The process can examine electricity, natural gas, heating, cooling, lighting, ventilation, building controls, water heating, and other energy-consuming systems. Depending on the building and audit level, the assessment may range from a basic review of utility data to detailed measurements and engineering analysis.

Energy audits are commonly used for commercial buildings, industrial facilities, institutional properties, healthcare facilities, educational buildings, and large residential properties.

A well-planned assessment can help facility managers understand energy-use patterns, identify inefficient equipment or operating practices, and prioritize potential improvements.

What Is a Building Energy Audit?

A building energy audit evaluates energy consumption and building-system performance to identify potential efficiency improvements.

A typical assessment may review:

• Historical utility consumption

• Building occupancy and operating schedules

• HVAC equipment

• Lighting systems

• Building envelope

• Heating and cooling controls

• Ventilation systems

• Domestic hot-water equipment

• Motors and pumps

• Refrigeration equipment

• Energy-management systems

• On-site generation or storage

• Maintenance and operating practices

The depth of the assessment depends on the facility's objectives, available information, building complexity, and applicable standards.

Levels of Energy Assessment

Energy audits can be performed at different levels of detail.

Preliminary Energy Assessment

A preliminary review generally examines utility bills, building characteristics, operating schedules, and readily available information.

It can help identify obvious areas for further investigation without requiring extensive field measurements.

Detailed Energy Audit

A detailed audit typically involves site inspections, equipment inventories, measurements, operational analysis, and evaluation of potential efficiency measures.

The auditor may develop energy-use estimates for major building systems and compare them with expected performance.

Investment-Grade Assessment

A more detailed financial and engineering assessment may be appropriate when a facility is considering significant capital improvements.

This type of analysis can include detailed energy modeling, measurement plans, project assumptions, implementation considerations, and financial analysis.

The terminology and scope can vary between organizations, so the audit objectives should be clearly defined before work begins.

Energy Assessment Process

A building energy audit commonly follows several stages.

1. Collect building information

The assessment begins with information about the building, equipment, occupancy, operating schedules, utility accounts, and previous improvement projects.

2. Review energy consumption

Historical electricity and fuel data can reveal seasonal patterns, unusual consumption, demand peaks, and changes in facility performance.

3. Conduct a site assessment

An on-site inspection allows the auditor to examine equipment, controls, lighting, insulation, air leakage, operating conditions, and other factors that may not appear in utility records.

4. Identify efficiency measures

Potential improvements are identified based on observed conditions and energy-use patterns.

5. Evaluate opportunities

Each potential measure can be evaluated for technical feasibility, energy impact, implementation requirements, expected lifespan, and financial considerations.

6. Prioritize improvements

Facilities can prioritize measures according to energy impact, operational importance, implementation complexity, available capital, and organizational objectives.

Major Building Systems Reviewed

HVAC and Building Controls

Heating, ventilation, and air-conditioning systems can represent a significant portion of building energy consumption.

An audit may examine:

• Equipment efficiency

• Thermostat settings

• Operating schedules

• Variable-speed drives

• Airflow

• Chilled-water systems

• Boilers

• Heat pumps

• Economizer operation

• Building automation controls

Poor scheduling or inappropriate control settings can increase energy consumption even when equipment itself is functioning correctly.

Lighting

Lighting assessments may examine fixture types, operating hours, controls, occupancy sensors, daylight controls, and lighting levels.

LED technology and automated controls can be considered where appropriate, although the suitability of an improvement depends on the existing system and building requirements.

Building Envelope

The building envelope includes roofs, walls, windows, doors, insulation, and other components separating conditioned areas from the outdoor environment.

An assessment may look for:

• Air leakage

• Inadequate insulation

• Window performance

• Door infiltration

• Roof conditions

• Solar heat gain

Envelope improvements can affect heating and cooling loads and may also influence occupant comfort.

Motors, Pumps, and Industrial Equipment

Commercial and industrial facilities may have substantial energy use from motors, pumps, compressors, fans, conveyors, and process equipment.

Auditors can examine equipment loading, operating schedules, control methods, maintenance conditions, and opportunities for improved system operation.

Energy Efficiency Measures

Potential measures vary significantly by building.

Common categories include:

An audit should evaluate measures based on the specific building rather than assuming that every facility will benefit from the same technology.

Energy Benchmarking

Energy benchmarking compares a building's energy performance with historical performance or comparable buildings.

