Home Energy Rating Assessment

What Does a Home Energy Rating Assessor Look For?

A home energy rating assessor looks for the building features and installed systems that influence how an existing home performs.

For an existing home, the assessment is not just a quick visual inspection. It involves collecting structured information about the dwelling, including the building fabric, orientation, windows, insulation, shading, heating and cooling, hot water, solar, batteries and comfort issues.

The aim is to understand how the home performs now, why it may feel uncomfortable or expensive to run, and what information is needed to support a reliable rating or upgrade pathway.

Why the assessor’s review matters

Existing homes are rarely as simple as a clean set of architectural drawings. A home may have been extended, re-roofed, renovated, insulated, fitted with solar or upgraded with new heating and cooling systems over many years.

The assessor’s role is to turn that real-world condition into structured assessment information. This means looking at both the visible parts of the dwelling and the available documentation that can support the rating.

For a broader explanation of the process, see How Does a NatHERS Existing Home Assessment Work?

The assessor looks at layout and orientation

The layout and orientation of a home influence how it receives sun, shade, wind and heat across the day and year. They also affect how rooms are heated, cooled and ventilated.

The assessor may record:

• dwelling type and number of storeys
• room layout and approximate zoning
• orientation of main living spaces
• exposure to sun and shade
• relationship between windows, rooms and outdoor spaces
• whether certain rooms are more exposed than others

This helps explain why some spaces may overheat, stay cold or require more heating and cooling than others.

The assessor looks at the building fabric

The building fabric is the physical shell of the home. It includes the parts of the dwelling that separate inside from outside and influence heat gain, heat loss and comfort.

The assessor may consider:

• roof and ceiling construction
• external wall construction
• floor and subfloor conditions
• construction materials
• thermal mass
• external doors
• visible gaps, draught paths or weak points
• areas affected by additions or renovations

This part of the assessment helps show how much the home relies on mechanical systems to remain comfortable.

The assessor looks for insulation information

Insulation is one of the most important performance factors in many existing homes, but it is not always easy to confirm. Older homes may have no records, partial insulation or insulation added during previous upgrades.

The assessor may look for information about:

• ceiling insulation
• roof insulation
• wall insulation
• floor insulation
• insulation added during renovations
• visible insulation in accessible areas
• insulation product information, where available
• areas where insulation is missing or uncertain

If insulation cannot be safely viewed or documented, the assessor may need to record the uncertainty and apply the relevant assessment pathway rules.

The assessor looks at windows, glazing and shading

Windows can have a large effect on comfort and energy use. They influence solar heat gain, heat loss, daylight, ventilation and how rooms respond to different seasons.

The assessor may review:

• window size and location
• orientation of windows
• glazing type, where identifiable
• frame type
• eaves, awnings and verandahs
• external blinds or shading devices
• nearby buildings, fences or landscape shading
• rooms affected by glare or overheating

This information helps connect the home’s design and exposure to its heating and cooling needs.

The assessor looks at heating and cooling systems

Heating and cooling systems influence how much energy the home uses to remain comfortable. The assessor may need to record the type of systems installed and how they serve the dwelling.

Relevant details may include:

• air conditioning type
• heating system type
• system locations
• zoned or whole-home systems
• approximate system age, if known
• model information or labels
• whether systems are still in use
• rooms that remain uncomfortable despite system use

This does not mean the assessor is only checking appliances. The performance of the building fabric still has a major influence on how hard those systems need to work.

The assessor looks at hot water and major energy systems

Depending on the assessment pathway, the assessor may also collect information about major fixed systems that affect whole-of-home energy performance.

This may include:

• hot water system type
• lighting
• major fixed appliances
• pool or spa equipment, where relevant
• recent electrification upgrades
• system labels or model details
• known issues with system performance

These systems help complete the picture of how the home uses energy beyond heating and cooling alone.

The assessor looks at solar and batteries, where relevant

Solar PV and batteries may influence whole-of-home energy performance, depending on the assessment pathway.

Useful information may include:

• solar PV system size, if known
• inverter details
• battery details, if installed
• installation date, if known
• photos of system labels
• whether the system is currently operating

Solar and batteries can reduce grid energy use, but they do not replace the need to understand the building fabric, comfort and heating and cooling demand.

The assessor asks about comfort issues

Comfort issues can help explain how the home is experienced in daily life. They do not replace assessment data, but they provide useful context.

Useful comfort information may include:

• rooms that overheat in summer
• rooms that stay cold in winter
• areas affected by draughts
• rooms with harsh sun or glare
• rooms that are difficult to heat or cool
• condensation, dampness or moisture concerns
• areas where the home relies heavily on mechanical heating or cooling

This information helps connect the rating to the lived reality of the home, rather than only treating it as a technical exercise.

The assessor identifies what is known and what is uncertain

One of the most important parts of an existing home assessment is identifying the difference between known information and uncertain information.

Some details may be confirmed from plans, labels, receipts, observations or homeowner records. Other details may be unknown, hidden or only partly visible.

This is why original plans are helpful, but not always available. For that specific question, see Can You Get a Home Energy Rating Without Original Plans?

What is the assessor not looking for?

A home energy rating assessment is not the same as a general building inspection, pest inspection, structural engineering review or electrical safety audit.

The assessor is focused on energy performance, comfort, relevant building features and energy-related systems. If structural, safety, moisture or electrical concerns are identified, those may need to be referred to the appropriate specialist.

This distinction helps avoid confusion about what a home energy rating is designed to do.

How to prepare before the assessor reviews the property

You do not need perfect documentation before making an enquiry, but preparation can make the process smoother.

Useful information may include:

• property address
• available floor plans or drawings
• renovation or extension history
• photos of the home
• known insulation information
• heating and cooling system details
• hot water system details
• solar PV or battery details
• known comfort issues
• reason for requesting the rating

For a full preparation checklist, see What Information Do You Need for a Home Energy Rating?

FAQs

What does a home energy rating assessor look for?

A home energy rating assessor looks for the physical features and systems that influence energy performance, comfort and upgrade potential. This may include layout, orientation, insulation, windows, shading, heating and cooling, hot water, lighting, appliances, solar, batteries and comfort issues.

Does a home energy rating assessor check insulation?

Yes. Insulation is an important part of many home energy rating assessments. The assessor may review ceiling, roof, wall or floor insulation where this information is visible, documented or able to be assessed under the relevant pathway.

Does a home energy rating assessor check windows?

Yes. Windows, glazing and shading can significantly affect heat gain, heat loss, daylight and comfort. An assessor may review window size, orientation, glazing type, frame type and external shading.

Will the assessor look at heating and cooling systems?

Yes. Heating and cooling systems are usually relevant because they affect energy use and comfort. The assessor may record system type, location, age, efficiency information and how the systems serve the dwelling.

Does the assessor need access to every room?

For an existing home assessment, access to relevant rooms and areas may be needed so the dwelling layout, windows, systems and visible building features can be recorded. Exact access requirements depend on the assessment pathway and property.

Can an assessor complete a rating without original plans?

Original plans are helpful but not always available for existing homes. Depending on the pathway, the assessor may use available documentation, site data, photos, observations and permitted assumptions where information is incomplete.

Assessment Preparation

Preparing for a home energy rating?

Send your property details, available plans and photos so Certified Energy can review the likely assessment pathway.

Send property details for review