ASHRAE Energy Audit Levels 1, 2, and 3
A commercial building energy analysis can generally be classified into the
following three levels of effort:
Preliminary Energy-Use Analysis (PEA)
The PEA precedes an audit of the building. During the PEA the analyst
analyzes the historic utility use, peak demand, and cost; develops the Energy
Cost Index (ECI) of the building (expressed in dollars per floor area per year);
and develops the Energy Utilization Index (EUI) of the building (expressed in
kBtu/ft2 [MJ/m2] per year).
Level 1—Walk-Through Survey
First, the building’s energy cost and efficiency are assessed by analyzing
energy bills, compiled in the PEA, and conducting a brief on-site survey of the
building. A Level 1 energy survey will identify low-cost/no-cost measures for improving energy efficiency and provide a listing of potential capital improvements
that merit further consideration. Because calculations at this level are
minimal, savings and costs are approximate.
Level 2—Energy Survey Analysis
A Level 2 audit involves a more detailed building survey, including energy
consumption and peak demand analysis. A breakdown of energy end uses
within the building is developed.
Level 3—Detailed Analysis of Capital Intensive Modifications
The third level of engineering analysis focuses on potential capital-intensive
projects identified during a Level 2 analysis. It requires more detailed field data
gathering as well as more rigorous engineering and economic analyses, often
including modeling (simulation) of the annual energy performance of the building
and vendor pricing.
In addition, there is a Preliminary Energy-Use Analysis (PEA), which is a
prerequisite for any audit, and there are targeted audits, which do not have a
strictly defined level of effort but may be useful or necessary for some situations.