Home Energy Rating
A home energy rating measures how a dwelling performs as a home, not just how much energy appears on a bill.
For existing homes, the assessment may look at the building fabric, thermal comfort, windows, insulation, heating and cooling, hot water, solar, batteries and potential upgrade opportunities.
The purpose is to help homeowners, buyers, sellers, landlords and project teams understand how an established dwelling performs now, and what may improve its comfort and energy efficiency over time.
Quick Answer
A home energy rating measures how an existing dwelling performs for energy efficiency, comfort and likely energy use. It can help explain how well the home manages heat, cold, ventilation, appliances and energy demand.
The assessment may consider the building fabric, insulation, glazing, shading, orientation, heating and cooling, hot water, lighting, solar PV, batteries and other major energy-related features.
A rating is not simply a review of past energy bills. Bills can be affected by occupancy, behaviour and tariffs. A home energy rating is more focused on the home itself and how it is likely to perform.
A home energy rating is most useful when it looks at the home as a connected system. The walls, roof, floor, windows, shading and installed systems all affect comfort and energy demand.
For example, an efficient air conditioner may still struggle in a home with poor insulation, large unshaded windows or major draughts. Solar panels may reduce grid electricity use, but they do not necessarily solve overheating, winter heat loss or poor thermal comfort.
This is why a home energy rating for existing homes needs to consider both the building and the systems that support it.
The building fabric is the physical shell of the home. It includes the elements that separate inside from outside and influence how quickly heat enters or leaves the dwelling.
This may include:
Building fabric matters because it often determines how much heating or cooling the home needs before any appliance is even switched on.
Insulation is one of the main factors that can influence a home’s heating and cooling needs. A home with poor or missing insulation may lose heat quickly in winter and gain heat quickly in summer.
The assessment may consider insulation in:
In existing homes, insulation is not always easy to verify. The assessor may need to work with available plans, photos, site observations, renovation records and permitted assumptions.
Windows can have a major effect on comfort and energy use. They influence heat gain, heat loss, daylight, ventilation and exposure to sun.
A home energy rating may consider:
This is especially important in Australian homes where summer heat gain, winter heat loss and sun exposure can vary significantly by climate and orientation.
Thermal performance is one of the clearest parts of a home energy rating. It helps explain how much heating or cooling a home is likely to need to remain comfortable.
This is influenced by the design and construction of the home, not only by the appliances installed. A well-insulated, well-shaded home may need less active heating and cooling. A poorly sealed or poorly insulated home may need more energy to remain comfortable.
For existing homes, this can help explain why some rooms are difficult to heat, why certain spaces overheat, or why energy use remains high even after appliance upgrades.
Depending on the rating pathway, a home energy rating may also consider major fixed systems that contribute to household energy use.
These may include:
This is where the assessment starts to move beyond the shell of the building and into whole-of-home energy performance.
Solar PV and batteries can influence how much energy a home draws from the grid. Depending on the assessment pathway, they may be included as part of whole-of-home performance.
This does not mean that solar alone makes a home comfortable or efficient. A home with solar panels can still have poor insulation, overheating, draughts or high heating and cooling demand.
The rating is most useful when solar and batteries are considered alongside the building fabric and installed systems.
Many homeowners first become interested in a home energy rating because the home feels uncomfortable. Some rooms may overheat. Others may stay cold. Some areas may be draughty, damp or difficult to condition.
Useful comfort information may include:
This context helps connect the rating to the lived experience of the home.
One of the practical benefits of a home energy rating is that it can help identify where improvements may be most useful.
Possible upgrade areas may include:
The value is not just the list of possible upgrades. It is the sequencing. A rating can help homeowners understand whether the first step should be improving the building fabric, replacing systems, reviewing solar or planning upgrades as part of a renovation.
Energy bills can be useful context, but they do not tell the full story of the home. Bills are affected by household size, behaviour, tariffs, climate, appliance use and whether people work from home.
Two homes with similar bills may perform very differently. One may be efficient but heavily occupied. Another may be inefficient but used lightly. A home energy rating is intended to give a more structured understanding of the dwelling itself.
This is why the assessment focuses on physical features, systems and likely performance rather than treating a bill as the rating.
Different home energy rating pathways may have different inputs, certificate formats, software requirements and reporting outputs.
NatHERS Existing Homes, Residential Efficiency Scorecard and other home energy assessment approaches may not all present information in exactly the same way. The important point is to confirm which pathway applies before assuming what will be measured or reported.
For the NatHERS pathway, see What Is NatHERS Existing Homes?
Because a home energy rating measures the dwelling and its systems, the assessment is easier when useful information is available.
Helpful information may include:
For a practical preparation checklist, see What Information Do You Need for a Home Energy Rating?
A home energy rating measures how a dwelling performs for energy efficiency, comfort and likely energy use. For existing homes, it may consider the building fabric, insulation, windows, shading, heating and cooling, hot water, appliances, solar, batteries and upgrade potential.
Yes. Insulation is one of the key elements that can influence a home energy rating. The assessment may consider ceiling, roof, wall and floor insulation where this information is available, observable or able to be assessed under the relevant pathway.
Yes. A home energy rating may consider heating and cooling needs, installed systems and how the dwelling manages heat gain and heat loss. This helps explain comfort and likely energy demand.
Depending on the rating pathway, solar PV and batteries may be considered as part of whole-of-home energy performance. These systems can influence how much energy the home uses from the grid.
A home energy rating is not the same as an energy bill review. Bills are affected by tariffs, occupancy and behaviour. The rating focuses more directly on the dwelling, its systems and its likely performance.
Yes. A home energy rating can help identify possible upgrade opportunities, such as insulation improvements, glazing changes, draught sealing, more efficient systems, solar, batteries or staged renovation measures.
Assessment Preparation
Prepare available property details so the assessment pathway can be reviewed.