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Obtrusive light checker

Check outdoor light at a boundary window by AS/NZS 4282.

AS/NZS 4282

Reads AS/NZS 4282:2023. Tables checked 1 Oct 2026.

Try a job 7

Each job fills in example values. Replace them with your values.

Inputs

Worked example with the default inputs. The live calculator replaces it when the page loads.

Environmental zone
A2, Low district brightness
During the curfew
No
Distance to the boundary
10 m
Window centre height
1.5 m
Luminaires
1 row

Vertical illuminance at the window

47.67lx

Vertical illuminance limit
5lx
Greatest intensity toward the window
3,143cd
Intensity limit per luminaire
7,500cd
Upward light ratio
0.020
Upward light ratio limit
0.01

This result is a design aid. Verify it against the current standard.

Calculation steps

  1. Environmental zoneA2, Low district brightness

    AS/NZS 4282:2023 Table 3.1

  2. PeriodOutside the curfew

    AS/NZS 4282:2023 Cl 3.2.4

  3. Maintenance factor1

    AS/NZS 4282:2023 Cl 3.2.2

  4. Window centre10 m out, 1.5 m up

    AS/NZS 4282:2023 Cl 3.3.1.3

  5. Peak intensity I04,775cd
  6. Angle off the beam axis35.8°
  7. Intensity toward the window3,143cd

    AS/NZS 4282:2023 Cl 3.3.1.3

  8. Ev at the window, 2 × 23.836 lx47.67lx

    AS/NZS 4282:2023 Cl 3.3.1.3

  9. Vertical illuminance at the windowResult47.67lx

    AS/NZS 4282:2023 Cl 3.3.1.3

  10. Vertical illuminance limit5lx

    AS/NZS 4282:2023 Table 3.2

  11. Greatest intensity toward the window3,143cd

    AS/NZS 4282:2023 Cl 3.3.1.3

  12. Intensity limit per luminaire, Level 17,500cd

    AS/NZS 4282:2023 Table 3.3

  13. Lumens above the horizontal400lm

    AS/NZS 4282:2023 Cl 3.3.1.8.2

  14. Total lumens20,000lm

    AS/NZS 4282:2023 Cl 3.3.1.8.2

  15. Upward light ratio0.02

    AS/NZS 4282:2023 Cl 3.3.1.8.2

  16. Upward light ratio limit0.01

    AS/NZS 4282:2023 Table 3.2

About this calculator

How this is calculated

The tool estimates the light a floodlight or bollard puts on a neighbour window. It checks the result against AS/NZS 4282:2023.

  1. Zone and period. You pick the environmental zone, A0 to A4, and whether the curfew applies. Table 3.1 defines the zones. Cl 3.2.4 sets the curfew period.
  2. Intensity toward the window. The tool takes the beam angle and the tilt of each luminaire. It finds the angle off the beam axis. It then reads the intensity at that angle from a simple lobe (Cl 3.3.1.3).
  3. Vertical illuminance. For each luminaire, it divides the intensity by the squared distance to the window. It applies the maintenance factor of Cl 3.2.2 and adds the luminaires.
  4. Illuminance limit. Table 3.2 gives the vertical illuminance limit for the zone and period.
  5. Intensity limit. Table 3.3 gives the intensity limit for one luminaire. The tool uses the Level 1 value.
  6. Upward light ratio. Cl 3.3.1.8.2 gives the share of lumens above the horizontal. Table 3.2 gives the limit.
StepTable or clauseWhat it decides
ZoneAS/NZS 4282:2023 Table 3.1The environment class of the site
Illuminance at the windowCl 3.3.1.3The vertical light on the window
Illuminance limitTable 3.2The most light allowed at the window
Intensity limitTable 3.3The most intensity from one luminaire
Upward light ratioCl 3.3.1.8.2The share of light sent above the horizontal

Worked example

  • Two floodlights at a window 10 m away. Each unit gives 10,000 lm, mounted at 6 m and tilted 30°. Zone A2 applies outside the curfew. The tool gives 47.67 lx at the window against a limit of 5 lx, so it fails. The intensity of 3,143 cd is under the limit of 7,500 cd. The upward light ratio is 0.020 against 0.01, so that check also fails.

Limits

The result is a point-source estimate. A site measurement rules. The tool uses a lobe in place of the photometric file from the maker. Use the maker intensity table when you have it. Only direct light counts. Reflected light and obstructions are not modelled.

Level 1 intensity applies. Level 2 needs a precedent from existing lighting (Cl 3.2.5). Tilting a luminaire can raise the upward fraction, so type the value at the aiming angle.

See also: Obtrusive light and the 4282 zones, Car park floodlight obtrusive light at a boundary and the lighting lumen tool.

Questions

Each answer describes what this tool calculates. The result is a design aid. Verify against the current standard.

Which environmental zone applies to my site?

The zone follows the planning zoning of the area, future zoning included. Most suburbs are A3, sparse rural and semi-rural areas A2, and town centres and industrial areas A4. Ask the council where it is unclear.

What is the curfew?

The curfew is the late-night period when the lower limits apply. Unless the council or the consent sets other hours, take it as 11 p.m. to 6 a.m. Turn the curfew on to check the lights that stay on through it.

Why does the tool call its answer an estimate?

It treats each row of luminaires as one point with a smooth beam. A real floodlight has its own intensity table, and a site has walls, trees and reflections. Use a photometric calculation or a site measurement for the final answer.

What is the upward fraction of a luminaire?

The share of its lumens that leaves above the horizontal at the aiming angle. A full cut-off luminaire mounted level has 0. Tilting a floodlight up can raise it, so take the figure from the maker’s data at the installed tilt.

What are Level 1 and Level 2 intensity limits?

Outside the curfew, Table 3.3 gives two intensity limits. Level 1 applies to new lighting. Level 2 is higher, and needs a precedent from existing lighting nearby. The tool checks Level 1.

Clauses and tables this tool reads

Every clause and table, with how each was verified

Tables last checked on 1 Oct 2026.

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