# Energy
Up to 40 per cent of the world's energy resources are used in buildings. Good building design can decrease power consumption, save money, reduce the impact of climate change and provide comfortable conditions for building occupants.
In the energy category, BESS awards points for passive design, energy efficient services / appliances and energy fuel choices that deliver greenhouse and energy savings above a benchmark building. The benchmark building is based on minimum standards in the National Construction Code (NCC) of Australia including the whole-of-home reference case, the Minimum Energy Performance Standards (MEPS), market availability and other standards.
Applicants have some flexibility for achieving points, through pursuing improvements to the building shell (passive design), increasing the efficiency of mechanical and electrical system components and also by designing all-electric developments. Onsite renewable energy generation can assist in reaching higher performance standards, or offset energy consumption of buildings with average performing building shell or appliances.
Our Operational Energy Fact Sheet (opens new window) can help you with design strategies for your development.
# Energy Profile Questions1
BESS requires you to complete the Energy profile questions. These questions are applicable to the whole site.
Are you installing a solar photovoltaic system?
If you select ‘Yes’, BESS will activate the Solar PV calculator. You can then enter the details of one or more Solar PV systems.
Are you installing any other renewable energy system(s)?
Select Yes here if you are installing another type of renewable energy system, such as micro-wind. There is no in-built calculator for these systems - you will need to supply your own calculations and enter results directly into Energy credit 4.4. This question does not refer to solar hot water – solar hot water is defined in a separate question.
Energy supply
This question is asking what energy supplies are connected to the building. With options for all electric, electricity and natural gas or electricity and LPG gas. Your selection here will affect the questions and credits that are applicable to your project.
Are you installing a co-generation or tri-generation system?
This refers to a combined heat and power system or a combined heat, power and cooling system. This energy profile question is only asked for non-residential and mixed use developments.
# Solar PV Calculator
The Solar PV calculator is activated when the user answers Yes to this in the Energy Profile. To complete the Solar PV calculator BESS users will need:
- The size of the proposed solar system in kilowatt peak (the lesser of the panel capacity or the inverter size)
- The orientation of the panels - ideally north, possibly west to match the evening peak (or a combination of the two)
- The inclination of the panels - this is the angle from horizontal
For a mixed-use building, BESS needs to know the building class the solar system is being used for.
If there are arrays oriented in different directions, or if it is a townhouse development and each townhouse has a separate solar array, enter each array separately.
# Approaches to completing the Energy Section
# Non-Residential
For non-residential developments, you can opt to use the Deemed to Satisfy (DtS) method or provide your own calculations (via energy modelling) to achieve Energy credits 1.1, 2.1, 2.2, 2.7 and 3.2.
When selecting DtS - this applies to all non-residential spaces. Under the DtS method there is no partial compliance.
# Deemed to Satisfy
Under the DtS method, if you answer “Yes” to ALL the following questions, then points are awarded for the energy credits shown above.
- Do all exposed floors and ceilings (forming part of the envelope) demonstrate a minimum 10% improvement in required NCC2022 insulation levels (total R-value upwards and downwards)?
- Does all wall-glazing construction demonstrate meeting the minimum NCC2022 requirements through a facade calculator?
- Are heating and cooling systems within one Star of the most efficient equivalent capacity unit available, or Coefficient of Performance (CoP) & Energy Efficiency Ratios (EER) not less than 85% of the CoP & EER of the most efficient equivalent capacity unit available?
- Are water heating systems within one star of the best available, or 85% or better than the most efficient equivalent capacity unit?
# Provide own calculations - Non-Residential Energy Modelling
Where you select 'provide own calculations', preliminary modelling is required to demonstrate that energy credits have been achieved. Preliminary modelling must meet all the requirements, methodology and assumptions using Verification Method JV3 of the National Construction Code Volume 1. Refer to the most recent version of the NCC Volume 1 Energy Efficiency Handbook for more detail.
For the purposes of the BESS assessment, the following are required.
Modelling for inputs to BESS include 3 runs (aligned with NCC 2022 requirements):
- Reference fabric and reference services
- Proposed fabric and reference services
- Proposed fabric and proposed services
Proposed and reference have the same meaning as in the NCC.
The modelling for BESS inputs must be completed as follows:
- Reference case heating, cooling and hot water systems are to be the same fuel type as the proposed.
