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Journey to Sustainability

Energy Auditing Basics

Energy Audit

Energy Auditing Basics


Energy audits can mean different things to different individuals. The scope of an energy audit, the complexity of calculations, and the level of economic evaluation are all issues that may be handled differently by each individual auditor and should be defined prior to beginning any audit activities. This chapter will review the various approaches to energy auditing and outline a standard approach to organizing and conducting an energy audit.

An energy audit can be simply defined as a process of determining the types and costs of energy use in the building, evaluating where a building or plant uses energy, and identifying opportunities to reduce consumption

There is a direct relationship to the cost of the audit, how much data will be collected and analyzed, and the number of conservation opportunities identified. Thus, a first distinction is made between cost of the audit which determines the type of audit to be performed. The second distinction is made between the type of facility. For example, a building audit may emphasize the building envelope, lighting, heating, and ventilation requirements. On the other hand, an audit of an industrial plant emphasizes the process requirements.


Before starting the energy audit, it is helpful to have some idea of the scope of the project and level of effort necessary to meet expectations. There are four basic types or levels of energy audit, any of which may meet your requirements.

The basic audit levels, in order of increasing complexity are:

Type 0-The Benchmarking Audit

This audit includes performing a detailed preliminary analysis of energy use and costs, and determining benchmark indices like Btu per square foot per year and dollars of energy cost per square foot per year, based on utility bills. Very cost effective for multiple facilities. The EPA/ DOE EnergyStar Portfolio Manager is one of the best and easiest tools to use and it is free.

Type I-The Walk-through Audit

The walk-through audit, as its name implies, is a tour of the facility to visually inspect each of the energy using systems. It will typically include an evaluation of energy consumption data to analyze energy use quantities and patterns as well as provide comparisons to industry averages or benchmarks for similar facilities. It is the least costly audit but can yield a preliminary estimate of savings potential and provide a list of low-cost savings opportunities through improvements in operational and maintenance practices. The level one audit is also an opportunity to collect information for a more detailed audit later on if the preliminary savings potential appears to warrant an expanded scope of auditing activity.

Type II-Standard Audit

The standard audit goes on to quantify energy uses and losses through a more detailed review and analysis of equipment, systems, and operational characteristics. This analysis may also include some on-site measurement and testing to quantify energy use and efficiency of various systems. Standard energy engineering calculations are used to analyze efficiencies and calculate energy and costs savings based on improvements and changes to each system. The standard audit will also include an economic analysis of recommended conservation measures.

Type III-Computer Simulation

The level three audit will include more detail of energy use by function and a more comprehensive evaluation of energy use patterns. This is accomplished through use of computer simulation software. The auditor will develop a computer simulation of building systems that will account for weather and other variables and predict year-round energy use. The auditor’s goal is to build a base for comparison that is consistent with the actual energy consumption of the facility. After this baseline is built, the auditor will then make changes to improve efficiency of various systems and measure the effects compared to the baseline. This method also accounts for interactions between systems to help prevent overestimation of savings. Because of the time involved in collecting detailed equipment in- formation, operational data, and setting up an accurate computer model, this is the most expensive level of energy audit but may be warranted if the facility or systems are more complex in nature.


(Ref. Procedures for Commercial Buildings Energy Audits, 2005 ASIIRAE)

ASHRAE has formalized a set of energy audit definitions that are widely used by energy auditors. The source of the following definitions is the 2005 ASHRAE Handbook of HVAC Systems.

Preliminary Energy Use Analysis. This involves analysis of historic utility use and cost and development of the energy utilization index (EUI) of the building. Compare the building’s EUI to similar buildings to determine if further engineering study and analysis are likely to produce significant energy savings.”

We have also identified this as a Benchmark Audit.

