There are two approaches available for the sole-occupancy units of residential buildings in J7D3(1)(a).They are a lamp power density approach or an illumination power density approach. The former is simpler while the latter provides considerably more flexibility for a dwelling with sophisticated lighting control systems. 5 W/m2 for inside a dwelling is the criterion in both approaches.

Lamp power density is the simpler means of setting energy consumption at an efficient level for sole-occupancy units of Class 2 buildings or a Class 4 part of a building. It is a defined term and is calculated by adding the maximum power ratings of all the permanently wired lamps in a space and dividing this sum by the area of the space. With this approach there are no concessions for using timers, motion detectors or other control devices.

If the illumination power density approach is used the 5 W/m2 can be increased by dividing it by the illumination power density adjustment factor in Table J7D3b where applicable. This more complex approach has been included as an increasing number of dwellings are using sophisticated control systems in order to reduce their energy consumption.

Lamps plugged into general purpose socket outlets are excluded through the definition of lamp power density and illumination power density because of the difficulty in regulating such portable appliances.

When illumination power density and one or more control devices are used, the adjustment factor is only applied to the space(s) served by the control device. The adjusted allowance for this space is then combined with the allowances for the remaining spaces using an area weighted average, which subsequently increases the allowance provided in J7D3(1)(a)(i) or (ii).

The area of the space refers to the area the lights serve. This could be considered a single room, open plan space, verandah, balcony or the like, or the total area of all these spaces.

To comply with J7D3(1)(a), the design lamp power density or design illumination power density must be less than or equal to the allowance. Trading of allowances between J7D3(1)(a)(i) and (ii) is not permitted.

J7D3(1)(a)(ii) includes outdoor living spaces such as verandahs, balconies, patios, alfresco spaces or the like that are attached to a sole-occupancy unit of a Class 2 building or Class 4 part of a building.

J7D3(1)(c) requires the power of the proposed installation to be used and may mean the light fittings be specified or some other administrative condition be applied.

J7D3(1)(d) requires the less efficient halogen lamps to be separately switched from fluorescent lamps. This is because the halogens may not be needed all the time but would have to be on if they were controlled by the same switch as the more efficient fluorescent.

J7D3(2) covers other building classifications. Requirements for these types of buildings are more detailed than the requirements for sole-occupancy units of Class 2 buildings or a Class 4 part, in order to cater for the greater range of applications.

Where lamp power density or illumination power density may be used for sole-occupancy units in Class 2 buildings or a Class 4 part of a building, only illumination power density (IPD) can be used to measure compliance for all other applications.

Lighting in non-residential commercial buildings is progressively moving towards the use of LED lamps for general lighting and for special lighting. At present other lamps are available, but because of the shift to LED lamps for general lighting, the illumination power density levels in Part J7 reflect this newer technology. The aggregated design illumination load is the maximum load in the lamp’s operational cycle.

J7D3(2)(a) describes the process for determining the illumination power allowance for artificial lighting, however it does not apply to the sole-occupancy units of a Class 2 building or a Class 4 part of a building.

The maximum values in Table J7D3a have been derived on the basis of a lighting design complying with the recommendations of AS 1680 for the nature of the task, including an allowance for a safety margin in design and the physical limitation of placing a discrete number of fittings in a uniform array. The maintained illuminance will be designed to suit the use of the area and again is based on the illuminance levels in AS 1680 or an equivalent document from an overseas standards organisation. However, the levels are not being controlled by Section J; only the power allowance for achieving the desired illuminance.

Guide Table J7D3 shows how some of the illumination power density values correspond to the lighting levels of AS 1680. The allowance is for the power supply to the lighting.

The values have been generally set at a level that can be achieved with reasonable surface reflectances, direct (rather than indirect) lighting, and low loss control gear. The use of the space has also been taken into account. However, Performance Solutions, developed to the satisfaction of the local building control authority, can be used for spaces that have complex or specific lighting needs. AS 1680.1 includes scenarios of where it may be appropriate for higher illumination levels. Where higher illumination levels can be justified to the local building control authority, a Performance Solution based on the notes to Table J7D3a could be developed.

Alternatively, energy saved by more efficientbuilding services or through the installation of on-site renewable energy systems may also be used to increase the allowances for lighting, again subject to the approval of the local building control authority.

There are two levels for offices. General open areas that are lit to more than 200 lx may use 4.5 W/m2. For offices lit to less than 200 lx, where task lighting is intended to supplement the general lighting, the maximum for the generallighting is only 2.5 W/m2.

The table provides values based on the illuminance level.

It is recognised that there are many variables in lighting that limit the ability to achieve the maximum illumination power density. One is the size of the room and so note 2 of Table J7D3a explains how the illumination power density may be increased for small rooms. A further series of adjustment factors have been included in Table J7D3b and Table J7D3c that allow credit for additional energy control devices or to allow the use of high Colour Rendition Lights.

The adjustment factors are applied to the maximum illumination power density in Table J7D3a. This means that if a designer chooses to use a less efficient light source or luminaire, compliance can be achieved by the use of a supplementary control device such as an occupancy sensor or photoelectric device.

Occupancy sensors representant efficient way of tailoring the lighting to the usage of the space. The fewer lights that are controlled by an individual sensor the greater the energy saved,however, there is less cost saving on the energyto offset the cost of the sensor. Therefore, there is a graduated scale of adjustment factors for the area of lights controlled.

For lecture theatres,auditoria and large spaces of transient usage, the contribution of detectors should be assessed using a Performance Solution rather than the Deemed-to-Satisfy Provisions.