Identification of significant energy uses (SEUs) is necessary for your organization to achieve the most improvement in performance with the fewest available resources. There are seven tasks associated with determining SEUs:

• 2.5.1 Prepare a list of equipment and systems
• 2.5.2 Develop an energy balance
• 2.5.3 Determine and apply criteria for significance
• 2.5.4 Identify relevant variables affecting SEUs
• 2.5.5 Determine current energy performance and implement monitoring
• 2.5.6 Calculate future energy use and consumption
• 2.5.7 Plan for updating the SEUs

The management representative, assisted by the energy team, typically establishes and applies criteria for determining the organization’s SEUs. At a minimum, this involves deciding on criteria for “substantial energy consumption” and “considerable opportunity for improvement.” The method used to determine the SEUs must be documented. Because SEUs must be managed through operational controls, training, and monitoring and measurement, designating an energy use as significant should be decided upon carefully.

2.5.1 Prepare a list of equipment and systems

In Steps 2.2.2 and 2.2.3, you identified your organization’s energy uses and data needs as a first step in understanding your organization’s energy equipment, systems and processes and identifying SEUs. The energy data collection process established in Step 2.3 and the energy consumption analysis that was discussed in Step 2.4.2 is also a precursor to identifying SEUs. The next step is to break down the energy uses you have identified and determine the energy they consume. To do this, gather detailed information on your energy systems and prepare an equipment list. Then use consumption information to begin the process of SEU identification. To accomplish this, take the following actions:

• Obtain process flow diagrams – Process flow diagrams are a good place to start because they display the major process equipment in process order and aid identification. Process flow diagrams help an organization understand and organize its operations and energy systems. An Example Process Flow Diagram can be found through the provided link. Note: You might need an enlarged version of the diagram to complete the actions that follow.
• Obtain facility equipment lists – Facility equipment lists may also be needed because they will typically include building systems that are not included in the process flow diagram. Examples of facility systems/equipment include:
  
  • Air conditioners
  • Air handler fans
  • Lighting
  • Water heaters
  • Chillers
  • Cooling tower
  • Computers
  • Office equipment
  • Elevator
  • Compressed air

Example Equipment Lists for a small manufacturer and a commercial building can be found through the provided links. Locate these systems and equipment on the process flow diagram to provide a complete picture of the energy consumers in your organization. Note that it might not be possible to locate every piece of equipment on the diagram but represent at least the major systems in some fashion.

• Show both primary and secondary energy streams on the process flow diagram – It is important to also include secondary forms of energy because the energy systems that supply them can be very energy intensive.

  Gather the data you collected in Step 2.3.1. Obtain name plate data, operating hours, duty factors and load factors for the equipment and processes associated with your uses that you documented on the Energy Use Worksheet. This information is necessary for determining the energy consumption of the different uses and developing an energy balance (see Step 2.5.2). Also gather any submeter or portable equipment measurements you collected and recorded.

• Locate the energy uses you identified in Step 2.2.2 on the process flow diagram and draw a line around the boundary of each – Using the consumption data you collected in Step 2.3.1, add up the average consumption of all the energy consumers within the boundary of the energy use and indicate it on the process flow diagram or in a separate list. Review all the uses you have identified and the associated energy consumption. Ask yourself the following questions:
  
  • Do I have sufficient data for all of the identified uses?
  • Does the list of energy uses and associated consumption distribute the consumption in a reasonable fashion?
  • Does the consumption of one or a few of the energy consumers within an energy use far overshadow others?
  • Are there interactions between energy uses that might require a reevaluation of energy use identification?
  • Does the collection of energy consumers within each use lend itself to data collection and energy performance evaluation?
  • Based on metering availability, would some other organization of energy uses allow for easier or more realistic determination of energy performance?
  • Does the collection of energy consumers within each energy use make sense?

  The above questions will help you evaluate your initial identification of energy uses. You may need to reevaluate and modify your initial designation of energy uses based on the available data and the equipment, system or process interactions. Energy uses should be chosen to account for most of the interactions that will affect their energy performance. Energy uses should also be chosen based on the information available to determine the amount of energy they consume, either through metered data, name plate data, and/or engineering calculations. Consider that the energy uses may range from one piece of equipment to an entire building. If energy consumption is significant, you may want some pieces of equipment to stand alone. Once you are satisfied with the selection, conduct an energy balance to verify the total consumption of all energy uses balances with the total facility consumption (see Step 2.5.2).

