There are two rating systems for retrofitted buildings:
the National Australian Built Environment Rating System and
Green Star ratings.
NABERS ratings
The National Australian Built Environment Rating Scheme (NABERS) is a suite of tools used to rate the environmental performance of buildings. NABERS Energy was formerly known as the Australian Building Greenhouse Rating (ABGR) scheme.
There are four tools in the NABERS suite for office buildings:
- Energy
- Water
- Waste
- Indoor environment
Each tool gives buildings a rating out of five stars. Ratings are based on building performance data, not design documents and simulations.
There are three types of rating: base building, tenancy and whole building. A base building rating considers the building’s central services. For an energy rating this usually includes air conditioning, lifts and common area lighting.
A tenancy rating considers the environmental impact of an individual tenancy. For an energy rating this usually includes the occupant’s light and power consumption.
A whole building rating considers both base building and tenancy data.
Energy and water tools are available for hotels and shopping centres.
For a new office building, retrofit or tenancy fit-out, a NABERS Commitment Agreement can be used to achieve future performance targets.
Why is it important to get a baseline NABERS Energy audit?
Baseline audits are necessary to benchmark how a building is performing and to measure any reductions in energy, water and waste consumption. NABERS provides a robust mechanism that allows a building to be compared annually to its peers on a like to like basis. A rating is valid for one year, and should be updated annually to manage performance and track improvements.
How does a building owner go about obtaining a rating?
There are two types of NABERS ratings – self-assessed and accredited.
Building owners can self-assess by visiting NABERS, selecting the appropriate rating calculator and entering their building’s data. A self-assessed rating will give an indication of how well the building is performing. A self-assessment cannot be promoted or reported.
To promote a building on the basis of its NABERS rating and use the NABERS logos, an accredited rating is needed. These are performed by accredited assessors.
Visit NABERS for a list of accredited assessors. The accredited assessor will look at the building and its performance over the past 12 months then calculate a rating.
How much does it cost?
Self-assessment calculators can be accessed for free. The cost of an accredited rating varies depending on the type of rating being sought, the size of the building and the availability of the relevant data.
How do building owners obtain billing data and what do they do with it?
Billing data can be obtained from the building’s energy providers.The building’s facility manager should also be able to provide relevant data for the assessment process.
Other data that will be required for the assessment process includes the building’s floor area, the number of hours per week the building is occupied and the number of computers in the building. These figures can be found in the original design documents or through the building’s facility manager.
This data can be entered into the self-assessment calculators discussed above or supplied to an accredited assessor so they can carry out a full rating.
Green Star ratings
Green Star is a suite of building rating tools administered by the Green Building Council of Australia to evaluate the design of buildings.
There are six tools available:
- Office design
- Office as built
- Office interiors
- Health care
- Retail centre
- Education
Tools for industrial, multi-unit residential, mixed use and existing office buildings are at the pilot stage at the time of writing.
Each tool gives a building a rating out of six stars. A four star rating signifies best practice. Five stars signifies Australian excellence and six stars indicates world leadership.
Green Star uses broader environmental criteria than NABERS. It rates buildings in the following areas: management, indoor environment quality, energy, transport, water, materials, land use and ecology, emissions and innovation.
The other major difference between the two schemes is that Green Star rates building designs, not building performance.
Green Star ratings are just as relevant to retrofit projects as they are to new buildings. The scope of the retrofit works will dictate which tool is the appropriate one to use.
Visit the Green Building Council of Australia for more information about Green Star ratings.
How does a building owner go about obtaining a rating?
The Green Star rating tools can be downloaded free from the Green Building Council of Australia and building owners can enter their building data to get an indicative rating.
A rating cannot be publicly claimed or promoted until it is certified. Certified projects are also allowed to use the Green Star logo in their promotion.
Projects need to be registered with the Green Building Council of Australia and the project team needs to provide documentary evidence to support the rating submission. A detailed outline of the certification process is available here.
How much does it cost?
The cost of a certified Green Star rating varies depending on the size of the project and the availability of the relevant design data.