NCC 2022 Volume One - Building Code of Australia Class 2 to 9 buildings
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J3

Part J3 Elemental provisions for a sole-occupancy unit of a Class 2 building or a Class 4 part of a building

Part J3 Elemental provisions for a sole-occupancy unit of a Class 2 building or a Class 4 part of a building

Introduction to this Part

This Part contains Deemed-to-Satisfy Provisions (elemental) for compliance with Part J1. It sets out provisions for the insulation of building fabric and the energy efficiency of domestic services of a sole-occupancy unit of a Class 2 building or a Class 4 part of a building.

Notes

From 1 May 2023 to 30 September 2023 Section J of NCC 2019 Volume One Amendment 1 may apply instead of Section J of NCC 2022 Volume One. From 1 October 2023 Section J of NCC 2022 Volume One applies.

Notes: New South Wales Section J Energy Efficiency

  1. For a Class 2 building or a Class 4 part of a building, where a relevant development consent or an application for a complying development certificate requires compliance with a BASIX Single Dwelling or Multi Dwelling Certificate issued under Version 3.0 or earlier, NSW Section J of NCC 2019 Volume One Amendment 1 applies.
  2. For a Class 2 building or a Class 4 part of a building, where a relevant development consent or an application for a complying development certificate requires compliance with a BASIX Single Dwelling or Multi Dwelling Certificate issued under Version 4.0 or later, Section J of NCC 2022 Volume One applies.
  3. For a Class 2 building or a Class 4 part of a building, where a relevant development consent or an application for a complying development certificate requires compliance with a BASIX Alterations and Additions Certificate, NSW Section J of NCC 2019 Volume One Amendment 1 applies.

Deemed-to-Satisfy Provisions

New for 2022

State variations

To clarify that J1P1 to J1P4 will be satisfied if compliance is achieved with Parts J2 to J9.

J3D1 Deemed-to-Satisfy Provisions

Where a solution is proposed to comply with the Deemed-to-Satisfy Provisions, J3D1 stipulates that compliance with nominated elements of Parts J2 to J9 achieves compliance with J1P1 to J1P4.

Where a Performance Solution is proposed, the relevant Performance Requirements must be determined in accordance with A2G2(3) and A2G4(3) as applicable. (See commentary on Part A2).

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.

New for 2022

State variations

To clarify Part J3 applies to the building elements that make up the external fabric and domestic services of a sole-occupancy unit in a Class 2 building and a Class 4 part of a building.

2019: J0.2

State variations

To clarify that J1P1 to J1P4 will be satisfied if compliance is achieved with Parts J2 to J9.

J3D1 Deemed-to-Satisfy Provisions

Where a solution is proposed to comply with the Deemed-to-Satisfy Provisions, J3D1 stipulates that compliance with nominated elements of Parts J2 to J9 achieves compliance with J1P1 to J1P4.

Where a Performance Solution is proposed, the relevant Performance Requirements must be determined in accordance with A2G2(3) and A2G4(3) as applicable. (See commentary on Part A2).

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.

2019: J0.3

State variations

To set the minimum requirements for ceiling fans in a sole-occupancy unit of a Class 2 building or a Class 4 part.

J3D4 Ceiling fans in a sole-occupancy unit of a Class 2 building or a Class 4 part of a building

A ceiling fan may be required to provide high air movement as part of a house energy rating software solution and several sizes of fans are described in terms of their diameter and the floor area they serve.

2019: J0.4

To set the minimum requirements for thermal breaks in roofs on a sole-occupancy unit of a Class 2 building or a Class 4 part of a building.

J3D5 Roof thermal breaks of a sole-occupancy unit of a Class 2 building or a Class 4 part of a building

Thermal bridging can compromise the thermal performance of a building, and metal roofs are particularly susceptible to this problem. To address this, J3D5 mandates the inclusion of thermal breaks in specific types of metal roofs. A roof must have a thermal break if it features metal sheet roofing directly affixed to metal purlins, rafters, or battens, and does not have a ceiling lining or has a ceiling lining fixed to a member of the metal roof frame (including a ceiling fixed to metal purlins, rafter or battens). These provisions address the localised heat transfer through poor detailing and apply in addition to the thermal bridging mitigation provisions of J3D7.

The thermal break material must have an R-Value of at least R0.2. This adds an insulating layer between the metal roof and its supporting structures, effectively reducing heat transfer. Roofs constructed with insulated sandwich panels are exempt from these requirements as sandwich panels limit thermal bridging.

2019: J0.5

To set the minimum requirements for thermal breaks in walls on a sole-occupancy unit of a Class 2 building or a Class 4 part of a building.

