Home Energy Rating
A home energy rating for existing homes gives homeowners, buyers, property professionals and project teams a clearer understanding of how an established dwelling performs.
Unlike a new-build energy assessment, which is usually completed from architectural plans before construction, an existing home rating looks at the dwelling as it currently stands. It considers the building fabric, thermal comfort, energy use, installed systems and practical opportunities for improvement.
As Australia moves toward clearer energy performance information for established dwellings, home energy ratings are becoming more important for renovation planning, electrification, household running costs and long-term property value.
Quick Answer
A home energy rating for existing homes is an assessment of how an established dwelling performs in terms of energy efficiency, comfort and likely running costs. It helps identify how the home manages heat, cold, ventilation, appliances and energy demand.
For existing Australian homes, a rating can support better decisions around insulation, windows, draught sealing, heating and cooling, hot water, solar, electrification and renovation planning. It gives the homeowner a more structured way to understand what should be improved first.
Home energy ratings for existing homes are different from BASIX or standard new-home NatHERS assessments. BASIX is mainly a NSW planning pathway for new residential development and major alterations. Existing home ratings are focused on the current condition and upgrade potential of homes that have already been built.
Certified Energy can assist homeowners and project teams in understanding which home energy rating pathway may apply, including NatHERS-aligned existing home pathways and related residential energy efficiency assessment options.
A home energy rating for an existing dwelling looks at the way a home performs as a built environment, not only as a collection of appliances.
Depending on the assessment pathway, it may consider:
The purpose is not simply to produce a number. The value of the rating is that it helps translate building performance into practical decisions. A homeowner may discover, for example, that upgrading ceiling insulation should come before replacing an air conditioner, or that draught sealing may improve comfort before larger renovation works begin.
New homes are usually assessed before they are built. The consultant works from drawings, specifications and construction details to model the proposed dwelling against the relevant energy performance pathway.
Existing homes are different because the building is already there. The assessment must respond to the real dwelling: its age, construction quality, previous renovations, system choices and defects. Many Australian homes were built before modern energy efficiency expectations were introduced, which means they can be uncomfortable, costly to run and difficult to improve without clear advice.
This is why existing home ratings need to be practical. They should help homeowners understand the current condition of the house and the most useful sequence of improvements.
A home energy rating can help a homeowner make better decisions before spending money on upgrades.
Without an assessment, energy upgrades can become fragmented. A household may install solar panels, replace appliances, add blinds or upgrade heating, but still live in a home that loses heat in winter or gains too much heat in summer.
A rating helps identify where the underlying performance issues sit. For some homes, the priority may be insulation and draught sealing. For others, it may be inefficient heating and cooling, poor hot water performance, or window exposure. In a renovation context, the rating can also help determine which upgrades should be integrated before walls, ceilings or floors are closed up.
A home energy rating may be useful when:
It may also become more relevant as the property market, government programs and household energy disclosure systems continue to develop. For many homeowners, the rating will be less about immediate compliance and more about clarity: understanding what the home is doing, why it feels uncomfortable, and where money should be spent first.
NatHERS has traditionally been associated with new homes and major renovations. It provides star ratings that describe the thermal performance of a home, usually using approved software and detailed modelling inputs.
NatHERS is now being expanded to support ratings for existing homes. This creates a more consistent national language around housing energy performance, allowing existing dwellings to be assessed in a way that better aligns with the rating systems already used for new homes.
For homeowners, the important point is that a NatHERS-aligned existing home rating is not simply a new-home assessment copied onto an old house. Existing homes require a different practical approach because the dwelling has already been built and may contain unknowns, ageing materials, past alterations and real-world performance issues.
The Residential Efficiency Scorecard is a government-supported home energy rating and advice program that rates a home’s energy use and comfort and provides tailored upgrade recommendations.
It has helped establish a more practical way for Australian households to understand existing home performance. As the national Home Energy Rating system develops, Scorecard and NatHERS-aligned existing home pathways sit in the same broader movement: giving households clearer, more usable information about the homes they already live in.
No. BASIX is a NSW sustainability pathway used mainly for new residential development and certain alterations and additions. It is connected to planning and approval requirements.
A home energy rating for an existing home is different. It is focused on understanding the current performance of an already-built dwelling and identifying improvement opportunities. It may support renovation planning, household comfort, energy efficiency and upgrade sequencing, but it is not the same as preparing BASIX documentation for a new-build approval pathway.
That distinction matters for homeowners. A person searching for an existing home rating may not need BASIX at all. They may need an assessment that explains the condition and performance of their current home.
The required information depends on the assessment pathway, but homeowners may be asked to provide or assist with:
In many existing homes, not all details are known. That is normal. A good assessment process should work with the information available and identify where assumptions, observations or further checks are needed.
One common misunderstanding is that a rating is only about energy bills. Bills are part of the picture, but they are affected by household behaviour, tariffs, appliances, occupancy and climate. A rating is more useful when it helps explain the performance of the home itself.
Another misunderstanding is that solar panels automatically solve poor energy performance. Solar can be valuable, but it does not necessarily make a home comfortable. A poorly insulated, draughty or overheated home may still need building fabric improvements.
A third misunderstanding is that every upgrade should be done at once. In many homes, staged improvements are more realistic. The benefit of a rating is that it can help prioritise the sequence.
For homeowners, a home energy rating can support a more confident upgrade plan.
For architects and designers, it can provide useful context before renovation design begins. Understanding the existing dwelling’s performance can help shape decisions around glazing, insulation, shading, airtightness and services.
For builders, it can clarify which performance upgrades need to be integrated into the works rather than added later. For property professionals, it can help explain comfort and operating-cost considerations that are often invisible during a standard inspection.
For consultants, it creates a bridge between technical building performance and practical household advice.
Existing Home Energy Advice
If your project involves an existing home, renovation or staged upgrade plan, Certified Energy can assist with understanding the most suitable Home Energy Rating pathway.
Speak with Certified Energy about Home Energy Rating pathways