Home Energy Audit Guide

A home energy audit, also called a home energy assessment, looks at how your home uses and loses energy. Instead of guessing whether you need more insulation, new windows, air sealing, HVAC work, or another improvement, an audit helps identify where the biggest opportunities may be.

A professional assessment can combine a visual inspection with diagnostic testing, a review of energy bills, and an evaluation of insulation, air leakage, heating and cooling equipment, moisture, and ventilation. ENERGY STAR describes the process as a whole-home evaluation that leads to a prioritized list of recommended improvements.

This guide explains what a home energy audit includes, what professional testing can reveal, what you can check yourself, and how to use the results when planning energy-efficiency improvements.

What Is a Home Energy Audit?

A home energy audit is an evaluation of a home’s energy performance. The goal is to identify where energy is being lost or used inefficiently and determine which improvements are likely to make the most sense.

The terms home energy audit, home energy assessment, and home performance assessment are often used for similar services. ENERGY STAR defines a home energy assessment as an evaluation based on inspections, diagnostic testing, data collection, analysis, and reporting that identifies opportunities to improve energy efficiency.

An audit is different from simply having an insulation contractor look in the attic or an HVAC company inspect the furnace. Those evaluations can be useful, but an energy audit takes a broader view of how different parts of the home interact.

That whole-house perspective matters because a comfort or energy problem may have more than one cause. A cold upstairs bedroom, for example, could involve insulation levels, air leakage, duct performance, HVAC balancing, or several of those factors at once.

What Does a Home Energy Audit Check?

The exact scope depends on the auditor, program, home, and type of assessment. A comprehensive professional audit generally examines both the building enclosure and the systems that heat, cool, ventilate, and supply the home.

Common areas include:

Insulation

The assessor may inspect accessible insulation in areas such as:

• Attics
• Kneewalls
• Basement ceilings
• Crawl spaces
• Rim joists
• Accessible wall cavities

The goal is not only to determine whether insulation exists. Distribution, gaps, compression, installation quality, and its relationship to the home’s thermal boundary can also affect performance.

If you want a deeper explanation of how insulation resistance is measured, see the R-value guide.

Air Leakage

Small openings between conditioned living space and attics, crawl spaces, garages, wall cavities, and the outdoors can allow uncontrolled air movement.

Common leakage areas include:

• Plumbing and wiring penetrations
• Recessed lights
• Attic hatches
• Chimney and flue penetrations
• Window and door assemblies
• Rim joists
• Open framing cavities
• Gaps around ductwork and registers

Insulation and air sealing perform different jobs, which is why both may need to be considered. Learn more about air sealing vs. insulation.

Heating and Cooling Systems

An assessment may look at the condition and operation of:

• Furnaces
• Boilers
• Heat pumps
• Central air conditioners
• Duct systems
• Thermostats
• Distribution systems

A high energy bill does not automatically mean the HVAC system needs to be replaced. Building-envelope problems can increase how hard heating and cooling equipment has to work.

Ductwork

Ducts may be checked for:

• Leakage
• Disconnected sections
• Damaged insulation
• Poorly sealed joints
• Runs through unconditioned spaces
• Distribution problems

Some professional auditors use separate duct-pressure testing when more precise leakage information is needed.

Windows and Doors

Windows and doors may be inspected for air leakage, damaged weatherstripping, poorly sealed frames, or other conditions.

They are only one part of the building enclosure, however. Replacing windows before identifying larger attic, crawl-space, duct, or air-sealing problems can lead to spending money without addressing the home’s main source of energy loss.

Moisture and Ventilation

A thorough assessment may also look for moisture concerns and whether ventilation is functioning appropriately. ENERGY STAR includes leaks, moisture problems, and ventilation issues among the conditions that may be evaluated during diagnostic testing.

These issues are important because tightening a home without considering moisture and ventilation can create unintended indoor-air-quality or durability problems.

For a closer look at that relationship, see ventilation and moisture.

Energy Bills

Professional assessments often include a review of historical utility use. ENERGY STAR identifies an energy-bill review as part of a home performance assessment when records are available.