- Must include hot water systems (with reference system set as electric storage meeting MEPS or 4 star gas storage hot water meeting MEPS)
- Lighting results are to be input separately to heating and cooling
- Must exclude renewable energy generation
- Must exclude vertical transport
The modelling results are used for calculations in the following BESS energy credits:
Energy 1.1 Thermal Design Non-Residential – reduction is proposed fabric with reference services compared to reference fabric with reference services
Energy 2.1 Greenhouse Gas Emissions – reduction is proposed fabric with proposed services and proposed hot water compared to reference fabric with reference services and hot water reference
Energy 2.2 Peak Demand – reduction is peak thermal cooling load proposed fabric with proposed services compared to peak thermal cooling load reference fabric with reference services
Energy 2.3 Electricity Consumption – reduction is proposed fabric with proposed services and proposed hot water compared to reference fabric with reference services and hot water reference
Energy 2.4 Gas Consumption (if applicable) – reduction proposed fabric with proposed services and proposed hot water compared to reference fabric with reference services and hot water reference
Energy 3.2 Hot Water – reduction is hot water proposed compared to hot water reference
Energy 4.2 Renewable Energy Systems - Solar – building class energy consumption is aggregate of proposed fabric with proposed services, proposed hot water and proposed lighting
# Note: BESS and NABERS
The modelling approach in NABERS tests the outcomes against a threshold, rather than against a base case / reference case. Therefore, the BESS inputs do not align with the NABERS approach. Councils may accept a NABERS energy commitment as acceptable demonstration of energy performance.
# Commercial Building Disclosure Program
The Australian Government Department of the Environment and Energy manages the Commercial Building Disclosure (CBD) Program, which applies to most office space with a net lettable area of 1000 square metres or more. The program requires credible energy efficiency and greenhouse emissions data to be provided to prospective buyers and tenants.
The program does not apply to new buildings where a certificate of occupancy (or equivalent) has either not yet been issued or was issued less than two years earlier. However, the CBD program will apply when most office space of 1000 square metres or more is being:
- sold
- leased
- subleased
To determine if your project will be affected by the CBD program, refer to http://cbd.gov.au/
Achieving a high energy reduction in BESS will provide regulatory and commercial benefits including when mandatory disclosure is required for an office building.
# Residential
You have the choice of using the in-built energy calculator or providing your own calculations.
# Provide own calculations
If you provide your own calculations there are fewer inputs in the BESS tool, but you must provide evidence to demonstrate that you are meeting Councils’ objectives for energy.
# Built-in Calculator
If using the built-in calculator, complete the 'Dwelling Profile' section by entering information about the NatHERS rating and various appliance types. The information you enter here is used to calculate energy consumption and greenhouse emissions against a benchmark building, and the results feed into Energy credits 1.2, 2.1, 2.7, 3.4, 4.2 and 4.5.
# Dwelling Energy Profiles
The table lists the grouped dwellings as they were initially entered in the project details stage.
Any sample of dwellings should be representative and allow a weighted average result to be calculated. BESS allows this to be set up on the Project Details Page by entering each sample along with the number of dwellings in that thermally similar group. Alternatively, a weighted average can be taken for groups of dwellings that share the same exposure characteristics.
When entering information in this table the ‘Select all’ button is the top left-hand corner of the table to copy a selection across all columns.
This table links back to the ‘Dwellings’ table on the BESS ‘Project Details’ page. When entering details on the Project Details page, you can group dwellings with similar thermal properties and similar systems. These groupings will automatically appear on the energy page in the ‘Dwelling Energy Profiles’ table. Creating groups of dwellings in the project details page helps streamline the BESS calculation engine process time.
# A note about dwelling area
When entering information on the Project Details pages, the input for dwelling area is the total dwelling area (excluding garages), NOT just the conditioned area or usable area.
# Completing the ‘Dwellings Energy Profiles’ table:
# Identify the spaces above and below the dwelling, and the number of exposed sides
‘Exposed sides’ refers to the walls (not the floor or ceiling). A dwelling is considered to have an exposed side if more than 2/3 of the side is not connected to an adjoining conditioned space.
# Input the annual heating and cooling energy loads.
These can be found on the NatHERS certificate. The heating and cooling load is how much energy is needed per square meter to heat or cool the dwelling. BESS also asks for the NatHers star rating for that dwelling or group of dwellings.