• Consider personnel – Finally, consider the personnel whose work activities can or do impact the SEUs or whose job duties significantly affect how energy is procured, used or consumed within the organization. This can be particularly true for personnel responsible for the operation or maintenance of facilities, equipment, systems or processes identified as SEUs. As the energy management system is implemented, such personnel may need additional training or specific qualifications to ensure that operational controls are followed and energy performance objectives are achieved. Example Personnel Associated with Significant Energy Uses can be found through the provided link.

2.5.2 Develop an energy balance

An energy balance is one reliable approach for providing reasonable assurance that you have accounted for all energy use in your organization. Link the total energy provided to your organization to specific equipment and systems (see Step 2.2.2). The amount of energy consumed by the equipment and systems must closely match the total energy consumed by your organization. Obtaining a match (usually +/- about 5%) provides an indication that equipment and system consumption estimates are accurate. A methodology for conducting an energy balance is available here.

The energy consumption of specific equipment and systems can be determined through metered data, but a calculation using information from other sources, such as name plate data or portable meters (see Step 2.3.1) can provide a good approximation. Over time, the energy consumption can be refined by using meters or by becoming more familiar with the operation of the energy systems.

The DOE Energy Footprint tool develops an energy balance for commercial buildings or industrial facilities. It assists the user to balance the amount of energy calculated from the aggregate of major equipment, systems and processes relative to the total energy of all energy sources.

An Example Energy Balance performed by the Energy Footprint tool for a small food processing manufacturer is available. The balance was determined using the Example Process Flow Diagram and Example Industrial Plant Equipment List presented in Step 2.5.1. A bar chart developed for the calculated energy consumption clearly shows the largest consumers.

2.5.3 Determine and apply criteria for significance

Recall that per the definition of significant energy uses, substantial energy consumption and/or considerable opportunity for improvement are the factors used in determining your organization’s significant energy uses. Most organizations will determine SEUs based on the largest energy consuming systems and equipment identified in the energy balance. But, SEUs also may be determined based on considerable potential for energy performance improvement. This can be a good option if your organization has been engaged in energy management activities for many years. Your organization may have either limited or no viable opportunities for additional improvements to your largest energy consuming systems, so you can focus on smaller systems that have greater opportunity.

Beyond substantial energy consumption and/or considerable potential for improvements, your organization can further refine your criteria for SEUs by taking into account other relevant factors such as carbon footprint, health and safety concerns, or energy costs. If appropriate, the energy team can determine other possible relevant criteria, such as:

• Legal and other requirements – An organization’s commitment to GHG reduction could make a low carbon energy source a priority.
• Business plans – Cost reduction may be the most important factor during an economic downturn and the most expensive energy source could become a priority; or the energy system with largest potential for cost savings could be a priority.
• Expense or process criticality – Any modifications to some operations may be too expensive and beyond your organization’s ability to consider. Alternatively, some processes may have to operate continuously for years at a time and cannot be shut down to allow for modifications.

Although secondary factors may be considered in determining the SEUs, the primary criteria for significance are substantial energy consumption and/or considerable potential for energy performance improvement in your organization. In Step 2.5.2, the energy balance was presented as a method of reasonable assurance that you have accounted for all the energy consumed in your organization. Once a balance is achieved, one of the most common methods for determining SEUs is ordering the uses by consumption. You then establish a certain threshold of energy consumption or a certain percentage of total consumption as the selection criterion for significance (see Step 2.4.1). The top energy consumers are then evaluated for improvement opportunities.

In industry and many businesses, the 80/20 rule typically applies (see Step 2.4.1); i.e. 80% of the energy consumption will be accounted for by 20% of the equipment or processes. Typically only a few energy systems consume the majority of energy in a facility. Focus on these and apply the criteria set for determining SEUs. Energy management is a continual improvement process and over time additional energy systems can be identified as significant.