Bills can provide useful context, but they do not diagnose a house by themselves. Energy consumption also depends on climate, thermostat settings, household size, appliance use, and occupant habits.

What to Expect During a Professional Home Energy Audit

A comprehensive assessment usually has several stages.

1. Homeowner Interview

The auditor should first understand what you are experiencing.

Useful information may include:

• Rooms that are consistently too hot or cold
• Drafts
• High or increasing energy bills
• Humidity or condensation
• Ice dams
• Musty areas
• Previous insulation work
• HVAC replacements or additions
• Areas of the home that are difficult to heat or cool

ENERGY STAR includes the homeowner interview as a standard part of a home performance assessment because comfort concerns and living patterns provide useful context for the technical evaluation.

2. Energy-Use Review

If possible, have recent electricity, natural gas, propane, heating-oil, or other energy records available.

The auditor may look for seasonal patterns or unusually high consumption and compare that information with what is found during the home inspection.

3. Visual Inspection

The auditor may examine the home’s exterior, interior, building enclosure, insulation, and mechanical systems.

Accessible attics, crawl spaces, basements, utility areas, and mechanical equipment can provide important clues about how the home is performing.

4. Diagnostic Testing

Depending on the service, the assessment may include diagnostic tools such as:

• Blower door testing
• Infrared imaging
• Duct leakage testing
• Combustion-safety testing
• Moisture measurements

Not every audit includes every test. Ask what is included before scheduling the assessment.

5. Recommendations

After the evaluation, you should receive findings explaining what was discovered and what improvements should be considered.

ENERGY STAR recommends that a home performance assessment produce a prioritized list based on factors such as health and safety, comfort, and overall cost-benefit.

A useful report should help distinguish between significant problems and lower-priority improvements.

Diagnostic Tests Used in Home Energy Audits

Diagnostic equipment helps reveal conditions that may not be obvious during a visual inspection.

Blower Door Test

A blower door is one of the most recognizable tools used during professional energy audits.

A calibrated fan is temporarily installed in an exterior doorway. The fan changes the pressure inside the house, allowing the auditor to measure overall air leakage and locate places where outside air is entering through cracks and openings.

DOE describes blower door testing as a method for measuring the airtightness of a home.

A blower door can help answer two different questions:

1. How leaky is the house overall?
2. Where are important leakage pathways located?

That makes the test useful when planning air-sealing work.

Infrared or Thermographic Inspection

An infrared camera detects surface-temperature differences that cannot be seen with the naked eye.

Under suitable conditions, temperature patterns may help an experienced assessor identify:

• Missing insulation
• Uneven insulation
• Air leakage
• Thermal bridging
• Unexpected heat flow

DOE notes that infrared imaging and blower door testing are often used together during home energy assessments.

An infrared image still needs interpretation. A temperature difference does not automatically prove that insulation is missing, so results should be considered together with the physical inspection and other testing.

Duct Leakage Testing

Where duct leakage is a concern, an auditor may use specialized equipment to pressurize the duct system and measure leakage.

Testing can be particularly useful when ducts run through attics, crawl spaces, garages, or other areas outside the conditioned part of the house.

Health and Safety Testing

A comprehensive home-performance assessment may include checks related to combustion appliances, ventilation, moisture, or other health and safety conditions before extensive air sealing is recommended.

This is one reason whole-house planning matters. Making a home tighter changes air movement, so combustion safety and ventilation should be considered when applicable.

Can You Do a DIY Home Energy Audit?

You can perform a basic energy assessment yourself.

A DIY evaluation will not provide the same measurements as professional diagnostic testing, but it can help you understand your home and identify obvious areas worth investigating.

ENERGY STAR recommends several homeowner checks for insulation and air leakage while noting that a comprehensive professional audit can provide a more detailed evaluation and identify potential safety issues.

