What is a BCA Section J JV3?
Under the broader spectrum of the NCC, volume 1 of the BCA contains Section J which has a number of provisions a developer must adhere to, to satisfy energy efficiency requirements of the building code of Australia. Section J was introduced as a result of energy emitters not being sufficiently encouraged to conserve energy and use sustainable means of usage. The Deemed-to-Satisfy (‘DTS’) provisions are a basis for assessing a building’s energy efficiency rating which sets the minimum requirements of the BCA in all parts and sections including the section J. However, if a development does not meet these standards, or if a developer wishes to change some aspects about the building’s design, alternative assessments can be considered outside of the DtS provisions. An alternative solution which the appropriate authority accepts for determining compliance with the Performance Requirements, can be derived through conducting a JV3 Alternative Verification Method.
TThe JV3 verification method can also be used as a performance solution to demonstrate compliance with the Performance Requirement JP1 which states -
JP1 A buildings, including its services, must have, to the degree necessary, features that facilitate the efficient use of energy appropriate to:
- the function and use of the building and services
- the internal environment
- the geographic location of the building
- the effects of nearby permanent features such as topography, structures and buildings; and
- solar radiation being- (i) utilised for heating; and (ii) controlled to minimise energy for cooling
- the sealing of the building envelope against air leakage
- the utilisation of air movement to assist heating and cooling
- the energy source of the services
Conditions for JV3 application instead of DTS
The JV3 assessment method involves a comparative analysis which aims to demonstrate that an alternative building solution would be better or at least equivalent to the DtS provisions.
JV3 is most useful to all Class 3, 5, 6, 7, 8 and 9 buildings because they are more likely to be air-conditioned and artificially lit than dwellings. Therefore, it is necessary to consider the plant and equipment as JV3 does, rather than simply the building’s external envelope as the DtS provisions are limited to. The JV3 method allows a “trade off” between certain elements, such as a reduction in the energy efficiency of the services in the building, provided there is an increase in the energy efficiency of the fabric or envelope of the building.
When conducting a JV3 analysis, a comparator DtS complying building is used to determine whether the alternate solution in the JV3 is providing the same level of energy efficiency as that of the DTS comparator. Ultimately, the JV3 alternate solution must satisfy the NCC performance requirements.
The intention of the JV3 method is to demonstrate that an alternative building solution meets relevant performance requirements of the BCA section J- even if one or more of its elements do not comply with the prescribed requirements of the deemed to satisfy provisions. The JV3 Method can allow for innovation and better use of a building’s fabric and services in order to make the building more energy efficient.
To achieve this level of compliance for the alternative solution, a computer-simulated thermal modelling process is undertaken - which is not conducted for a DtS compliant building. There are no trade-offs when it comes to compliance with the DtS checklist, and each element must comply independently. It may initially seem like it is easier to retain compliance with the DtS checklist, but almost every time, it will end up costing more and won’t be as efficient as a building which has been doing a JV3 alternative solution assessment.
JV3 cost savings
A DtS compliant development must include a number of specifics, pertaining to insulation which must comply with Parts J1.2, J1.3, J1.5 and J1.6 of the NCC. The glazing must also be in accordance with DtS glazing allowances, which depends on the relevant climate zone of the development, as well as the façade, glazing and shade elements. Roof lights are also restricted to no larger than 5% of the total floor area.
Because these specifics are weighted against flexibility, these stringent requirements mean that overall construction costs will be increased and in some cases, the overall functionality and design intention of a project can be compromised by these provisions. These restrictions are not present in a JV3 assessment since all the elements of the building’s design are factored into the computer model and the most cost effective and feasible building solution can be found for the whole building by educated trade off between those elements.
A JV3 assessment is capable of achieving a building solution without essentially complying to all of the DtS requirements. While it may seem like the initial cost of conducting a JV3 assessment is financially burdensome, it in fact formulating a JV3 assessment allows a noticeably larger saving during the construction phase of the building. It also delivers a more uniform and practical building solution particularly for glazing requirements of the BCA section J.
JV3 assessment process
The basic approach for conducting a JV3 alternative solution assessment is to use computer simulation to demonstrate that the annual energy consumption of the proposed alternative solution is equivalent or better than the annual energy consumption of a reference building which complies with all the DtS provisions of section J of the BCA.
The performance of the alternative solution must be better than the performance of the reference building when simulated with the DTS compliant services, as well as with the alternative solution proposed services. This essentially means that we are required to have several software modeling and simulation runs in a JV3 assessment, explained below.
Software run 1: In this step, the annual energy consumption of a reference building, which is a DtS compliant building based on the JV3 criteria, is being calculated.
Software run 2: In this step, the annual energy consumption of the alternative design solution building is calculated by computer modeling which can be either by the building’s own criteria or the ones detailed under Specifications JV of the JV3 section.
Software run 3: This is the same as run 2 but the services must be modelled as the ones in the run 1 which are DtS compliant services.
The annual energy consumption results of run 1 should be equal or less than both run 2 and 3 in order to demonstrate compliance of a building under JV3 provisions. This essentially means that the thermal performance of the building’s envelope could not be “traded-off” for more energy efficient building services however JV3 permits the trade-off to go the other way i.e. we can have better performing building envelopes and lower performing services compared to the DtS and our alternative solution still complies with the BCA Section J requirements. The rationale behind this approach is that: building services may change over the lifetime of a building, or a lack of maintenance may cause the performance of the services to diminish over time. However once the passive energy efficiency requirements for the building envelope elements are in place, they generally maintain their original performance level for the lifetime of a building.
What should a JV3 include?
A JV3 assessment requires a 3D model of the building with the location, orientation and climate information of the surroundings to be created using building energy modeling computer softwares which have certain acceptance criteria and pass necessary tests.
Other factors such as the lighting, temperature, usage patterns and occupancy patterns of the building are also considered in order to calculate the annual energy consumption of a proposed development. This is then compared to the annual energy consumption of a reference building computer model- which is a model created by all the elements as they are required by the DtS provisions.