The sequence of events in a Building Energy Audit includes content you review before going out into the field, things to look out for in the field, and activities an auditor conducts back in the office.
Before Going Out into the Field
All levels of energy audits include the Preliminary Energy-Use Analysis that is done before the field visit. In a Preliminary Energy Use Analysis, the auditor uses utility billing data, building documentation, and mechanical/architectural drawings to learn more about the building. The auditor will look for patterns in the data and potential opportunities for energy conservation measures, items that can be further examined in the field.
The Energy Use Intensity (EUI) is a metric used to compare buildings because it looks at energy intensity irrespective of how large or small a building might be. It's calculated by summing the total annual energy use, then dividing this value by the building square footage. A EUI is used to compare buildings because it no longer matters how large or small the building is.
If smart meter data is available for the building, this data can be graphed over different time periods to identify energy load profiles, peak demands, and outliers that need more investigation.
In the Field
When walking through the building, an auditor should document the following building systems (as applicable):
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Building envelope
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Lighting
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Plug Loads
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Heating, Ventilation, and Air Conditioning
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Domestic Hot Water
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Laundry
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Food preparation
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Refrigeration
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Conveying
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Pools/saunas/spas
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Process loads
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Others
Other data to gather in the field includes operating schedules, heating/cooling water temperatures (including domestic hot water, process heating or cooling, supply air, and room), humidity levels, airflow and ventilation rates, and overhead and task lighting levels. These measurements are key operating parameters that can be compared to design levels of building equipment. By comparing the two, auditors are seeing if a building is running as it was originally designed to and if it isn't, these are energy conservation/efficiency measures that are included in the final report.
Back in the Office
Using the information collected during a field visit, an auditor breaks down the annual energy use into its end-use components. This breakdown, along with the preliminary end-use analysis and the data collected in the field, is used to create suggested Energy Conservation Measures (ECMs).
Three types of Energy Conservation Measures:
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Energy Efficiency: replacing old or inefficient equipment with higher efficiency equipment
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Operations & Maintenance: correcting improper equipment operation; verifying standard maintenance, and recommending new or improved operational sequences or schedules
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Load Management: strategies for reducing peak load
An auditor also uses the data collected in the field to list energy conservation and/or efficiency measures for the building. These measures can be modifications to equipment or changes to operations that will save energy. This list is discussed with and prioritized by the building manager based on how likely they are to be implemented. The auditor will then group measures together and analyze the implementation and operational costs as well as the energy savings. In addition to financial and energy calculations, the effect on the Energy Use Intensity (EUI) of the building is also calculated for each measure or group of measures.