3.1 Energy Audit Methodologies: ASHRAE Level I, II, and III Audit Scopes

The foundation of a successful energy management program begins with the energy audit. An energy audit is a systematic assessment of a facility's energy consumption to identify cost-effective opportunities for improving energy efficiency. The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) has standardized energy audits into three distinct levels of effort, as outlined in their publication 'Procedures for Commercial Building Energy Audits.' For the CEM exam, you must have a solid understanding of the scope, required tasks, and expected deliverables for each of the three ASHRAE audit levels.

Preliminary Energy Use Analysis (PEUA)

Before conducting any level of physical audit, the auditor should perform a Preliminary Energy Use Analysis (PEUA). The PEUA involves analyzing historic utility data (typically 12 to 36 months) and benchmarking the facility's Energy Use Intensity (EUI) against similar buildings (such as through the EPA's ENERGY STAR Portfolio Manager). The purpose of the PEUA is to establish a baseline energy consumption, determine the potential for energy savings, and prioritize which buildings in a portfolio warrant a more detailed investigation. The PEUA does not typically involve a site visit.

ASHRAE Level I: Walk-Through Analysis

The Level I audit, often referred to as a 'Walk-Through Analysis,' builds upon the PEUA. Its primary objective is to identify glaring inefficiencies and prioritize further energy engineering efforts. It is designed to be a quick, low-cost assessment.

Key Characteristics of Level I:

• Scope: Brief site visit by an energy professional to assess the building envelope, lighting, HVAC systems, and operating schedules.
• Objective: Identify obvious 'low-hanging fruit' (e.g., lighting scheduling errors, visible leaks, uninsulated pipes) and low-cost/no-cost Energy Conservation Measures (ECMs).
• Analysis: Provides rough estimates of potential energy savings and costs. Financial analysis is rudimentary, often relying on simple payback periods.
• Deliverable: A short report detailing the identified low-cost/no-cost measures, a summary of utility data, and a list of potential capital improvements that merit a Level II or Level III investigation.

For the CEM exam, remember that Level I is not sufficient for securing financing for major capital projects. It is a screening tool to justify the expense of a more detailed audit.

ASHRAE Level II: Energy Survey and Analysis

The Level II audit is the standard energy audit and is what most facility managers expect when they request an energy assessment. It provides a detailed analysis of all practical ECMs that meet the owner's financial criteria.

Key Characteristics of Level II:

• Scope: In-depth site survey involving detailed data collection. It includes a thorough review of mechanical and electrical design drawings, equipment schedules, and operating logs.
• Objective: To evaluate building energy systems in detail and develop a comprehensive list of ECMs.
• Analysis: Requires detailed energy calculations to estimate the savings of each proposed ECM. Importantly, it includes an energy balance, which breaks down the total energy consumption by end-use (e.g., lighting, cooling, heating, plug loads). The estimated end-use consumption must reconcile closely with the actual utility bills (typically within 10%). Financial analysis includes detailed cost estimates and life-cycle cost analysis (LCCA) or return on investment (ROI) calculations.
• Deliverable: A comprehensive report outlining the energy balance, detailed descriptions of each ECM (including baseline and proposed conditions), estimated installation costs, projected energy and cost savings, and financial metrics.

Level II audits also identify capital-intensive measures that require more rigorous data collection and engineering analysis, deferring those to a Level III audit.

ASHRAE Level III: Detailed Analysis of Capital Intensive Modifications

The Level III audit, sometimes called an 'Investment Grade Audit' (IGA), focuses on potential capital-intensive projects identified during a Level II audit. This level of audit provides the detailed engineering and financial rigor required to secure funding for major infrastructure upgrades, often through Energy Savings Performance Contracts (ESPCs).

Key Characteristics of Level III:

• Scope: Involves intensive field data collection over an extended period. This includes deploying data loggers to measure sub-system energy consumption, temperature, humidity, and equipment runtimes over days or weeks.
• Objective: To provide highly accurate and reliable estimates of energy savings and project costs to minimize financial risk for investors or lenders.
• Analysis: Typically involves the creation of a calibrated hourly whole-building energy simulation model (using software like EnergyPlus or eQUEST). The model is calibrated to match historical utility data within strict tolerances (e.g., ASHRAE Guideline 14). Vendor quotes are often obtained for firm pricing rather than relying on standard cost estimating guides.
• Deliverable: An investment-grade report with highly detailed engineering calculations, validated vendor pricing, comprehensive risk assessments, and rigorous financial projections suitable for bank financing.

Comparing the Audit Levels

The Auditor's Mindset

A successful CEM understands that an energy audit is not just a technical exercise; it's a communication tool. The final report must translate complex engineering calculations into a compelling business case for facility owners and financial decision-makers. The auditor must always consider the operational requirements of the facility—ECMs must not compromise occupant comfort, product quality, or safety. Understanding the nuances between Level I, II, and III audits ensures that the right level of effort is applied to meet the specific goals of the client and the constraints of the budget.