Check Your Attic Insulation

If the attic is safely accessible, look at whether insulation:

• Covers the attic floor evenly
• Has obvious low areas
• Has been compressed or moved
• Leaves joists clearly exposed
• Has gaps around penetrations
• Appears damaged by moisture

Do not assume that insulation depth alone tells the entire story. The insulation type, installed condition, and recommended R-value for the climate all matter.

ENERGY STAR provides specific attic-insulation inspection guidance and recommends checking both depth and distribution.

Look for Air-Leakage Paths

Visually inspect common transitions and penetrations, including:

• Attic access doors
• Plumbing penetrations
• Wiring holes
• Recessed fixtures
• Window and door frames
• Exterior wall penetrations
• Rim joists
• Fireplace surrounds where accessible and safe

ENERGY STAR notes that cracks and gaps in the home’s enclosure are common signs that air sealing may be needed.

Review Your Energy Bills

Compare at least a year of bills when possible.

Look for patterns rather than concentrating on a single month. Weather, utility-rate changes, household occupancy, and thermostat settings can all affect energy use.

Note Comfort Problems

Walk through the home and write down:

• Rooms that feel unusually cold in winter
• Rooms that overheat in summer
• Drafty areas
• Floors that feel especially cold
• Humidity or condensation problems
• Areas with musty odors
• Spaces where HVAC airflow seems weak

These observations can make a later professional assessment more useful.

Inspect Accessible Ductwork

Where ducts are visible, check for:

• Loose connections
• Torn or missing insulation
• Crushed flexible ducts
• Open seams
• Disconnected sections

Avoid taking apart duct systems unless you understand the system and can do so safely.

Know When Not to Disturb Materials

Older homes can contain materials that should not be disturbed casually.

ENERGY STAR specifically cautions homeowners that vermiculite attic insulation may contain asbestos and recommends not disturbing it unless appropriate testing has established that it is safe.

If you encounter unfamiliar insulation, damaged materials, suspected asbestos, mold, unsafe electrical conditions, or difficult attic access, stop the DIY inspection and seek appropriate professional help.

DIY vs. Professional Home Energy Audit

DIY & Professional Home Energy Audits

Topic	DIY Audit	Professional Audit
Visual inspection	Yes	Yes
Utility bill review	Yes	Usually
Basic insulation check	Yes	Yes
Visual air leak check	Yes	Yes
Calibrated blower door	No	May be included
Infrared imaging	Limited without equipment and training	May be included
Duct leakage measurement	No	May be included
Safety testing	Limited	May be included
Prioritized written recommendations	Self-developed	Typically included
Best suited for	Initial screening and homeowner education	Detailed diagnosis and upgrade planning

How Much Does a Home Energy Audit Cost?

There is no single nationwide price for a professional home energy audit.

The amount you pay can depend on:

• Home size
• Location
• Scope of the assessment
• Number of diagnostic tests included
• Whether duct testing is included
• Whether the assessment is offered through a utility or efficiency program
• Whether follow-up testing is part of the service

Some utilities, state programs, municipalities, or efficiency programs may provide discounted or subsidized assessments. ENERGY STAR recommends checking with local utilities and programs because assistance for professional assessments and related improvements may be available in some areas.

When comparing prices, look at the scope of work, not just the advertised audit fee.

A low-cost walk-through and a comprehensive diagnostic assessment are not necessarily equivalent services.

Questions to Ask About the Price

Before scheduling an audit, ask:

• Is a blower door test included?
• Is infrared imaging included?
• Is duct leakage testing included?
• Are combustion or safety checks included where applicable?
• Will I receive a written report?
• Will recommendations be prioritized?
• Is follow-up testing available?
• Does the auditor also sell the improvements being recommended?
• Are utility or local-program discounts available?

Understanding what you are purchasing makes different audit quotes easier to compare.

How to Understand Your Home Energy Audit Results

A long list of recommendations does not mean every project should be completed immediately.

The real value of an audit is helping establish priorities.

Start With Health, Safety, and Moisture Issues

Conditions involving:

• Combustion safety
• Active moisture problems
• Significant ventilation deficiencies
• Electrical hazards
• Suspected hazardous materials

may need attention before energy-efficiency work proceeds.

