Study guide
3.1 Energy Audit Methodologies: ASHRAE Level I, II, and III Audit Scopes
AEE Certified Energy Manager CEM
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1 Chapter 1: Energy and Sustainability Policies, Codes, and Standards
1.1 Federal and State Energy Policies, Decarbonization Targets, and ESG Reporting 1.2 Building Energy Codes: ASHRAE Standard 90.1, IECC, and Compliance Paths 1.3 Energy Management Systems: ISO 50001, ENERGY STAR Benchmarking, and Portfolio Manager
2 Chapter 2: Energy Rates, Tariffs, and Supply Options
2.1 Utility Rate Structures: Volumetric vs. Demand Charges, Time-of-Use (TOU), and Real-Time Pricing 2.2 Demand Charges, Ratchets, Peak Shaving, and Power Factor Penalties 2.3 Energy Procurement, Deregulated Markets, Supply Contracts, and Green Tariffs 2.4 Demand-Side Management, Load Curtailment, and Transportation Energy Efficiency
3 Chapter 3: Energy Audits and Instrumentation
3.1 Energy Audit Methodologies: ASHRAE Level I, II, and III Audit Scopes 3.2 Audit Instrumentation, Data Loggers, Metering Accuracy, and Safety (PPE) 3.3 Baseline Energy Data, Utility Bill Disaggregation, and ECM Identification 3.4 Energy Modeling, Simulation, Digital Tools, and Performance Indicators
4 Chapter 4: Energy Accounting and Economics
4.1 Energy & Power Units (kWh, kW, Therms, MMBtu, Joules) and Conversion Calculations 4.2 Financial Metrics: Simple Payback Period, Return on Investment (ROI), and LCCA 4.3 Time Value of Money: Net Present Value (NPV), Internal Rate of Return (IRR), and Escalation 4.4 Advanced Financial Evaluation: Annual Worth, SIR, Depreciation, and Interest Formulas
5 Chapter 5: Electrical Power Systems and Motors
5.1 Electrical Fundamentals: Single/Three-Phase Power, Apparent/Real/Reactive Power, and Power Factor 5.2 Electric Motors: Efficiency Classes, Loading Calculations, NEMA Premium, and Losses 5.3 Variable Frequency Drives (VFDs), Affinity Laws, and Electrical Harmonics
6 Chapter 6: Lighting Systems
6.1 Lighting Fundamentals: Photometric Quantities (Lumens, Lux, Foot-Candles, CRI, CCT) and Efficacy 6.2 Lighting Technologies & Retrofits: LED Systems, Fluorescent/HID Replacement, and LPD 6.3 Lighting Controls: Occupancy/Vacancy Sensors, Daylight Harvesting, Dimming, and Task Tuning
7 Chapter 7: HVAC Systems and Building Envelope
7.1 HVAC Fundamentals & Psychrometrics: Dry-Bulb, Wet-Bulb, Dew Point, Relative Humidity, and Enthalpy 7.2 Cooling and Heating Equipment: Chillers (COP, kW/ton, EER, SEER), Heat Pumps, and Boilers 7.3 Air and Water Distribution: AHUs, VAV vs. CAV, Pumping Systems, Fans, and Economizers 7.4 Building Envelope: Heat Transfer (U-factor, R-value, SHGC), Infiltration, and Thermal Insulation 7.5 Building Envelope Calculations: Degree-Days, Solar Heat Gain, and Passive Design 7.6 Refrigerants, Cooling Towers, and Specialized HVAC Technologies (Absorption, VRF, Chilled Beams)
8 Chapter 8: Building Automation, Controls, and Artificial Intelligence Systems
8.1 Building Automation Systems (BAS) Architecture, BACnet, Modbus, and DDC Loops 8.2 Energy Control Strategies: Temperature/Pressure Resets, Night Setback, and Deadbands 8.3 Fault Detection & Diagnostics (FDD), Energy Analytics, and AI Optimization 8.4 IoT, Cloud-Based BAS, Expert Systems, and Cyber-Security
9 Chapter 9: Energy Storage Systems
9.1 Battery Energy Storage Systems (BESS): Technologies, Capacity, Efficiency, and Safety 9.2 Thermal Energy Storage (TES): Chilled Water, Ice Storage, and Phase Change Materials 9.3 Storage Dispatch Strategies, Tariff Integration, Peak Shaving, and Microgrid Integration
