Home Energy Rating Certificate

Homes are given a star rating between 0 and 10. This is based on the home’s heating and cooling needs, considering its local climate, design, materials and construction. Assessors use Nationwide House Energy Rating Scheme (NatHERS) computer modelling tools to predict the amount of heating and cooling your home will need to stay comfortable year-round. This is called thermal performance. 

It includes the:

• orientation and layout of the home
• roof, wall and floor materials, including insulation and construction methods
• window size, orientation and the performance of glazing and window frames
• design of shading elements and how well they protect the home in summer months and maximise solar gains in cooler months  
• impacts of ventilation strategies and draughts.  

Below is a general guide to star ratings:

• a 0-star rated home is quite uncomfortable – too hot in summer and too cold in winter. It will require a lot of energy to heat and cool.
• a 7-star rated home will need a small amount of heating and cooling to keep it comfortable to live in. This is the minimum standard for new houses under the National Construction Code 2022.
• a 10-star home is very energy efficient. It will remain comfortable year-round, with limited, or no heating or cooling.

Homes are given a Home Energy Rating on a scale of 0 to 100.

This rating builds on the star rating by applying additional information to calculate the energy use of your whole home including appliances.  It considers the home’s thermal performance, energy used for heating and cooling, hot water and other major appliances, as well as the impact of energy generated by solar panels, building a useful snapshot of your home's energy use and greenhouse gas emissions. 

Appliances assessed as part of your home energy rating include: 

• heating and cooling appliances
• hot water systems
• cooking appliances
• lighting
• pool/spa pumps
• on-site energy generation from rooftop solar and battery storage
• plug in appliances. 

Homes with higher home energy ratings cost less to run. They often have more energy efficient designs and appliances and may also generate their own electricity. The current minimum home energy rating for new homes is 60 for houses (class 1) and 50 for apartments (class 2).  

While the home energy rating scale ranges from 0 to 100 (where 100 is a net zero energy value home), ratings above 100 are possible. One way that a home may rate over 100 is where it generates and exports more energy than it uses.

This chart shows the percentage of time each year that your home is likely to be comfortable or when heating or cooling is likely required to maintain comfort. A well-performing home will feel ‘comfortable’ most of the time. 

The comfort chart uses predefined set temperatures to indicate how often heating or cooling might be required. Your actual use of heating and cooling will depend on your individual preferences. 

You can use the comfort indicator to:

• understand your star rating and compare performance across homes
• identify and prioritise upgrades to reduce heating or cooling energy use.

Thermal comfort depends on both environmental (e.g. temperature, humidity, and airflow) and personal (e.g. activity and clothing) factors. The CSIRO is researching thermal comfort in homes to support the development of a new Comfort Rating. This work may inform future updates to the certificate.

This section provides information on what powers your home. It details where your energy is coming from and provides information on any rooftop solar and battery storage systems. 

If your home has solar, this section shows the predicted generation of the system, and an estimation of the energy consumed on site and exported to the grid. A home energy rating without solar is also provided to help households better compare ratings between homes with and without solar. 

Emissions information is also included. The emissions factors used on the certificate come from the National Greenhouse Accounts Factors. Revised factors are published each year, and the certificate will be updated regularly to ensure emissions information is accurate at the time the certificate is generated. The National Greenhouse Accounts Factors version used is stated on the certificate. 

This section provides the key building details contributing to a home’s star rating. This helps you understand the link between building details, star rating and comfort. It includes key information on construction, material efficiencies (e.g. insulation R values and window U values) and how that data has been collected. 

Ceiling and roof, external walls, and floors 

This section details the construction of your home. The R value of added insulation is provided alongside the materials used. Higher R values mean better performance. Default insulation values based on the year of construction may be used and are indicated on the certificate. These values are used when assessors cannot inspect, or access evidence of installed insulation. If you have made upgrades to your home, such as retrofitting insulation, evidence must be provided for this to be reflected in your rating.

Only two main constructions (based on area/location) are listed for each category. 

Visit Your Home for more information on insulation. 

Windows and window coverings  

This section details the frame type and glazing used in your windows. Information on the type and presence of window coverings such as curtains and external awnings are also included as these have an impact on comfort and your home’s ratings. 

Visit Your Home for more information on windows. 

Air tightness  

This section details the air tightness of your home. Unless you have conducted a blower door test to measure this value, the number provided is the assumed air tightness. This is based on the presence of weather seals on windows/doors and building elements that contribute to draughts (e.g. unsealed downlights/exhaust fans, gaps, cracks, and wall vents).  

If you have a well-sealed home and are wanting to see this reflected in your rating or are looking to identify and fix gaps in a draughty home, you could consider a blower door test. 

Visit Your Home for more information on ventilation and airtightness.

Energy loads

Energy loads are used to determine your home’s star rating. Both the annual and split heating and cooling loads are provided in megajoules per metre squared per annum. This information is included to help compare ratings between homes, both new and existing. 

This section provides details on appliance type and efficiency, energy use and fuel source. The predicted annual energy consumption is provided by end use area (i.e. the total for heating, cooling, etc). Charts are included to help you understand where you are using energy, with the largest use appearing first. Households may wish to upgrade their highest use area appliances first to maximise savings.

The ratings use assumptions for appliance energy use, including expected time of use and set temperatures. These assumptions ensure ratings can be compared between homes. Your actual energy use will vary, depending on appliance use and how many people live in your home. 