Level 1: Walk-Through Analysis. This assesses a building’s current energy cost and efficiency by analyzing energy bills and briefly surveying the building. The auditor should be accompanied by the building operator. Level 1 analysis identifies low-cost/no-cost measures and capital improvements that merit further consideration, along with an initial estimate of costs and savings. The level of detail depends on the experience of the auditor and the client’s specifications. The Level I audit is most applicable when there is some doubt about the energy savings potential of a building, or when an owner wishes to establish which buildings in a portfolio have the greatest potential savings. The results can be used to develop a priority list for a Level II or III audit.”

  • Also known as the “one-day” or “walk-through” audit, this approach involves a cursory analysis of energy bills and a brief survey of the building to produce a rough estimate of how efficiently energy is used in the building
  • This level of effort will detect at least some of the “low-hanging fruit” and may suggest other options worthy of more study, but should never be viewed as comprehensive.
  • Although this option is easiest, it also produces the crudest results, so don’t be tempted into thinking you’re done once you do this much you’ve really only gotten started.

Level II: Energy Survey and Analysis. This includes a more detailed building survey and energy analysis, including a breakdown of energy use in the building, a savings and cost analysis of all practical measures that meet the owner’s constraints, and a discussion of any effect on operation and maintenance procedures. It also lists potential capital-intensive improvements that require more thorough data collection and analysis, along with an initial judgment of potential costs and savings. This level of analysis is adequate for most buildings.”

  • By investing more effort in the building survey and energy analysis, and by adding some system performance testing, this method provides a breakdown of how energy is used in the building as well as a broader range of savings options, including simple capital investments.
  • It accounts for the “people factor” and its effect on uncertainty of savings, and also explores maintenance procedures and assesses any impacts savings measures may have on them.
  • Many facilities will find this level of analysis to be sufficient.

Level III: Detailed Analysis of Capital-Intensive Modifications. This focuses on potential capital-intensive projects identified during Level II and involves more detailed field data gathering and engineering analysis. It provides detailed project cost and savings information with a level of confidence high enough for major capital investment decisions.

The levels of energy audits do not have sharp boundaries. They are general categories for identifying the type of information that can be expected and an indication of the level of confidence in the results. In a complete energy management program, Level II audits should be per formed on all facilities.

A thorough systems approach produces the best results. This approach has been described as starting at the end rather than at the beginning. For example, consider a factory with steam boilers in constant operation. An expedient (and often cost-effective) approach is to measure the combustion efficiency of each boiler and to improve boiler efficiency. Beginning, at the end requires finding all or most of the end uses of steam in the plant, which could reveal considerable waste by venting to the atmosphere, defective steam traps, uninsulated lines, and lines through unused heat exchangers. Eliminating end-use waste can produce greater savings than improving boiler efficiency.

A detailed process for conducting audits is outlined in ASHRAE (2004)

  • Even more detailed data are gathered from field equipment. Extensive test measurements are taken which may include spot measurements and short-term energy monitoring. Possible risks are assessed, and intensive engineering and economic analysis produces reliable estimates of project energy and financial performance with the high confidence needed for major capital projects.
  • Although not defined by ASHRAE as an Investment Grade Audit, it is often called this by many energy auditors.
  • This analysis digs into the details of any large capital projects you may be considering as a result of previous, simpler audits. AEE, as well as many others, requires computer simulation to be part of an investment grade audit.
  • These audit approaches tend to overlap in practice. All three assess the potential energy savings and initial cost of various energy savings strategies, so in that sense all are similar. The differences are in your confidence that you’ve truly found all your savings opportunities, the accuracy of the expected savings and initial cost, and how much information you have about the difficulty of the project implementation and the likely persistence of the savings over time. The devil is definitely in the details.
  • All level II and level III audits involve collecting general building data (location, size, usage type, energy sources), historical energy use data, and energy systems data (type of equipment in the envelope, lighting, HVAC, service water, etc.) to get a description of the facility. The more detailed the available data are, the more complete this description can be. For example, submetering within a building makes it easy to call out specific end uses or facility areas, and having daily or even hourly consumption data allows you to call out time patterns normally buried within the monthly billing cycle.
  • All these data then feed an energy use analysis that lays out how much energy is consumed for each major end use in the building, such as space heating, space cooling, lighting, air distribution, etc. This defines a baseline scenario for future years, is no energy projects are undertaken. A similar analysis can be done with respect to peak energy demand
  • If you’re serious about saving as much energy cost as possible with the quickest payback time and least hassle, take the time to plan your energy projects right. Perform a good energy audit, and assess its results carefully based on the needs of your facility, whether based on annual savings, initial cost, payback time, synergistic comfort benefits to occupants, or recurring maintenance hassle. The rewards are well worth the work.


