All Commercial builds require a Section J Energy Assessment to ensure that the building and its services have features that facilitate the efficient use of energy appropriate to the function and use of the building, the geographic location and so on.
There are three main assessment methods allowed under the NCC2016 for Section J Compliance.
1. Verification Using a Reference Building (also known as JV3)
In this method, the estimated annual energy consumption of the proposed building is compared with the annual energy consumption of a reference building. If the proposed building’s energy consumption is not more than the reference building, it is deemed a pass. The reference building’s specifications are obtained by using the Deemed to Satisfy Values for the Building Elements (e.g. floor, roof, glazing etc.), combined with additional details of the proposed building (such as usage, geographic location etc.).
2. Deemed to Satisfy Method or DTS (sometimes known as J0)
In this method, the performance requirements of Section J are satisfied by showing the proposed building complies with the minimum Deemed to Satisfy Requirements of Section J0. The following elements are assessed individually and minimum levels of insulation, tinting, wattage etc. are specified by the Energy Assessor:
- Building Fabric (Roof and Ceiling, Envelope Walls, Floor)
- Glazing
- Building Sealing
- Air-conditioning
- Artificial Lighting
- Heated Water Supply
- Energy Monitoring
3. An Alternative Performance Solution to JV3
While option (1) above is technically a Performance Solution, alternative methods of demonstrating compliance to the Performance Requirements are also allowed, such as one that uses a combination of JV3 and J0, or expert judgement for example.
When is Section J Deemed to Satisfy the best approach to use?
A qualified Energy Assessor will be able to determine if a DTS Assessment is right for your project. However, here are some general aspects to consider:
- A Section J DTS Assessment will always be simpler and cheaper to obtain, because it does not involve costly and time-consuming computer simulation of the proposed building and the reference building. Upfront savings of thousands of dollars can be achieved here.
- The levels of insulation and glazing requirements can be easily determined in a DTS Assessment, and so the building materials can often be calculated and costed much earlier in the project, giving certainty to designer and client.
- There are certain constructions and designs that lend themselves to a DTS Assessment, such as slab-on-ground construction, a simple building envelope design, the presence of certain eave widths etc. Modifications to existing buildings that trigger a Section J Assessment are also good candidates for a DTS Assessments.
- While a JV3 Assessment will always result in a more Energy Efficient Building, it is worth remembering that the client is always able to go above the minimum standards specified in a DTS Assessment, and use a general understanding of Energy Efficiency principles to increase the ceiling insulation above the minimum required, and as costs allow.
When is a Section J DTS Assessment NOT the best approach to use?
A JV3 Assessment will always result in a more Energy Efficient building than one that follows the DTS minimum requirements. Sometimes this difference will not be significant for the client, however other times it will.
If a design needs to ‘trade-off’ poorly performing elements with better performing elements in a design (for example, a lot of West-facing glazing could be traded off with higher ceiling insulation) then a JV3 Assessment is the way to go.
As stated above, a qualified Energy Assessor will be able to determine which is the best way to go for your project. Contact BERA for advice and a no-obligation fee proposal on your next project.