NatHERS vs NABERS for Apartment Buildings

What is the difference between these two different rating systems for the built environment, in the context of residential apartment buildings....

In the context of apartment buildings, NatHERS (Nationwide House Energy Rating Scheme) evaluates the thermal performance and energy use of individual dwellings, whereas NABERS (National Australian Built Environment Rating System) for Apartment Buildings focuses on the common areas and shared services of the building.

Feature	NatHERS	NABERS
Primary Focus	The individual apartment unit's "shell" (thermal comfort) and major appliances.	Shared services and common areas (lifts, lobbies, car parks, pools, gyms).
Measurment	Theoretical modelling of energy needed to heat/cool based on design and materials.	Actual operational performance based on 12 months of historical utility data.
Rating Scale	0 to 10 stars for thermal;  The rating measures the thermal performance (heating/cooling needs) based on design, materials, and climate, not the appliances themselves.  A separate "Whole of Home" rating (out of 100) now measures energy use from appliances, lighting, and solar panels.	1 to 6 stars for energy and water performance.
Mandatory or Voluntary	A NSW pilot program that started in September 2025 will form the base of a national rollout of mandatory NatHERS rating for every established property advertised for sale or rent	Voluntary, used by owners corporations to track and improve operational efficiency. Mainly done by high rise apartment buildings in the City of Sydney and City of Melbourne. After being launched in 2018, maybe 2,000 apartment buildings have been rated out of 360,000 apartment buildings nationwide. Isn't an appropriate rating system for "red brick" or "white brick" walkups which are still the most common form of apartment building in NSW.
Validity	Permanent for that specific design unless major alterations occur.	Valid for 12 months; requires annual reassessment to remain current.

1) Deeper Dive on NatHERS Rating (Thermal rating out of 10 stars)
Since introduction in 2022, most new homes have to have a minimum 7 star rating. 10 stars is extremely efficient.
A 7 Star rated home can still need 32MJ per square metre as a cooling load.  A 7.8 Star rated home may only need 16MJ per square metre as a cooling load (from air conditioning) as the scale isn't linear. An 8-star home uses half as much energy as a 6 star home.

Lack of shading over eastern or western windows/doors can be a culprit in terms of thermal performance of apartments. Factors such as orientation, glazing and shading, insulation levels, and access to cross-ventilation – all  fundamentally shape comfort and energy use. 

With seven out of 10 established homes having an estimated rating below 3 stars there is large potential for improvement.  

In the ACT which has had mandatory disclosure for over 20 years, ACT scheme found that the price premium for a 6-star house over a 3-star one was 2.4 per cent and that for a 7-star house it was 9.4 per cent.
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2) Deeper Dive on NatHERS Whole of Home Rating (out of 100 points)
A NatHERS Whole of Home rating assesses the energy performance of a dwelling’s fixed appliances and onsite energy generation, resulting in a score out of 100 (or up to 150). It complements the thermal star rating by measuring energy used for heating, cooling, hot water, lighting, pool/spa pumps, and cooking, alongside solar and battery storage. 

Key components involved in a Whole of Home assessment include:

• Appliance Efficiency: Evaluation of heating, cooling, and hot water systems for energy efficiency.
• Lighting & Power: Analysis of fixed lighting and other fixed electrical appliances.
• Onsite Generation: Calculation of solar PV generation and battery storage capability. In the apartment context use of Allume Energy Solshare for shared solar and batteries or individual solar systems for townhouses would contribute towards this.
• Energy Budget: Used to demonstrate compliance with the National Construction Code (NCC) for new homes, aiming to reduce energy costs.
• Rating Scope: The assessment measures the energy value of the home, helping to identify opportunities to reduce energy consumption.
• Software & Assessment: Accredited assessors use specialized software to calculate the rating, which is often combined with a 7-star thermal rating.

3) Deeper Dive on NABERS for Apartment Buildings Ratings

NABERS for Apartment Buildings rating measures the actual operational performance of a building’s common property. It tracks how much energy and water are consumed by the services shared by all residents. 

Core Coverage Areas
The rating typically covers utilities paid for by the owners corporation: 

• Energy: Measures consumption from shared facilities including lifts, lobby lighting, car park ventilation, gyms, and pools.
• Water: Can include shared water use only (e.g., gardens and pools) or all water use in the building, depending on the available metering and owner preference.

Key Features

• Performance Scale: Buildings are rated from 1 to 6 stars, where 3 stars is the market average and 6 stars represents a market-leading, highly efficient building.
• Operational Focus: Unlike design-based ratings, this requires 12 months of historical data (utility bills) to reflect real-world usage.
• Validity: Ratings are valid for 12 months to ensure they reflect current management practices and equipment performance.
• Exclusions: It specifically excludes the energy and water used inside individual apartments. Currently, gas-powered central hot water systems are also often excluded due to data availability issues. 
  
  

Eligibility Requirements
To qualify for a NABERS rating, an apartment building must have:

• At least four apartments.
• At least two floors. e.g. vertically stacked apartments
• A registered strata plan.

​There is a renewable energy indicator which shows how much energy is generated from renewable resources.
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The fact that a NABERS for Apartment Buildings rating has been completed, is often used as a leading indicator of the strata building being a proactive and front-leaning strata scheme which has overcome major remediation issues and is looking towards futureproofing the apartment building.