BESS takes the heating and cooling loads and considers them in context of what is above or below the dwelling – either conditioned spaces or non-conditioned spaces. Based on this information BESS makes an assumption about the heating and cooling needs of the dwelling. That is – how much energy will be required to keep the building comfortable in both summer and winter.
# Input the heating and cooling system types and their efficiencies.
BESS will then calculate predicted energy requirements. If you aren’t putting in a cooling system and have a low cooling load, your project will be rewarded. However, if you select no air-conditioning and you have a high cooling load, BESS will assume a low efficiency air conditioner is installed at a later date.
# Input the hot water system type.
Solar is not included in this list. If the hot water has a solar component, first select the booster system – where it asks for the type of hot water system, and then on the next row, include the contribution that solar will make to the hot water heating. This contribution is shown as a percentage.
There are multiple options for heat pump hot water systems. As there are currently no star ratings for hot water heat pumps, the four options provided in BESS are 'Band 1, Band 2, Band 3 and Band 4'.
The efficiency of each 'band' is determined from the number of Small Scale Technology Certificates (STCs) available. This information is updated each calendar year.
Look up the number of STCs for a specific model on the Clean Energy Regulator website (opens new window), and check this against the numbers published below. You can do this when completing the BESS report or at a later date.
The range of heat pump models that fit within each efficiency 'band' in BESS will stay consistent, even though the number of STCs reduces each year (in line with the STC calculation regulated by the Clean Energy Regulator).
# Heat Pump Hot Water - Efficiency bands by STCs applicable (2024)
| Band | STCs applicable |
|---|---|
| Band 1 | 21 STCs or less |
| Band 2 | 22 STCs |
| Band 3 | 23 STCs |
| Band 4 | 24 STCs or more |
# Heat Pump Hot Water - Efficiency Bands by STCs applicable (2025)
| Band | STCs applicable |
|---|---|
| Band 1 | 18 STCs or less |
| Band 2 | 19 STCs |
| Band 3 | 20 STCs |
| Band 4 | 21 STCs or more |
# Input information about the clothes drying options.
The inputs in this table are determine the energy use and the projected greenhouse gas emissions from the project.
The exception is the NatHERS star rating. This is used in the Energy 1.2 credit.
The total number of dwellings entered in BESS must always equal the number of dwellings in the development.
# Residential Energy Modelling - NatHERS ratings
The Nationwide House Energy Rating Scheme (NatHERS) is a star rating system (out of ten) that rates the energy efficiency of a home, based on its design. NatHERS uses software based on scientific research by the CSIRO, which estimates the amount of energy needed for heating and cooling.
A NatHERS rating considers many factors including local climate, building size, orientation, shading, and construction – including walls, floors, windows, doors, roofs and ceilings.
For residential projects, a preliminary NatHERS rating is expected for all [[thermally similar dwellings](/tool-notes/bess9/glossary.html#thermally-similar-dwellings)](/tool-notes/bess9/glossary.html#thermally-similar-dwellings) wherever a claim is made that the dwelling will exceed the minimum requirements under the National Construction Code. For the purposes of sampling, dwellings can be grouped where they share similar thermal properties.
Any sample of dwellings should be representative and allow a weighted average result to be calculated. BESS allows this to be set up on the Project Details Page by entering each sample along with the number of dwellings in that thermally similar group. Alternatively, a weighted average can be taken for groups of dwellings that share the same exposure characteristics.
For developments that include dwellings intending to meet minimum NatHERS requirements only, and have not undertaken preliminary NatHERS, the user must enter default minimum 7 Star NatHERS heating and cooling loads for the relevant climate zone.
# Using default NatHERS values
For Class 1 dwellings use an 80% heating 20% cooling split of the total MJ/m2/year figures in the table below. For Class 2 apartments use a 60% heating 40% cooling load split of these values:
# NatHERS heating and cooling limits to meet a 7 star standard in Victorian climate zones
| Climate Zone | 7 star heating and cooling total (MJ/m2/year) |
|---|---|
| Melbourne 21 | 62 |
| East Sale 22 | 100 |
| Mildura 27 | 79 |
| Tullamarine 60 | 99 |
| Moorabbin 62 | 85 |
| Warrnambool 63 | 112 |
| Cape Otway 64 | 88 |
| Ballarat 66 | 161 |
| Thredbo 69 | 277 |
Source: 2022 NatHERS Starbands
For apartments, Planning Scheme Clauses 55.07 and 58.07 include maximum cooling loads. NatHERS ratings are required to show the council these would be met.