For newly implemented energy management systems, it is important to start simple. Many organizations just starting energy management want to bring all of their major systems under control. Seriously consider determining only a limited number of SEUs since these energy uses require the most resources. ISO 50001 requires that you address competency of personnel whose work is related to SEUs (see Step 3.4), operational control (see Step 3.5), procurement (see Step 3.7) and monitoring and measurement (see Step 4.1) for all the SEUs you identify. You also take SEUs into account when establishing objectives and targets (see Step 2.9). These requirements can quickly consume available resources.

A list of the SEUs and the method used to determine them is an important energy management planning document. You will need to record the evaluation and selection criterion and the process used to determine significance. The methodology may change over time and changes to the method must also be recorded. A worksheet is available to help document the criteria and method used to determine significant energy uses.

Making SEU Connections – Record the significant energy uses, the areas or operations with which they are associated, along with the affected personnel (by position title) by completing Columns 1, 2 and 5 on the Significant Energy Use Control Chart. This simple spreadsheet tool can serve as the list of current significant energy uses and a place to document other information that will be needed to ensure significant energy uses are properly managed. An Example Significant Energy Use Control Chart is also provided. The other information about SEUs (i.e. Columns 4, 6, 7 and 8 in the SEU Control Chart) will be generated in Step 3.5.2 , Step 4.1.4 and Step 4.1.10.

2.5.4 Identify relevant variables affecting SEUs

Factors that can affect SEUs are called relevant variables. Production is generally one of the key variables impacting energy consumption of SEUs. As production changes, consumption will generally change proportionately. However, consumption and significant energy uses can be influenced by other production related factors or factors other than production. In commercial organizations, occupancy or weather may be key variables affecting consumption. Examine the correlation of SEUs with other relevant variables to understand their impact on energy performance. Relevant variables that may be important and their possible impacts on energy consumption include:

• Weather – Temperature changes can affect heating and drying processes requiring more energy as temperatures drop and less energy as they rise. Heating for personnel comfort will also be impacted by the weather. Other weather characteristics (e.g. humidity, wind, rain, etc.) may also affect energy consumption.
• Operating schedule (e.g. hours, days, weeks, holidays) – A longer schedule will require more energy.
• Occupancy – An increase in the number of individuals in a building can require more energy for air conditioning in the building’s cooling season due to increased cooling load. Similarly, increased occupancy could require more energy for heating during cold weather due to an increase in the number of individuals entering and leaving the building.
• Product mix – Each different product produced by the organization will consume a different amount of energy. Consequently, the mix of the products produced will affect energy consumption.
• Input variations, e.g. materials or moisture levels – Variations in material characteristics or moisture levels could affect energy required for forming, cutting, drying, evaporation, product temperature, etc.
• Output variations, e.g. model or number of units – Changes in the number of models produced or in the number of units produced will affect consumption.
• Season of the year – Products or services that have seasonal demand will influence production and affect consumption.
• Production line(s) and/or SEUs in operation – The number or the size of the production lines or SEUs that are in operation will affect consumption.

Production is typically an important variable in determining energy consumption in industrial facilities and occupancy is typically important in commercial buildings. But consider there may be more than one variable that impacts consumption. Factoring in other relevant variables may help you more clearly define the correlation between energy consumption and productive output. Understanding the relationship between relevant variables and energy consumption is important in your understanding of how energy can be controlled and energy performance maximized.

Verify the impact on SEUs of specific variables by collecting relevant energy data and comparing it to appropriate variable data to determine the relationship, if any, of the change in energy consumption coinciding with the change in the variable. One way to define the relationship is to graph the energy data over a defined time period and compare it to a graph of the variable data, e.g. average daily temperature, over the same period and determine if there are coincidental variations. Consistent variations between the two could indicate a valid relevant variable. Anomalies between the two may indicate other relevant variables are also a factor in energy consumption of the SEU. Statistical techniques or more sophisticated engineering calculations may be required for analysis of multiple variables.

2.5.5 Determine current energy performance and implement monitoring

Once the SEUs are identified, collect appropriate energy data to determine their performance. A best practice is to include their energy performance data and information within the energy tracking system (see Step 2.4.1). This brings all of the organization’s energy data into one central location. Normal analysis and tracking of energy data will then include updating energy performance on the SEUs.

