Lighting : LIGHTING Feb-Mar 2018
30 LIGHTING MAGAZINE | February/March 2018 Table J6.2a also provides a formula for adjustment factors based on Room Aspect Ratio (RAR). The RAR adjustment factor provides the means to increase the maximum IPD applied to a room based on the size and shape of the space. The RAR is very effective in increasing the maximum allowable IPD for small rooms and for rooms that have high ceilings. Table J6.2b provides adjustment factors for lighting controls. If an automatic lighting control system is included in the design these adjustments factors provide the means to increase the maximum allowable IPD of that space. Once the RAR and the lighting controls adjustment factors have been applied the increase of the maximum IPD from that found in Table J6.2a can be extremely significant. The last three parts of Section J provide design requirements for the application of lighting controls, display lighting and building perimeter lighting. PROPOSED CHANGES FOR SECTION J6, NCC 2019 Methodology Table J6.2a of Section J6 provides maximum Illumination Power Density (IPD) requirements for target illuminance levels, for a list of space types and the associated recommended illuminance levels provided in AS/NZS1680.2 for those spaces types. Using AGi32 we simulated the illuminances of these space types from fluorescent and metal halide luminaires for various room aspect ratios (RARs) and illuminance targets drawn from AS/NZS1680.2 . We repeated the simulations substituting LED luminaires commonly used in commercial and industrial installations in 2017. The number of variables associated with a range of designs prevented the inclusion of decorative or indirect lighting. This was the starting point for further analysis and updates based on industry response. A detailed description of the methodology used in this analysis is given in a paper which was presented at the AIRAH Australian Building Simulation conference in November 2017 – Modelling for potential increases in IPD stringency in Section J6, which can be accessed at: http://www.airah.org. au/Content_Files/Conferences/2017/Building-simulation/ ABSC2017_TP_CynthiaJolley-Rogers.pdf Results The top row of Table 1 shows the maximum IPD from NCC 2016. Rows 2 and 3 show the IPD results achieved in the simulations with pre-LED technology and with LED technology for each of the illuminance targets (lux levels) recommended in AS/NZS1680. From these simulation results it was determined that the current code requirements could be readily surpassed with pre-LED technology, and that the use of LED fittings allows the extent of improvement to be increased further. The bottom row of Table 1 shows the proposed new maximum IPDs based on the simulation results. The recommended new max IPD were selected because they were typical of IPD results achieved in rooms with an RAR > 1.5 . IPDs achieved in rooms with an RAR < 1.5 were within the range to achieve the new max IPD with RAR adjustment calculations applied. The proposed maximum IPD updates Table 2 (see page 32) shows Table J6.2a from the NCC with the existing and proposed maximum IPD requirements. The proposed maximum IPD listed in Table 2 are all derived from the recommended new maximum basic IPD in Table 1 and also show the updated IPD for corridors, amenities and car parks. Application of adjustment factors It should be noted when reviewing the maximum IPD figures in Table J6.2a that significant increases in the maximum IPD will be achieved through the application of adjustment factors. No change has been made to the adjustment for room aspect ratio, however the adjustments for controls have been increased and adjustments have been added for lighting quality. Table 1. The IPD results from energy actions initial analysis Item 40 lux 80 lux 160 lux 240 lux 320 lux 400 lux 600 lux Retail 250- 500 lux Existing max basic IPD 6 5 7 8 9 10 15 22 Base case Fluorescent, CFL & MH max basic IPD 1.58 2.16 4.03 6.3 7 8.5 14 22 LED max basic IPD 0.83 1.04 2.3 2.9 4.2 5.8 9.6 13.8 Recommended new max basic IPD 1 1.5 2.5 3 4.5 6 10 14 The RAR adjustment factor provides the means to increase the maximum IPD applied to a room based on the size and shape of the space. The RAR is very effective in increasing the maximum allowable IPD for small rooms and for rooms that have high ceilings.
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