, increased energy efficiency generally means higher upfront costs with the savings realized over the life cycle in the form of decreased energy bills.

The government uses energy to run its transportation fleets, surveillance and weapons delivery systems, facilities, and to information processing systems. Trends in data centers have shifted the predominate cost from the building itself to the operation of the building and, more specifically, to obtaining the energy. The Green Grid [6, 7] has established a simple set of metrics that can be used to reduce the energy consumption for the data center. While they are very simplistic, such as the ratio of power used by IT equipment to the power entering the facility, they give an indication of overall data center energy efficiency. Many organizations have used these measurements as the tool to reduce the cost of operations. These include Google, Mass Mutual, Patagonia, and Kimberly-Clark [8], [9, 10, 11, 12]. To date, more work in this area is being done in the commercial arena than in the government sector.

The government has established green standards for acquisitions, part of which mandate the use of Energy Star™ and EPEAT™ [13, 14, 15]. There has been an increased use of the U.S. Green Building Council LEED™ program in the acquisition of buildings. It is important to note that these buildings must be maintained and consistently improved to keep the energy efficiency of the building competitive. As with all green initiatives, the target continues to move over time [16, 17].

Best Practices and Lessons Learned

Be wary of advertised efficiency claims: Programs such as Energy Star™, EPEAT™, LEED™, and Green Globes (international counterpart to LEED™) need to be carefully scrutinized for how they gauge energy consumption. For example, a printer rated by Energy Star™ can be expected to achieve the stated energy efficiency only when operated in exactly the same manner in which the rating was obtained. Generally the test conditions used are not provided. So, there is the need to be aware of or find out what is being measured and how it applies to your system's situation [13, 14, 18, 19, 20, 21].

Know your system's operations: Thoroughly understand how the government intends to use the system before evaluating its energy consumption profile and requirements. Understand the level of energy management expertise in the contractor and the maintenance organization since, while components of a system may have energy saving modes, they may be shipped in a configuration that does not enable the modes. Also, look into whether operational, information security, or other policies or procedures prevent or impede their use [22]. As an example, in many organizations it is common practice to push out software updates during the early morning hours. If a system is in a low power mode, it may not respond to the push. To avoid this situation, an organization may have policies that prevent systems from entering a low power mode.

Take measures: The only way to truly know what the system is doing is to measure its performance. The more data you have, the greater your ability to make informed decisions about your system's operation, whether it be a weapons system, a building, or a data center. With more knowledge, the better you are able to know where and how energy is being used and recommend solutions to improve energy efficiency [16, 23, 24].

Involve all stakeholders: Energy efficiency is an enterprise level problem. In general, the organization paying for the energy is not the organization procuring the system or facility, nor the organization using or making decisions about using the energy. Be sure to involve all stakeholders [9, 17].

References & Resources

  1. CBC News in Depth, July 18, 2007, The Price of Oil, Marching to $100?, CBC News.
  2. Peter J. Cooper, July 8, 2006, "Record Oil Price sets the scene for $200 next year,",
  3. Mortished, Carl, August 30, 2005, "Hurricane Katrina whips oil price to a record high," The Times.
  4. The MITRE Corporation, CCG Quality Program, CEM Quality Handbook and Quality Tools.
  5. Grove, Noel, June 1974, “Oil, the Dwindling Treasure,” National Geographic.
  6. "Guidelines for Energy-Efficient Datacenters," The Green Grid, February 16, 2007.
  7. The Green Grid, viewed February 26, 2010.
  8. Anderson, Sean F., November 2009, "Improving Data Center Efficiency," World Energy Engineering Congress (WEEC).
  9. Belady, C., September 5, 2006, "How to Minimize Data Center Utility Bills," E-Business News.
  10. Dixon, Steve, November 2009, "Energy Management for Commercial Office Buildings: An Owner's Perspective," WEEC.
  11. McMahon, Jim, November 3, 2009, "Sustainable Distribution," Sustainable Facility.
  12. Marklein, B. Richard, and Juan Marin, November 2009, "Kimberly-Clark's Energy Management for 2015," WEEC.
  13. Bush, George W., January 24, 2007, Executive Order 13423, Strengthening Federal Environmental, Energy, and Transportation Management.
  14. Energy Star, viewed February 26, 2010.
  15. EPEAT, viewed February 26, 2010.
  16. Huppes, Gjalt and Masanobu Ishikawa, October 2005, "A Framework for Quantified Eco-efficiency Analysis," Journal of Industrial Ecology, vol. 9 no. 4, pp. 25–41.
  17. Myatt, Bruce, September/October 2009, "Low-Cost Data Center Energy Efficiency Programs in Action," Mission Critical, pp. 20–21.
  18. Boyd, Gale A, July 2005, "A Method for Measuring the Efficiency Gap between Average and Best Practice Energy Use, The ENERGY STAR Performance Indicator," Journal of Industrial Ecology, vol. 9 no. 3, pp. 51–65.
  19. DOE and EPA, Fuel Economy, (MPG and other information about vehicles), viewed February 26, 2010.
  20. Green Building Initiative, Green Globes: the practical building rating system, viewed February 26, 2010.
  21. U.S. Green Building Council (LEED), viewed February 26, 2010.
  22. Nordman, Bruce, Mary Ann Peitte, Kris Kinney, and Carrie Webber, January 1997, User Guide to Power Management in PCs and Monitors, Lawrence Berkeley National Laboratory.
  23. 80 PLUS Energy-Efficient Technology Solutions, February 26, 2010.
  24. Group, Jack, November 2009, "Success Stories in Cutting Facility Energy Costs Using Electric Submeters," WEEC.

Additional References & Resources

Rabiee, A., H. Shayanfar, N. Amjady, Jan-Feb 2009, "Reactive Power Pricing," IEEE Power and Energy Magazine, vol. 7, issue 1, pp. 18-32.

The MITRE Corporation, "Integrated Logistics Support," MITRE Systems Engineering Competency Model, viewed February 26, 2010.


Download the SEG

MITRE's Systems Engineering Guide

Download for EPUB
Download for Amazon Kindle
Download a PDF

Contact the SEG Team