10 Chapter 10: Boiler and Steam Systems
10.1 Boiler Fundamentals & Efficiency: Combustion Efficiency, Excess Air, and Stack Losses 10.2 Steam Distribution & Traps: Steam Trap Types, Failure Modes, Testing, and Insulation 10.3 Condensate Recovery, Boiler Blowdown Control, and Waste Heat Recovery
11 Chapter 11: Distributed Generation and Renewable Energy Systems
11.1 Solar Photovoltaic (PV) and Wind Energy Systems: Design, Inverters, and Capacity Factor 11.2 Combined Heat and Power (CHP) / Cogeneration: Thermal Efficiency and System Sizing 11.3 Grid Interconnection, Net Metering, Islanding, and Microgrid Resilience 11.4 Biomass, Geothermal, Hydropower, Solar Thermal, and Waste-to-Energy Systems
12 Chapter 12: Industrial Systems
12.1 Compressed Air Systems: Efficiency, Pressure Drop, Leak Management, and Receiver Storage 12.2 Industrial Process Heating, Cooling Towers, and Industrial Refrigeration 12.3 Production-Normalized Energy Metrics, Pumping System Optimization, and Process Integration
13 Chapter 13: Operations, Maintenance, and Commissioning
13.1 Preventive, Predictive, and Reliability-Centered Maintenance Strategies 13.2 Building Commissioning: Existing Building Commissioning (EBCx) & Retro-Commissioning (RCx) 13.3 Savings Persistence, Continuous Commissioning, Sensor Calibration, and Alarms 13.4 Quantifying O&M Losses: Compressed Air Leaks, Steam Traps, Boiler Scale, and Group Relamping 13.5 CMMS, Water Treatment, and Human Behavior in Energy Management
14 Chapter 14: Energy Savings Performance Contracting and Measurement & Verification
14.1 Energy Savings Performance Contracting (ESPC), ESCO Roles, and Financing Models 14.2 Measurement and Verification (M&V): IPMVP Options A, B, C, and D 14.3 Baselines, Weather Normalization, Non-Routine Adjustments, and M&V Reporting
3.1 Energy Audit Methodologies: ASHRAE Level I, II, and III Audit Scopes
Key Takeaways Explain This Topic AI
ASHRAE Level I is a Walk-Through Analysis focusing on low-cost/no-cost measures and identifying potential capital projects.
ASHRAE Level II is an Energy Survey and Analysis providing detailed energy calculations and financial analysis of all practical ECMs.
ASHRAE Level III is a Detailed Analysis of Capital Intensive Modifications involving rigorous engineering modeling and vendor pricing.
The preliminary energy use analysis (PEUA) establishes the baseline performance benchmark for all audit levels.
Energy audits must systematically follow a scope of work defined by ASHRAE Procedures for Commercial Building Energy Audits.
Last updated: July 2026
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
- Feature Level I (Walk-Through) Level II (Survey & Analysis) Level III (Detailed Analysis)
- Site Visit Time Hours Days Weeks (including data logging)
Data Collection Visual inspection, basic spot measurements Detailed inventory, spot measurements, basic logging Extensive sub-metering and long-term data logging
Energy Breakdown General estimates Detailed energy balance reconciling with bills Calibrated hourly computer simulation
- Cost Estimates Rough rules of thumb Standard estimating guides (e.g., RSMeans) Firm vendor quotes
- Financial Analysis Simple Payback LCCA, ROI, NPV Rigorous investment grade financial analysis
Primary Use Prioritizing buildings, finding quick wins Standard energy management planning Securing major project financing (ESPC)
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.