Energy Auditing

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Energy Auditing is a tool for identifying Energy Efficiency potential and measures. An energy audit is an important tool or method for finding such potentials for energy efficiency measures and for assessing their financial viability, which can be carried out at different levels. A simple level just includes a brief site inspection as well as assessing the broad energy input and output of a system – this identifies low cost energy saving opportunities. Medium level audits include an in-depth analysis of energy costs, energy usage and system characteristics along with on-site energy demand measurements to identify energy efficiency measures which are more capital intensive and need to be aligned with the financial budget plan of the site. The most sophisticated level, which is referred to as an investment grade audit, includes an additional continuous monitoring of system data and process characteristics.

Energy audits on such comprehensive levels can also form an important basis or first step for introducing and establishing energy management systems (EMS) in enterprises/ other institutions. They enable efficient management of energy demand and consumption in production o processing entities – also in agricultural value chains (International Standard for EMS: ISO 50001).

The Main Goals of Energy Audit

  • Understanding how energy is used within the system or process, and where it is wasted
  • Finding alternative measures to reduce energy losses and improve the overall performance
  • Performing a cost-benefit analysis for highlighting which energy efficiency measures are best to implement

Four differents Phases

1. Review of Energy Use

In this phase of the auditing process the energy use of the system, e.g. a small diary milk factory, is assessed by reviewing the energy bills or the past fuel consumption patterns in the past. Also, a system diagram is sketched showing the energy flows within the system along with a list of used equipment and their energy demand. The more detailed the energy usage data is the better will be the actual analysis. At this point, monthly data is most common; however, daily or even hourly data would be more accurate. With the collected data the auditor is able to calculate the total energy demand for specific scenarios (seasonal variation/ production intensity) and is able to set each system component into comparison. Then, it is possible to determine a “per square meter” energy use or “an energy use per produced product unit”, to benchmark the system against other similar buildings or processes. With these preliminary analyses, experienced auditors can estimate how much potential the system or building bears for efficiency improvements.

2. Site Assessment

During the site assessment, the mentioned system components are examined and their performance data is collected. This step can include, for example, the operation characteristics of a fan used for drying or the lighting used throughout the building. Such a process can vary largely in terms of effort.

3. Data Analysis

The data analysis step is the most complex part of an energy audit and involves technical and cost analysis. Methodologies for analyzing the collected data vary widely and are subject to the system or process to be assessed. The technical analysis can incorporate a simple spreadsheet energy balance where all input and output parameters are determined or can be achieved by designated software packages. The same methods apply for the cost analysis, where current energy costs, costs for implementation of energy efficiency measures as well as potential savings over time are considered. The results of both analyses lead in a further step to a hierarchy of the most promising changes to the system in both financial and technical aspects. Guiding indicators are amongst others the payback period, life cycle costs as well as internal rate of return of the energy efficiency measures. You can find more information about such financial analysis in weeks six and seven of this course. Further aspects to be considered are operation and maintenance of planned implementation, reliability and their ease of installation.

4. Audit Report

The last phase of the auditing process is creating a comprehensive report. Including all recommended energy efficiency measures and how different combinations of lead to cost and energy savings.


  • Energy auditing is the analysis of process or system in regard to their energy usage and energy losses.
  • By reviewing load patterns, executing site visits and measuring process energy demands, suitable energy efficiency measures can be discovered.
  • Energy audit results are useful for economic and environmental betterment of the analyzed processes, thus it is a very important tool in energy sector.

Further Reading