In most facilities, companies, and other corporate settings, upgrades to a facility’s energy infrastructure must compete for capital funding with non-energy-related investments. Both energy and non-energy investments are commonly rated on a standard set of financial criteria that generally stress the expected return on investment (ROI) and often the life cycle costs. The projected operating savings from the implementation of energy projects must be developed such that they provide a high level of confidence. In fact, investors often demand guaranteed savings. The investment-grade audit expands on the detailed audit Levels II and III above, and relies on complete engineering studies in order to detail technical and economic issues necessary to justify the investment related to the transformations. In most cases, detailed hour-by-hour computer simulation modeling will be required. The formal AEE description of the investment grade energy audit is:

Investment Grade Audit

  • This audit includes weighing financial risk into the economic calculations of a type II or III energy audit.
  • It will often include computer simulation and enhanced financial analysis tools such as life cycle costing. Additional requirements may be specified by individual clients.
  • This audit can be utilized to obtain funding for the projects identified.

The Association of Energy Engineers has developed three certification programs for professionals practicing energy auditing: The Certified Energy Auditor (CEA) Program, The Master’s Level CEA Certification Program, and the Certified Energy Manager (CEM) Program.



The Mark of an Energy Professional In 2006, the Certified Energy Auditor (CEA) and Certified Energy Auditor in Training (CEAIT) certifications were developed and added to the impressive portfolio of certifications offered by the Association of Energy Engineers. Rising energy costs and inefficiency in plants and buildings is continually driving the need for trained and experienced energy auditors. The CEA certification is one that identifies professionals as having the required knowledge and experience needed to succeed in the growing field of energy auditing.

  • To raise the professional standards of those engaged in energy auditing.
  • To improve the practice of energy auditors by encouraging energy auditing in a continuing education program of professional development.
  • To identify persons with acceptable knowledge of the principles and practices of energy auditing through completing an examination and fulfilling prescribed standards of performance and conduct.
  • To award special recognition to those energy auditing professionals who have demonstrated a high level of competence and ethical fitness in energy auditing.

The Certified Energy Manager (CEM) Program for Professional Certification



When you’ve earned the right to put the initials “CEM” behind your name, you’ve distinguished yourself among energy management professionals. Simply put, the designation CEM, which stands for Certified Energy Manager, recognizes individuals who have demonstrated high levels of experience, competence, proficiency, and ethical fitness in the energy management profession. By attaining the status of CEM, you will be joining an elite group of 6,000 professionals serving industry, business and government throughout the U.S. and in 22 countries abroad. These high-achieving individuals comprise a “Who’s Who” in the energy management field.

The Master’s Level Certified Energy Auditor (CEAM) Program

New for 2012 and developed with grant funding from the US Department of Energy, the Master’s Level Certified Energy Auditor (MCEA) certification is designed to reach beyond the typical equipment replacements and develop a plan which considers additional areas of energy such as indoor air quality, code compliance, operation and maintenance, risk mitigation, commissioning, and investment grade details.

  • To raise the professional standards of those engaged in energy auditing.
  • To improve the practice of energy auditors by encouraging energy auditing in a continuing education program of professional development.
  • To identify persons with acceptable knowledge of the principles and practices of energy auditing through completing an examination and fulfilling prescribed standards of performance and conduct.
  • To award special recognition to those energy auditing professionals who have demonstrated a high level of competence and ethical fitness in energy auditing.
The Mark of An Energy Professional

Since its inception in 1981, the Certified Energy Manager (CEM®) credential has become widely accepted and used as a measure of professional accomplishment within the energy management field. It has gained industry-wide use as the standard for qualifying energy professionals both in the United States and abroad. It is recognized by the U.S. Department of Energy, the Office of Federal Energy Management Programs (FEMP), and the U.S. Agency for International Development, as well as by numerous state energy offices, major utilities, corporations and energy service compony.