Common data points include:

• Annual energy consumption

• Electricity demand

• Fuel consumption

• Floor area

• Occupancy

• Operating hours

• Weather conditions

• Energy-use intensity

In the United States, the ENERGY STAR Portfolio Manager platform is widely used for tracking and benchmarking building energy and water information.

Benchmarking can provide a useful starting point, but unusual building characteristics should be considered when interpreting comparisons.

Energy Modeling and Building Analysis

Energy modeling can provide a more detailed understanding of how building systems interact.

Models can evaluate factors such as:

• Weather conditions

• Building geometry

• Occupancy schedules

• HVAC performance

• Lighting loads

• Equipment loads

• Building-envelope characteristics

• Control strategies

Modeling can be especially useful when evaluating major renovation or new-building scenarios.

However, model results depend on the quality of the assumptions and input data.

Recent U.S. Energy-Efficiency Considerations

U.S. building energy policy continues to involve federal programs, state requirements, utility initiatives, building codes, and local efficiency programs.

The U.S. Department of Energy (DOE) develops building energy-efficiency resources and supports building-performance research and programs.

The Inflation Reduction Act also expanded federal incentives and funding mechanisms related to energy efficiency, electrification, and building improvements. Eligibility, amounts, deadlines, and applicable requirements can vary by program and property type.

State and local requirements can differ substantially. Some jurisdictions also use building-performance standards, benchmarking requirements, energy disclosure rules, or specific building-code provisions.

Facilities should verify current federal, state, and local requirements before planning an energy project.

Laws, Standards, and Planning Considerations

Energy audits may involve several standards and regulatory considerations.

Relevant resources can include:

• U.S. Department of Energy building-efficiency guidance

• ENERGY STAR Portfolio Manager

• ASHRAE energy-audit and building-performance resources

• International Energy Conservation Code provisions where adopted

• Local building energy codes

• State energy-efficiency requirements

• Utility energy-efficiency programs

• Federal tax-credit and incentive guidance

Requirements differ according to building type, jurisdiction, project scope, and applicable program rules.

Tools and Resources

Useful resources for building energy assessment include:

• Utility interval and billing data

• Building automation system records

• Energy meters and submeters

• Thermal imaging equipment

• Electrical measurement equipment

• HVAC diagnostic instruments

• ENERGY STAR Portfolio Manager

• DOE building-efficiency resources

• ASHRAE guidance

• Building energy modeling tools

The appropriate tools depend on the depth and objectives of the assessment.

Facility Energy Planning

An energy audit becomes more useful when its findings are incorporated into a broader facility plan.

A facility energy plan can establish:

1. Baseline energy performance.

2. Major energy-use categories.

3. Operational improvement opportunities.

4. Equipment upgrade priorities.

5. Building-envelope priorities.

6. Monitoring and measurement requirements.

7. Implementation timelines.

8. Performance-tracking methods.

9. Long-term capital planning.

Facilities can also establish performance indicators to monitor whether implemented measures are producing the expected operational results.

FAQs

1. What is a building energy audit?

A building energy audit is a structured assessment of a facility's energy consumption, equipment, operating conditions, and building systems to identify potential efficiency improvements.

2. What does an energy audit examine?

Depending on its scope, an audit can examine utility consumption, HVAC systems, lighting, building-envelope conditions, controls, motors, pumps, refrigeration, water heating, and operating practices.

3. How often should a building receive an energy assessment?

There is no single interval that applies to every facility. Larger buildings or facilities with significant energy use may benefit from periodic assessments, particularly after major equipment changes, renovations, occupancy changes, or significant shifts in energy consumption.

4. Can an energy audit identify HVAC efficiency opportunities?

Yes. HVAC equipment, controls, schedules, airflow, heating and cooling loads, and operating conditions are commonly reviewed during building energy assessments.

5. Is energy benchmarking the same as an energy audit?

No. Benchmarking primarily compares and tracks energy performance, while an energy audit involves a deeper assessment of building systems and potential efficiency measures.

Conclusion

A building energy audit provides a structured way to understand how a facility consumes energy and where operational or equipment improvements may be appropriate.

A useful assessment combines utility-data analysis, building inspection, equipment evaluation, controls review, benchmarking, and careful consideration of potential efficiency measures.

For facility managers, the most valuable outcome is not simply a list of technologies. It is a practical understanding of energy performance that can support maintenance decisions, capital planning, building improvements, and long-term facility management.