Identify the Thermal Boundary

The thermal boundary is the separation between conditioned living space and areas outside that space.

Before adding insulation, it helps to understand where that boundary should be and whether the insulation and air barrier are aligned.

See how the thermal boundary works for a more detailed explanation.

Address Important Air Leakage

Air sealing is often performed before or alongside insulation because insulation alone does not reliably stop uncontrolled air movement.

An audit can help identify the leakage areas that deserve the most attention rather than relying only on obvious drafts around windows and doors.

Evaluate Insulation

Once moisture and air-leakage concerns are understood, assess whether insulation is:

• Present
• Adequate for the application
• Evenly installed
• Dry and undamaged
• Properly aligned with the home’s thermal boundary

Insulation upgrades should be based on the condition of the existing assembly rather than simply adding material everywhere.

Consider Mechanical Systems in Context

Heating and cooling equipment should be evaluated as part of the home as a whole.

If substantial air sealing and insulation work is planned, heating and cooling loads may change. That can affect future equipment decisions.

Prioritize by Impact and Practicality

A useful plan often separates recommendations into categories such as:

Higher priority

• Safety corrections
• Moisture problems
• Major air leakage
• Missing or severely inadequate insulation

Planned improvements

• Additional insulation
• Duct sealing or insulation
• Ventilation improvements
• Mechanical-system upgrades

Lower-priority or situational projects

• Improvements with relatively small expected impact
• Cosmetic work
• Equipment that is operating adequately but may eventually need replacement

The exact order depends on the home.

What an Energy Audit Can Tell You About Insulation

An energy audit does more than answer, “Do I need more insulation?”

It can help determine:

• Whether insulation is missing in important areas
• Whether insulation is uneven
• Whether air is bypassing the insulation
• Whether the insulated boundary is located in the right place
• Whether moisture has damaged existing material
• Whether ductwork passing through unconditioned space needs attention
• Whether insulation should be coordinated with air sealing

That context can prevent a common mistake: treating insulation as an isolated product instead of one part of the home’s enclosure.

For more background, see how insulation saves energy.

When Does a Home Energy Audit Make Sense?

An audit can be particularly useful when you have a problem but do not know its cause.

Examples include:

• Energy bills that seem unusually high
• Rooms that are difficult to keep comfortable
• Major temperature differences between floors
• Persistent drafts
• Cold floors
• Ice dams
• Planned insulation upgrades
• Planned HVAC replacement
• A major renovation
• An older home with an uncertain upgrade history
• Multiple contractors recommending different solutions

An assessment can also be worthwhile before committing to several expensive upgrades at once.

It is generally easier to develop an effective plan when you understand the house first.

How to Choose a Home Energy Auditor

Not all services marketed as “energy audits” include the same level of testing.

Ask potential auditors about their training, process, equipment, reporting, and whether they participate in recognized home-performance programs.

Ask What the Assessment Includes

Request a clear description of:

• Areas inspected
• Diagnostic tests
• Safety testing
• Energy-use analysis
• Deliverables
• Report format
• Follow-up services

Ask About Qualifications

DOE recommends using trained home energy professionals, and federal home-performance programs support standardized training and work specifications for residential energy upgrades.

Depending on your location and program, auditors may hold certifications from recognized building-performance organizations or participate in utility or government-sponsored programs.

Ask Whether the Auditor Also Performs Upgrades

Some energy auditors are independent consultants. Others also perform insulation, HVAC, air-sealing, or other contracting work.

Neither model is automatically better.

If the company performing the assessment also sells the recommended improvements, ask for measurements, photographs, diagnostic results, and a clear explanation of why each project is being recommended.

Ask for a Sample Report

A good report should be understandable to a homeowner.

Look for:

• Identified problems
• Supporting observations or measurements
• Photographs when useful
• Recommended improvements
• Priorities
• Important safety considerations
• Enough explanation to understand why each recommendation was made

The report should help you make decisions even if you ultimately hire another company to complete the work.

Frequently Asked Questions