The first step in any energy audit should be to collect energy bills and perform a benchmark audit. Once you have established the level of actual audit to be performed, you can begin collecting information on the structural and mechanical components that affect building energy use, and about the operational characteristics of the facility. Much of this information can and should be collected prior to the actual site-visit. A thorough evaluation of energy use and systems before going on-site will help identify areas of savings potential and help make best use of your on-site time.

An organized approach to auditing will help you collect useful information and reduce the amount of time spent evaluating your facility. By splitting the audit process into three distinct components, pre-site work, the site visit, and post-site work, it becomes easier to allocate your time for each step and leads to a more comprehensive and useful audit report. The following sections describe the tasks associated with each step of the audit process.


Pre-site work is important in getting to know basic aspects of the building. This preparation will help ensure the most effective use of your on-site time and minimize disruptions to building personnel.

A thorough pre-site review will also reduce the time required to complete the on-site portion of the audit. The pre-site review of building systems and operation should generate a list of specific questions and issues to be discussed during the actual visit to the facility.

Pre-site Tasks

1) Collect and review one to two years of utility energy data. Tabulate and graph the data. Check for seasonal patterns, unusual spikes, and accuracy of the billings. Graphing consumption and cost data makes it easier to understand how each building uses energy. By determining seasonal and base loads, then apportioning energy use among specific building systems such as heating, cooling, lighting and hot water, it becomes easier to identify areas with the greatest


savings potential. It’s also important to include electric demand kilowatts and demand charges in your evaluation. (See Energy Accounting section for additional information on utility bill analysis.) Pie charts of energy use and cost by fuel type can offer compelling documentation of overall energy uses and expenses.

2) Obtain mechanical, architectural, and electrical drawings and specifications for the original building as well as for any additions or remodeling work that may have been done. Try the local building department or original architect if the owner doesn’t have them. If any energy audits or studies have been done in the past, obtain a copy and review them.

3) Draw a simple floor plan of the building on 8-1/2 x 11 or 11 x 17 inch paper. Make several copies to use for taking notes during the actual site visit. Use separate copies for noting information on locations of HVAC equipment and controls, heating zones, light levels and other energy related systems.

4) Calculate the gross square footage of conditioned space using outside building dimensions multiplied by the number of stories. Substantial areas that are not conditioned and occupied can be subtracted from the gross square footage.

5) Use audit data forms to collect, organize and document all pertinent building and equipment data. Audit workbooks containing checklists, equipment schedules, and other forms are available from a variety of sources including US Department of Energy, Energy- Star, ASHRAE, and your State Energy Office. You may also find it useful to develop your own forms to meet your specific needs. To save time, fill out as much of the form as possible using the building plans and specifications before starting on-site work.

6) Develop a building profile narrative that includes age, occupancy, description, and existing conditions of architectural, mechanical, and electrical systems. Note the major energy consuming equipment or systems.

7) Calculate the energy use index (EUI) in Btu/sq ft/year and compare it with EUls of similar building types using the chart in the energy accounting section. The EUI is calculated by converting annual consumption of all fuels to Btus then dividing by the gross square footage of the building. It can be a good indicator of the relative potential for energy savings. A comparatively low EUI indicates less potential for large energy savings.

A great, free resource is available from EnergyStar. The Portfolio Manager is an easy-to-use, free benchmarking program available from This process is called a benchmark audit.

While completing your pre-site review, note areas of particular interest and write down any questions you may have in advance. Typical questions may concern lighting type and controls, HVAC zone controls or morning warm-up operation. Other questions may be on maintenance practices for pieces of equipment you’ve identified which typically require regular servicing.

