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Lighting Uniformity Explorer

Map the illuminance readings you took across a working plane as a grid, check the average against the AS/NZS 1680.2 target for the space, see the unevenness a single average hides, and read off the uniformity ratio for Assignment 1.

A lit space raises two questions: is there enough light on average, and is it spread evenly? They are different, and a space can pass one while failing the other.

For the amount, compare your average illuminance against the maintained-illuminance target AS/NZS 1680.2 recommends for the space type. For the evenness, use the uniformity ratio U0 = minimum ÷ average: near 1.0 the darkest spot is almost as bright as the typical one, while a low value means dark patches the mean conceals. EN 12464-1 (and AS/NZS 1680) expect U0 ≥ 0.60 across a task area such as a desk; a related, stricter ratio is diversity = minimum ÷ maximum. A space can hit its target average and still feel patchy, which the ratio reveals but the mean hides.

Pick your space type to load its target, then set the grid to match how you walked the space (e.g. 4 columns across the desk, 4 rows front-to-back) and type each reading in lux into the cell at that position. Leave a cell blank where you did not take a reading; blanks are ignored in the maths and shown empty on the map.

Values are in lux. Grid positions are relative, so orient it however you measured (e.g. top row nearest the window).
How these relate to the lighting standards (AS/NZS 1680, EN 12464-1)

Amount. AS/NZS 1680.2 sets a maintained illuminance per space type (the targets in the space-type list, from the Week 4 brief); the tool reports whether your average sits below, on, or above that range. It allows a 20% margin above the top of the range before flagging "above target", since a little headroom is normal, and reads any average below the bottom of the range as falling short. Overshoot is not a failure, but note it: over-lighting wastes energy and can add glare.

Evenness. The uniformity ratio here, U0 = minimum ÷ average, is the same quantity EN 12464-1 uses to specify indoor lighting, and AS/NZS 1680 works from the same idea: a minimum U0 on a defined task-area grid, commonly U0 ≥ 0.60 for the task area itself (e.g. a desk or workbench) and 0.40 for the immediate surround. Two cautions before you quote a number: the standards prescribe a grid spacing and a task area (roughly square cells, sized to the space), so a comparable U0 needs a reasonably regular grid over the task plane, not a handful of scattered points; and diversity (minimum ÷ maximum) is a different, stricter ratio some guides also quote, so name which one you are reporting.