J3D6 Wall thermal breaks of a sole-occupancy unit of a Class 2 building or a Class 4 part of a building

The primary focus of J3D6 is to ensure that metal-framed walls forming part of the building envelope incorporate thermal breaks. A thermal break is an insulating material designed to reduce thermal conductivity and inhibit the flow of thermal energy between conductive materials. In simple terms, thermal breaks minimise heat transfer and improve the overall thermal performance of a building. These provisions address the localised heat transfer through poor detailing and apply in addition to the thermal bridging mitigation provisions of J3D78.

Specifically, J3D6 mandates that any metal-framed wall must have a thermal break with an R-Value of at least R0.2 at all points of contact between the external cladding and the metal frame. This requirement is applicable when the wall does not have a lining or when the lining is directly affixed to the metal frame. Moreover, J3D6 provision applies to walls clad with weatherboards, fibre-cement, or metal sheeting. Walls constructed using insulated sandwich panels are exempt from these requirements as sandwich panels limit thermal bridging.

New for 2022

State variations

To set the minimum requirements for insulating roofs and ceilings for Class 2 sole-occupancy units or a Class 4 part of a building.

J3D7 Roofs and ceilings of a sole-occupancy unit of a Class 2 building or a Class 4 part of a building

J3D7 sets varying minimum ceiling insulation R-Values depending on the roof construction, colour and ventilation levels, and the buildings location across different NCC climate zones. J3D7 also states that reflective insulation should have a surface emittance of not more than 0.05 and must be adjacent to a roof space of at least 20 mm. Additionally, in climate zones 3 to 8, the reflective insulation must be downward-facing to ensure it is effective.

There are multiple options to mitigate thermal bridging in metal-framed roofs, These provisions all aim to reduce the overall heat transfer through the metal framing so that it is approximately the same as an equivalent timber-framed structure. For pitched roofs with horizontal ceilings, options include achieving a specified Total R-Value or increasing the insulation R-Value between the ceiling frames, or adding a continuous insulation layer above or below the ceiling framing, or achieving the required ceiling insulation by stacking layers such that the top layer is oriented to cover the ceiling joist or bottom chord of the truss. For flat, skillion, or cathedral roofs, provisions are provided to either achieve specified Total R-Values in Table J3D7t or take mitigating actions specified in Table J3D7u. Thermal bridging provisions apply in addition to the thermal break provisions.

For ventilated roof spaces in climate zones 6, 7, and 8, continuous insulation placed above the primary insulation layer to mitigate thermal bridging must have a vapour permeance at least that of the primary insulation layer to avoid the build-up of condensation.

J3D7 also allows for compensation in instances where operational or safety concerns necessitate reduced ceiling insulation. Specifically, the loss of insulation must be offset as laid out in Table J3D7w. The provision also allows for reduced ceiling insulation R-Values near external walls, provided that thicker insulation is used elsewhere to compensate. This is in recognition of the fact that the roof space height typically reduces at the perimeter, where the roof meets the walls. 

Roofs constructed with insulated sandwich panels are not subject to these rules but must meet the minimum Total R-Value requirements stipulated in Table J3D7x.

Maximum solar absorptance requirements are also set to discourage the use of dark-coloured roofs in hot climates.

New for 2022

State variations

To set the minimum requirements for external walls of a sole-occupancy unit of a Class 2 building or a Class 4 part of a building.

J3D8 External walls of a sole-occupancy unit of a Class 2 building or a Class 4 part of a building

The thermal performance of external walls is crucial for the overall energy efficiency of a building and J3D8 addresses this by specifying the required Total R-Values based on climate zones and the ratio of the opaque external walls to floor area. For climate zones 1, 2, 3, 5, and 6, the required Total R-Value varies from R1.15 to R2.24 based on that ratio. For climate zones 4, 7, and 8 a minimum R2.24 is required, regardless of the wall-to-floor area ratio.

J3D8 also outlines how to determine the Total R-Value. For spandrel panels in curtain wall systems, Specification 38 should be followed. For all other walls, consult AS/NZS 4859.2. Lastly, J3D8 provides guidelines on the solar absorptance of external walls, which varies depending on the climate zone. Solar absorptance tables for different climate zones are provided to guide this.

New for 2022

State variations

To set the minimum requirements for wall glazing for Class 2 sole-occupancy units or a Class 4 part of a building.

J3D9 Wall-glazing construction of a sole-occupancy unit of a Class 2 building or a Class 4 part of a building

J3D9 details specifications for external wall-glazing construction in different climate zones. It sets the Total System U-Value — a measure of heat transfer — for wall-glazing constructions, indicating the maximum allowed values ranging from U1.4 in colder climates (zones 7 and 8) to U2.2 in warmer zones (1 to 5). The U-Value must be calculated according to Specification 37, ensuring a consistent method of measurement.