If you are auditing a building other than one you operate, obtain the data discussed above and confirm your preliminary observations with the building manager or operator by phone prior to your visit. Ask them if they are interested in particular conservation projects or planning changes to the building or its systems. Try to schedule the audit at a time when the systems you want to check are in operation and arrange to have the building operator accompany you during the site visit.

Develop a list of potential energy conservation measures (ECMS) and operation and maintenance (O&M) procedures as you conduct this preliminary research. Your state energy office or local utility companies should be able to provide you with more information on conservation technologies and O&M recommendations. If you do some homework first, you will be better able to discuss energy saving measures with the building manager.

Develop a Site Sketch

Prepare a site sketch of the building or complex which shows the following information:

  • Relative location and outline of the building(s).
  • Name and building number of each building. (Assign building numbers if none exist.)
  • Year of construction of each building and additions.
  • Square footage of each building and additions.
  • Location, fuel type and I.D. numbers of utility meters.
  • Areas served by each utility meter.
  • Location of heating and cooling plants and equipment.
  • North orientation arrow.
The Site Visit

With pre-site work completed, you should have a basic under- standing of the building and its systems. The site visit will be spent inspecting actual systems and answering specific questions from your pre-site review.

Plan to spend at least a full day on-site for each building. The amount of time required will vary depending on the completeness of the pre-site information collected, the complexity of the building and systems, and the need for testing of equipment. Small buildings may take less time. Larger buildings can take two days or more.

Here are some steps to help you conduct an effective audit:

Have all necessary tools available on site. Try to anticipate basic hand tools and test equipment you will need to perform a thorough inspection. Some basic audit tools you’ll want to bring along include:




-Tape Measure

-Pocket Thermometer

-Light Meter

-Pocket Knife



-Mini Data Loggers

A more detailed description of specialized audit instrumentation is included in Chapter 4.

  • Prior to touring the facility, sit down with the building manager to review energy consumption profiles and discuss aspects of the facility you aren’t able to see such as occupancy schedules, operation and maintenance practices, and future plans that may have an impact on energy consumption.
  • Confirm the floor plan on your drawing to the actual building and note major changes. Use copies of the floor plan to note equip ment locations such as boilers, chillers, DHW heaters, kitchen appliances, exhaust fans, etc., as well as lighting types, levels, and switching, photo locations, room temperatures, general conditions and other observations.
  • Fill out the audit data sheets. Use them to organize your site visit and as a reminder to collect information missing from pre-site documents.
  • Look at the systems relating to the ECMs and O&Ms on your preliminary list. Review the application of your recommendations and note any problems that may affect implementation. Add additional measures to your list as you tour the facility.
  • Take pictures as you walk through the building. Include me- chanical equipment, lighting, interior workspaces, common areas and halls, and the exterior including the roof. They are useful in documenting existing conditions, discussing problems and issues with colleagues, as well as serving as a reminder of what you inspected. Building managers will find them useful for explaining conservation measures to administrators and building occupants.

    Take basic measurements of light levels, temperature, relative hu- midity, and voltages.


    Post-site work is a necessary and important step to ensure the audit will be a useful planning tool. The auditor needs to evaluate the information gathered during the site visit, research possible conserva- tion opportunities, organize the audit into a comprehensive report, and make recommendations on mechanical, structural, operational and maintenance improvements.

    Post-site work includes the following steps:

    Immediately after the audit, review and clarify your notes. Com- plete information you didn’t have time to write down during the audit. Use copies of the floor plan to clean up notes for permanent records.

    Review and revise your proposed ECM and O&M lists. Eliminate those measures lacking potential and document why they were eliminated. Conduct preliminary research on potential conservation measures and note conditions that require further evaluation by an engineer or other specialist.

    Process your photos and paste or import pictures on 8-1/2 x 11 inch pages. Number the photographs and note on a floor plan the location where each photo was taken. Identify and add notes under the pictures as needed.

    Organize all charts, graphs, building descriptions, audit data sheets, basic measurements, notes and photos into a 3 ring binder.

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