Energy Audit Overview |



All energy management programs must begin with some sort of energy audit. If it’s not measured, there’s no way to know if any change has been made; without some sort of audit or plan, there’s no way to know what should be measured. The primary purpose of the initial energy audit is identification. Subsequent audits can be used to dig into the details in order to estimate the savings potential and measure results.

Successful energy management is not a one-time activity. It requires continuous work, enforcement, evaluation and adjustment. If it’s not working, find out why. Make corrections or do something else.

Types of Audits

The Walk-Through – Level 1

The most common audit is the ‘Walk-Through’ (Walk-Thru). A walk-thru energy audit may be performed by a sales person attempting to make a case for their product, a utility representative, university students, retired engineers, in-house personnel such as members of an energy committee, hired consultants or any combination of these. The walk-thru may be for the entire facility lasting several hours or days, or be focused on one specific process or machine. Generally what defines a walk-thru from a detailed analysis is that no/minimal instruments are used/measurements taken and all data is gathered at one time. The primary purpose of the walk-thru is to identify energy using equipment and prioritize equipment and processes that may have a savings potential.

Detailed Audit – Level 2

The Detailed energy audit typically starts with a walk-thru that identified potential savings that required a detailed audit to confirm. A detailed audit typically focuses on certain areas or processes of the facility in extensive detail. Measurements are taken and data gathered over an extended period of time. The data is evaluated and calculations made to determine cost and savings potential of making changes. Detailed audits can take several days to several months to complete.

Comprehensive Audit – Investment Grade Audit – Level 3

The Level 3 Audit is required when the project may be very complicated and/or expensive. This audit may take several days to gather data and several weeks or months to evaluate the results and come to recommendations. The results will also likely include engineering design with enough detail that it can be used to obtain cost bids to complete the project.


Industrial Assessment Centers

Several colleges and universities across the US work in conjunction with the Department of Energy (DOE) to offer Industrial Energy Assessments. These audits are completed by students and are free to the recipient. There are currently 26 Industrial Assessment Centers located at colleges and universities across the US.

For more information see


Plant Wide Energy Assessments

The DOE also offers co-funding for detailed assessments that cost up to $100,000. These assessments are completed by a team of consultants and facility personnel who have applied to the DOE for audit funding.

For more information see



Shared Savings Programs

Although not as popular as they were 10 years ago, many ‘shared savings’ programs are still available. Many vendors will offer to perform an energy audit and complete Measures for no up front costs to the recipient. The recipient is under contract to pay the vendor either a percentage or a flat monthly fee based on the energy savings as reflected in the utility bill.

These programs are great for facilities that have a lot of energy savings potential but no capital to take on the Measures themselves. They are very popular at schools and government facilities. However, there are also many potential problems if savings result to be lower than one or both of the parties expected. The reasons for the weak results (who’s to blame) and how to pay for the Measures can get real ugly. The details are in the Contracts. KNOW what is being agreed to, BEFORE entering into any such program that “…looks too good to be true….”


General Audit Process

The general steps involved in an energy audit is outlined below. How much time these steps will take and the amount of detail to be gathered, is highly dependent on the size of the facility, the complexity of the processes it contains, the skill of the auditor(s), the desired results, and how much information is already known at the start of the audit.

  1. Assemble the Team that will be responsible for the Energy Audit Project.
  2. Pre-Audit Data. Gather as much pre-audit data as possible, including:
      1. 12 – 24 months of utility bills (actual units of usage, not just dollar costs)
      2. Previous audit results
      3. Equipment Inventories from maintenance records, leases, tax records, etc.
      4. Production Records – units of product made during a given time
      5. Data gathering forms – create or obtain forms that can make data gathering easier
  3. Plan the walk-thru Audit Time. If an outside consultant is being used, it is best to have the audit during a time of normal production/ normal activities. This helps the consultant see first-hand how things are done and should provide details that would not be included in simply talking about the process. On the other hand, if using in-house people who are very familiar with the process, doing the walk-thru during a time of non-production may provide an opportunity to get closer to machinery and talk to operators who may be too busy to talk during production time.
  4. Gather Data on ALL major energy using equipment. If it has a power line and/or gas connection, write-down:
      1. The name of the equipment (actual name, number and ‘common name’ used in the facility)
      2. What process(es) it is used in
      3. BTU Input Rating (gas); watts or Horse Power Rating (electric); for fans CFM Rating
      4. Typical operating schedule (hours per day, days per week)
      5. Estimated Load Factor;;is the equipment always on or cycled when in use; see Load Factors
      6. If also including water/sewer data, GPM Water Usage that is dumped to drain
      7. Steam and/or hot water usage that is lost to the product (NOT BTUs but live steam/water that does NOT return to the boiler)
      8. Take a digital photo of the equipmentNOTE: For small pieces of equipment, such as hand tools and fractional horsepower machinery, it is probably not necessary to gather data. Consider the size of the facility and the quantity of the equipment when deciding what to gather information on.
  5. Compile Data. Most auditors still use pen and paper. Others may use a PDA or Tablet PC to input data directly into a spreadsheet. Using whatever system was established in Step 2 above, compile all data into a common format that can be used to compare equipment. Spreadsheets that can sort data are the most helpful; for large facilities, databases are better, but more difficult for the average user to program.
  6. Estimate Energy Usage of each major piece of equipment. See Energy Calculations
  7. Determine the Largest Energy Users by ranking and sorting the results of Step 6 above
  8. Compile a list of Practices and Measures by prioritizing the largest energy users and what practical steps can be taken to reduce energy usage. This can be the most difficult step, because it requires an awareness and knowledge of what can be done and what’s practical to be done according to costs and impact on production. There is always a better ‘mouse trap’; the primary issue is (and where we separate the experts from the ‘want-ta-bees’) is what makes sense.
  9. Start the Analysis by focusing on the major energy users and which Measures appear to have the most potential. Select perhaps the top 6 to do a detailed analysis on. Gather some details from sources such as manufacturer’s reps, web sites, others who may have taken the same Measure, etc. Obtain cost and savings estimates, and actual results from Case Studies, where available. Take measurements on the equipment/process over a period of time in order to confirm energy usage estimates.
  10. Prioritize Recommendations based on the results of Step 9 above
  11. Create an Action Plan that details what steps will be taken to reduce energy usage/costs. Get the appropriate approvals, budget, permits and whatever else may be required to implement the Plan.
  12. Work the Plan and Check for Results. Successful energy management is not a one-time activity. It requires continuous work, enforcement, evaluation and adjustment. If it’s not working, find out why. Make corrections or do something else.




Source: Text Bob Fegan 1/2009


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