Furthermore, the provision sets a backstop on the minimum Total R-Value (thermal resistance) of the opaque wall components within a wall-glazing construction. This is dependent on what proportion the wall takes up in the entire construction. For instance, if the wall constitutes less than 80% of the wall-glazing construction, it must have a minimum R-Value of R1.0. If the wall comprises 80% or more, the R-Value must be according to what is specified for Class 3 buildings in Table J4D6a.

Solar admittance and solar absorptance are crucial factors in thermal comfort. Solar absorptance of an external wall must be in accordance with either Table J3D8a or J3D8b. The solar admittance values are confined by climate zone and must be calculated according to Specification 37. For colder climate zones (7 and 8), the glazing must have a Total System SHGC (Solar Heat Gain Coefficient) of at least 0.4.

New for 2022

State variations

To set the minimum requirements for floors of a sole-occupancy unit of a Class 2 building or a Class 4 part of a building.

J3D10 Floors of a sole-occupancy unit of a Class 2 building or a Class 4 part of a building

J3D10 addresses thermal performance requirements for different types of floors, paying special attention to floors above carparks or undercrofts. Underfloor insulation is obligatory for suspended concrete floors, with varying R-Values determined by climate zone and the nature of the space beneath the floor (e.g. enclosed or unenclosed carpark).

For concrete slab-on-ground with in-slab or in-screed heating or cooling systems, J3D10 mandates a minimum R-Value of 1.0 for insulation around the vertical edge of the slab's perimeter. Insulation requirements for in-screed heating or cooling systems that are solely used in bathrooms, amenity areas, or similar spaces do not apply.

In climate zones 6 to 8, minimum R-Value requirements are also set for around the perimeter and underneath slab-on-ground, regardless of in-screed heating or cooling, with R-Values depending on the climate zone. Waffle-pod slabs are exempt because of their inherent insulating properties.

Water resistance for insulation required around the slab's perimeter must be achieved. This insulation must also be continuous from the adjacent ground level to a minimum depth of 300 mm or at least the full depth of the vertical edge of the concrete slab, ensuring thermal performance is not compromised.

New for 2022

State variations

To set the minimum requirements for external winter glazing of a sole-occupancy unit of a Class 2 building or a Class 4 part of a building.

J3D11 External winter glazing of a sole-occupancy unit of a Class 2 building or a Class 4 part of a building

J3D11 addresses the thermal performance of external winter glazing in climate zones 2 to 8. The provision stipulates that the ratio of conductance (CU) to solar heat gain (CSHGC) for the glazing on each storey (including mezzanines) must not exceed the allowance outlined in Table J3D11a. To apply this provision accurately, you must refer to various additional resources:

  • the orientation sectors are to be determined according to Figure 13.3.2a of the ABCB Housing Provisions;
  • P/H values must be ascertained in accordance with Figure S37C7; and
  • if P/H values fall between those outlined in Tables J3D11b through J3D11g, you are to use the next highest P/H or interpolate.

This provision aims to balance the thermal performance of the glazing during the winter months, taking into account the varying conditions in different climate zones.

New for 2022

State variations

To set the minimum requirements for external summer glazing of a sole-occupancy unit of a Class 2 building or a Class 4 part of a building.

J3D12 External summer glazing of a sole-occupancy unit of a Class 2 building or a Class 4 part of a building

J3D12 covers the thermal performance of external summer glazing in climate zones 1 to 7. The total solar heat gain from the glazing must be within certain limits, calculated based on the floor area and constants obtained from Table J3D12a.

The formula used for this calculation involves several components, each with a specific role:

  • area of each glazing element;
  • Total System SHGC for each glazing element, capped at 0.7;
  • summer exposure factor for each glazing element, derived from Tables J3D12b through J3D12h; and
  • additional factors for bedrooms and unconditioned spaces, and for framing and flooring, taken from Tables J3D12i and J3D12j.

For proper implementation:

  • orientation sectors are to be determined in accordance with Figure 13.3.2a of the ABCB Housing Provisions;
  • P/H values must be found according to Figure S37C7; and

for intermediate P/H values, either use the next highest P/H or interpolate.

New for 2022

State variations

To set the minimum requirements for shading of a sole-occupancy unit of a Class 2 building or Class 4 part of a building.

J3D13 Shading of a sole-occupancy unit of a Class 2 building or a Class 4 part of a building

J3D13 comes into play when shading is necessary for compliance with either J3D11 (concerning external winter glazing) or J3D12 (pertaining to external summer glazing). The goal is to ensure effective shading solutions that contribute to energy efficiency, occupant comfort, and overall building performance.

J3D13 outlines two main types of acceptable shading solutions: external permanent projections and external shading devices.

