WHAT energy efficiency REPORT DO I need for my Commercial project?

The National Construction Code (NCC) helpfully provides a range of Energy Efficiency assessment methods, recognising that different projects have different features that may be suited to one method or another. Each assessment method produces a different kind of report. It’s important to note they are all valid under the legislation; any one of them can be used to demonstrate Section J Energy Efficiency compliance.

The decision about which method to use is usually made between the Architect/Designer, the Project Owner and the Energy Efficiency assessor. Factors that affect that decision are usually to do with the building design itself, something your Energy Efficiency assessor can advise you on.

So here’s the menu!  Get in touch with us if you’re still having trouble deciding…

1. The “Deemed To Satisfy” (DTS) Report

Often referred to in the industry just as a ‘Section J’ report, this is the basic assessment method used for simple commercial buildings.  It compares the Energy Efficiency elements of the building design to a series of benchmark requirements  listed in the NCC.  For example, under the DTS method, roofs in most climate zones must achieve a minimum R 3.7 insulative value.  Similar requirements apply to roof colour, floors, walls, glazing and other building elements.  If a building meets or exceeds these minimum requirements, it is ‘deemed to satisfy’ the NCC Energy Efficiency Performance Requirement.

The DTS method is the least flexible of the assessment methods (the specified DTS requirements have to be met), but it is by far the simplest and cheapest assessment method.

For standard and simple commercial buildings, DTS is the way to go.

2. JV3 Report 

A JV3 assessment allows much more flexibility in building design than the DTS method.  It is typically used for buildings that have complex or unusual features, or where specific DTS requirements are unwanted.  Common situations where the JV3 assessment method is used include:

• The Designer/Architect would like to remove the DTS requirement for underfloor insulation.
• A dark roof colour is preferred.
• Buildings with large areas of glazing (>25% glazing can be a useful rule of thumb for when a building may benefit from a JV3).

A JV3 assessment is more detailed than a DTS assessment.  In a JV3 two detailed models are built for the design – one model of the building which complies with the DTS requirements, and a second model which is constucted with the actual proposed design.  (For example, the proposed building might ease the glazing requirements relative to DTS requirements, but offset this by adding extra roof or wall insulation.) Thermal calculations from the two models are compared to ensure that the proposed building will (1) use the same or less energy than the reference (DTS) building, and (2) be thermally comfortable for the occupants.

Because of this modelling work, JV3 assessments are more time consuming and more costly – but they allow designers to incorporate or remove features that might not be possible using DTS.

3. NABERS Rating

Using the National Australian Built Environment Rating System (NABERS) assessment method, a building is given a star rating based on both its initial design, and also its ongoing operation practices. NABERS can only be used for building classes 2, 3, 5 and 6 (apartments, hotels etc., offices and shopping centres)

NABERS ratings can play an important role in marketing a building to clients, or complying with government requirements for larger buildings (e.g. https://www.cbd.gov.au/). However, carrying out a NABERS assessment is a significant undertaking and also requires the building owner to adopt ongoing commitments for the operation of the building during the life of its operation. For these reasons, NABERS ratings are typically conducted for CBD office towers, large shopping centres, or other larger buildings that can justify the ongoing management costs of administering those building requirements.

4. Green Star Rating

Green Star is an internationally recognised sustainability rating system.  It entails detailed evaluation of not only the building fabric, but all aspect of the building design and fitout.  Buildings are given a rating of 1 to 6 stars, with 6 stars indicating world leading sustainability in design.

Similar to NABERS, Green Star ratings are an important statement about a building’s sustainability credentials; however they are not a trivial undertaking – they are typically (but not exclusively) conducted on larger buildings, where the more significant assessment costs are proportionate to the building being assessed.

There are a couple of other assessment methods in the NCC (Verification using a reference building, and Verification of Building Envelope Sealing), but these are less common and used for specialised applications.

Frequently Asked Questions