An energy performance indicator (EnPI) (see Step 2.7) can be developed to define the energy performance for a SEU. There are generally accepted EnPIs for many common energy systems that are often identified as SEUs. Similar EnPIs can be developed for facilities, equipment, processes, personnel or other systems. Track the EnPIs to reveal trends that allow comparison of the performance of SEUs over time. Benchmarking, which is the practice of comparing an SEU to the best in class or theoretically optimal performance of similar uses, may be used when available (see Step 2.4.1).

An example of EnPI tracking for steel melt furnace energy performance is included. The example presents furnace performance expressed as kWh/ton for two shifts over a three week period. The example illustrates how EnPIs can be used to track SEU performance over time and how operating personnel can impact the energy performance of the significant energy use.

Energy performance of a SEU also can be determined and monitored by operational or maintenance parameters (see Step 4.1.4). For example:

Energy performance of an air conditioning system can be determined by monitoring the air temperature and flow from the registers. A temperature increase indicates an energy performance decrease which could be due to several factors including elevated outside air temperature, dirty coils, refrigerant leak, etc. A decreased air flow could signal a clogged air filter, dirty coils, dirty fan blades, etc.

SEUs are among the “key characteristics” of energy performance that are regularly monitored, measured and analyzed (see Step 4.1). Your organization determines the method for determining energy performance and identifies the monitoring and measurement necessary for data collection. Data analysis is a continuous process. Continue to monitor the SEUs and collect, analyze and track data to identify opportunities for energy performance improvement.

2.5.6 Calculate future energy use and consumption

Because SEUs typically account for a major portion of an organization’s energy consumption, projection of their future energy consumption is an important part of energy planning. Projections allow for an organization to look at the factors that could affect consumption and make important decisions about production, energy projects, technology implementation, sources, availability, etc. To assist with projecting energy consumption of significant uses, a SEU Future Energy Estimate Worksheet is available. Complete one estimate for each SEU. You can estimate potential changes in SEU consumption based on the effects of various factors.

To help identify the factors important to your organization, you may want to consider:

• Occupancy
• Production
• Capital investment
• Replacement energy sources
• Completed energy projects
• New technologies
• Process changes
• Materials changes
• Product criteria
• Weather
• Operational criteria
• Changes to the economy
• Business or industry sector change

Develop a future energy consumption estimate for SEUs to provide an early warning about anticipated changes occurring in your organization and use it as a reference to evaluate results.

2.5.7 Plan for updating the significant energy uses

Establish a plan for the energy team to review and update the SEUs and the evaluation and selection methodology on a regular basis. Changes in the list or the evaluation and selection process may be necessary because:

• Improvement projects have reduced consumption of an SEU below the selection threshold
• Resources are not adequate to address the number of SEUs selected
• Additional resources are available to address more SEUs
• Business changes have affected SEU focus/selection
• New processes have altered energy consumption patterns

The energy team should regularly review the SEUs and the evaluation and selection methodology with management input. The team can then make changes as necessary to ensure continual energy performance improvement within your organization’s available resources.

The following resources provide assistance with identifying and working with significant energy uses.

• Example Process Flow Diagram
• Example Industrial Plant Equipment List
• Example Commercial Building Equipment List
• Energy Use Worksheet
• Example Personnel Associated with Significant Energy Uses
• Energy Balance Methodology
• Example Energy Balance
• Plant Energy Profiler
• Worksheet for Documenting SEU Criteria and Method
• Significant Energy Uses Control Chart (Step 2.5.3)
• Example Significant Energy Uses Control Chart
• Example Energy Performance Indicators (EnPIs) for Common Energy Systems
• Example EnPI Tracking
• SEU Future Energy Estimate Worksheet

Single license electronic copies of the ISO 50001 standard can be purchased from GTESS.

Site licenses (for posting on internal networks) can be purchased from ANSI.

The following resources provide information needed to understand EnMS documentation and decide what documents and records are needed for your EnMS.

• Understanding EnMS Documentation
• EnMS Documentation Guidance Table
• Energy Manual Guidelines