External permanent projections examples include verandahs, balconies, fixed canopies, eaves, shading hoods, or carports. These projections must meet one of two criteria:

  • the external projection should extend horizontally on both sides of the glazing for a distance equal to or greater than the "projection distance P" specified in Figure S37C7 of the ABCB Housing Provisions; or
  • if the projection doesn't extend as described above, it should provide equivalent shading through features like reveals or similar architectural elements.

Alternatively, external shading devices such as shutters, blinds, or screens with blades, battens, or slats must be used. These devices must meet two essential criteria:

  • radiation restriction: The shading device must be capable of blocking or restricting at least 80% of the summer solar radiation. This ensures that the shading is effective in reducing heat gain inside the unit; and
  • operability: If the device is adjustable, it should be easily operable by building occupants, whether manually, mechanically, or electronically. The purpose is to allow occupants to adapt shading according to changing environmental conditions, thereby maximizing energy efficiency and comfort.
New for 2022

State variations

To demonstrate net equivalent energy calculations of a sole-occupancy unit of a Class 2 building or a Class 4 part of a building.

J3D14 Net equivalent energy usage of a sole-occupancy unit of a Class 2 building or a Class 4 part of a building

J3D14 sets an energy budget for the regulated energy used in the dwelling based on its floor area and location. The energy budget is intended to reflect the operating costs that will be incurred by the occupants, assuming that the building’s fabric also meets the minimum efficiency requirements. It incorporates a consideration of broader societal costs associated with the energy use. The provision also prescribes a method to calculate the energy use of each sole-occupancy unit to compare with the budget allowance.

The components of the energy usage calculation are:

  • Floor area factor: Calculated by multiplying the total floor area of the unit by an adjustment factor from Table J3D14a.
  • Main space and water heater efficiency: Obtained from the ABCB Standard for Whole-of-Home Efficiency Factors.
  • Swimming pool pump energy usage: Defined in J3D14(2) and based on swimming pool volume and a factor from Table 13.6.2c of the ABCB Housing Provisions. Only swimming pools dedicated to the individual sole-occupancy unit are considered, not common-area swimming pools.
  • Spa pump energy usage: Defined in J3D14(3) and based on spa volume and a factor from Table 13.6.2d of the ABCB Housing Provisions. Only spas dedicated to the individual sole-occupancy unit are considered, not common-area spas.
  • Installed photovoltaic capacity: The installed photovoltaic (solar panel) capacity allocated to the unit.
New for 2022

State variations

To demonstrate net equivalent energy usage with home energy rating software.

J3D15 Net equivalent energy usage for a sole-occupancy unit of a Class 2 building or Class 4 part of building – home energy rating software

J3D15 states that a sole-occupancy unit of a Class 2 building or Class 4 part of a building must achieve a whole-of-home rating of 50 or more when evaluated using house energy rating software. This software-based approach simplifies the process of assessing a unit's energy performance by using a comprehensive model to evaluate various parameters affecting energy consumption.

Table J4D6a Minimum wall Total R-Value - Wall area 80% or more of wall-glazing construction area
Climate zone Class 2 common area, Class 5, 6, 7, 8 or 9b building or a Class 9a building other than a ward area Class 3 or 9c building or Class 9a ward area
1 2.4 3.3
2 1.4 1.4
3 1.4 3.3
4 1.4 2.8
5 1.4 1.4
6 1.4 2.8
7 1.4 2.8
8 1.4 3.8
Table F8D5 Roof space ventilation requirements
Roof pitch Ventilation openings
<10° 25,000 mm2/m provided at each of two opposing ends
≥10° and <15° 25,000 mm2/m provided at the eaves and 5,000 mm2/m at high level
≥15° and <75° 7,000 mm2/m provided at the eaves and 5,000 mm2/m at high level, plus an additional 18,000 mm2/m at the eaves if the roof has a cathedral ceiling
Table Notes
  1. Ventilation openings are specified as a minimum free open area per metre length of the longest horizontal dimension of the roof.
  2. For the purposes of this table, high level openings are openings provided at the ridge or not more than 900 mm below the ridge or highest point of the roof space, measured vertically.
Figure S37C7 Permanent external shading – measurement of P, G and H
Figure 13.3.2a Orientation sectors
Figure Notes
  1. The orientation sector for a wall or glazing element is the sector that contains a line drawn perpendicular to the face of the wall or glazing element.
  2. This Figure is based on True North and all angles are measured clockwise from True North. Survey angles on site plans are usually marked in angles from True North. These angles can be used to establish True North for a particular site.
  3. Magnetic North, found by a magnetic compass, varies from True North over time and by different amounts in different locations. Magnetic North is not an acceptable approximation of True North.
  4. The eight orientation sectors shown in this Figure do not overlap at their boundaries. For example, north sector begins just clockwise after the NNW line and ends exactly on the NNE line. The start and end of other sectors are determined in a similar way, as indicated by the other curved arrows.