Part J0 Energy efficiency
J0.0 Deemed-to-Satisfy Provisions
The Deemed-to-Satisfy Provisions described are limited to the most common forms of construction and the simplest forms of buildings. It is expected that the more innovative construction techniques and the more complex buildings will be designed and assessed using a performance approach.
The measures have been developed using a cost-effectiveness model.
A major consideration in developing the measures was the likelihood of a building being heated or cooled by an air-conditioning system, and whether the Deemed-to-Satisfy Provisions should assume this to be the case, or only apply the provisions if a heating or cooling system is installed. It is recognised that most Class 3, 5, 6 and 9 buildings and some Class 7 and 8 buildings are heated or cooled, and this is the basis of the provisions. Consideration was also given to the fact that although the first owner may be prepared to ‘manage’ their building in the appropriate manner, the next owner or tenant may not, and instead may install air-conditioning.
Because of the performance-based structure of the NCC, a Performance Solution may be proposed instead of the Deemed-to-Satisfy Provisions.
J0.1 Application of Section J
for artificial lighting and power, Part J6; and
for facilities for monitoring, Part J8.
To clarify which provisions of Section J apply to dwellings and which provisions apply to other buildings.
J0.1 explains which provisions need to be complied with for—
- a sole-occupancy unit of a Class 2 building or a Class 4 part; and
- all other classifications.
J0.1(a) explains that, for the thermal performance of the building fabric, there are two paths for compliance depending on whether the building contains dwellings (i.e. sole-occupancy units in a Class 2 building or a Class 4 part) or not. For the fabric of dwellings, compliance must be in accordance with J0.2 while for other building classifications, compliance must be in accordance with Parts J1 and J3. For services, all buildings must comply with Parts J5 to J8.
The means of compliance is explained in Figure J0.1.
J0.2 Heating and cooling loads of sole-occupancy units of a Class 2 building or a Class 4 part
The sole-occupancy units of a Class 2 building or a Class 4 part of a building must—
for reducing the heating or cooling loads—
collectively achieve an average energy rating of not less than 6 stars, including the separate heating and cooling load limits; and
individually achieve an energy rating of not less than 5 stars, including the separate heating and cooling load limits,
using house energy rating software and the load limits specified in the ABCB Standard for NatHERS Heating and Cooling Load Limits.
for general thermal construction, comply with J1.2; and
for building sealing, comply with Part J3.
To clarify how the shell of a sole-occupancy unit of a Class 2 building or a Class 4 part are to comply.
In order to reduce the heating or cooling loads, the fabric of a sole-occupancy unit of a Class 2 building or a Class 4 part must achieve the required house energy rating and the separate heating and cooling load limits. Information about building modelling using house energy rating software is available at www.nathers.gov.au. The applicable heating and cooling load limits are published in the ABCB Standard for NatHERS Heating and Cooling Load Limits, which can be accessed at www.abcb.gov.au.
It must also comply with a few general Deemed-to-Satisfy Provisions relating to the insulation standard, installation of insulation, thermal breaks, sealing, etc.
The measures for a sole-occupancy unit of a Class 2 building or a Class 4 part of a building are similar to those adopted for Class 1 buildings in BCA Volume Two - Housing Provisions. There are several reasons for this, including:
- Many Class 2 and 4 buildings are very similar in thermal performance to Class 1 buildings.
- Being dwellings, there are similarities in their use with high occupancy at night.
- Having all types of dwellings achieving comparable performance provides a consistent approach.
Importantly, as per Class 1 buildings, a sole-occupancy unit of a Class 2 building and a Class 4 part of a building must satisfy both the required star rating and the corresponding heating and cooling load limits. The star rating is based on the combined heating and cooling load of the dwelling, whereas compliance with the heating and cooling load limits is dependent on the separate heating and cooling loads of the dwelling.
J0.3 Ceiling fans
be permanently installed; and
have a speed controller; and
serve the whole room, with the floor area that a single fan serves not exceeding—
15 m2 if it has a blade rotation diameter of not less than 900 mm; and
25 m2 if it has a blade rotation diameter of not less than 1 200 mm.
Further information about house energy rating and heating and cooling load limits can be obtained on the website of the Nationwide House Energy Rating Scheme.
To set the minimum requirements for ceiling fans.
A ceiling fan may be required to provide high air movement as part of a house energy rating software solution and two sizes of fans are described in terms of their diameter and the floor area they serve.
J0.4 Roof thermal breaks
For compliance with J0.2(c), a roof that—
has metal sheet roofing fixed to metal purlins, metal rafters or metal battens; and
does not have a ceiling lining or has a ceiling lining fixed directly to those metal purlins, metal rafters or metal battens,
must have a thermal break, consisting of a material with an R-Value of not less than R0.2, installed at all points of contact between the metal sheet roofing and its supporting metal purlins, metal rafters or metal battens.
J0.5 Wall thermal breaks
For compliance with J0.2(c), a wall that—
does not have a wall lining or has a wall lining that is fixed directly to the same metal frame; and
has lightweight external cladding such as weatherboards, fibre-cement or metal sheeting fixed to a metal frame,
must have a thermal break, consisting of a material with an R-Value of not less than R0.2, installed at all points of contact between the external cladding and the metal frame.