Heating

The type and performance of your three main heating appliances are shown on the certificate. If no heating appliances are installed in rooms that are assumed to receive heating, a default appliance category may also be shown. Default appliances are included to ensure consistency of ratings between homes.

The efficiency of all heating appliances is shown as a Coefficient of Performance (COP) or Heating Seasonal Performance Factor (HSPF), which are measures of appliance efficiency. The higher the number the more efficient the appliance is. The use of COP and EER on home energy rating certificates enables comparison of appliance efficiency across different appliance and fuel types. If a heating appliance has a Greenhouse and Energy Minimum Standards (GEMS) rating label, this information is also shown. As the GEMS star rating scale has been adjusted over time in response to improvements in appliance efficiency, the star rating of an older appliance may not be equivalent to a newer one. By referring to the reported COP or HSPF users can compare efficiency values. For more information on appliance energy efficiency and rating labels, visit Energy Ratings. 

A note on defaults:
For existing homes, the default heating appliance is a plug-in electric heater. This default recognises that in an existing home with no permanently installed heating device, a plug-in electric heater is the go-to appliance to maintain comfort.

Cooling

The type and performance of your two main cooling appliances are shown on the certificate. The efficiency of cooling appliances is shown as an Energy Efficiency Ratio (EER) or Total Cooling Seasonal Performance Factor (TCSPF), which are measures of appliance efficiency. The higher the number the more efficient the appliance is. If a cooling appliance has a Greenhouse and Energy Minimum Standards (GEMS) rating label, this information is also shown. For more information on appliance energy efficiency and rating labels, visit Energy Ratings. As the GEMS star rating scale has been adjusted over time in response to improvements in appliance efficiency, the star rating of an older appliance may not be equivalent to a newer one. By referring to the reported EER or TSPF users can compare efficiency values.

The presence of ceiling fans is listed under cooling. However, they are not factored into your home energy rating. Ceiling fans can provide cooling in milder conditions before switching air conditioners on and should be used alongside air conditioners on hot days to reduce overall energy use. The size and location of ceiling fans can improve ventilation and are factored into your home’s star rating. 

Hot Water 

The type, fuel source and efficiency of hot water systems are listed alongside the annual energy consumption. 

Cooking appliances 

The type and fuel source of your cooktop and oven are shown on the certificate. 

Lighting 

The lighting power density and annual lighting energy use are shown alongside the number of unsealed or halogen downlights. 

Pool and spa pumps 

The type and efficiency of pool and spa pumps are shown on the certificate. Home energy ratings do not factor in any energy used by pool and spa heaters. If you have a pool, savings can be made through electrification of heaters, pump replacement and the use of quality covers. If you have solar, you should investigate the use of timers to maximise self-consumption of energy generated on site.

Plug in appliances 

This is an inbuilt assumption to account for the energy used by plug in appliances such as fridges, televisions and washing machines. An assumption is used to ensure consistency between ratings. Actual plug-in appliance energy use will vary in your home due to the number and type of appliances you have as well as the way you use them.

The Home Energy Rating certificate may be used to disclose the energy performance of existing homes and to access upgrade finance and state and territory upgrade and incentive schemes. Existing Home Energy Ratings cannot be used to demonstrate regulatory compliance with the National Construction Code. NatHERS ratings use computer modelling to evaluate a home’s energy efficiency and performance. They use localised climate data and standard assumptions on how people use their home to predict the heating and cooling energy loads and energy value of the whole home. The thermal performance star rating uses the home’s physical conditions such as layout, orientation and fabric (i.e. walls, windows, floors, roofs and ceilings) to predict the heating and cooling energy loads. The Home Energy Rating uses information about the home’s appliances and onsite energy generation and storage to estimate the homes energy value. The actual energy loads, cost and greenhouse gas emissions of a home may vary from that predicted. This is because the assumptions will not always match actual occupant usage patterns. For example, the number of occupants and how people use their appliances will vary. Energy efficient homes use less energy, are warmer on cool days, cooler on hot days and cost less to run. 

NatHERS existing Home Energy Rating certificates can only be generated by an accredited existing homes assessor. Valid certificates contain a QR code linking to a digital version of the certificate. From launch, existing homes assessors will be accredited by the NatHERS Administrator. Assessor accreditation includes strict quality assurance processes, and professional development requirements ensuring consistently high standards for assessments. Any queries about your certificate should be directed to the listed assessor. If the assessor is unable to address questions or concerns, contact the NatHERS Administrator at admin@nathers.gov.au

For more information on assessor accreditation visit the assessor toolkit.  

The NatHERS existing Home Energy Rating Certificate format is developed by the NatHERS Administrator. However, the content in the certificate is entered by the assessor. It is the assessor’s responsibility to use NatHERS accredited software correctly and follow the NatHERS for existing homes Technical Note to produce a Home Energy Rating Certificate. The predicted annual energy load, cost and greenhouse gas emissions on the certificate are an estimate based on an assessment of the dwelling by the assessor. It is not a prediction of actual energy use, cost or emissions. The information and ratings may be used to compare how other dwellings are likely to perform when used in a similar way. Information presented in this report relies on a range of standard assumptions (both embedded in NatHERS accredited software and made by the assessor who prepared this report), including assumptions about occupancy, behaviour, appliance performance, indoor air temperature and local climate. Due to the nature of assessing existing homes, pre-determined default assumptions based on the year of construction may be used when specifying building details such as insulation. Not all assumptions made by the assessor using the NatHERS accredited software tool are presented in this report, and further details may be obtained from the assessor.