Commercial Lux Levels and the Essentials of Lighting Design

“How many lux?” is the question every commercial lighting scheme has to answer. But the lux figure is only the headline. Meeting it well is what separates a working scheme from a bright, uncomfortable one.

What lux measures

Lux is the amount of light landing on a surface. In commercial work the target is a maintained illuminance, the level the scheme must still deliver at the end of its maintenance cycle, once lamps have aged and surfaces have gathered dust, not the day it's switched on. Design to the out-of-the-box figure and it's under-lit for most of its life.

Different tasks, different targets

The standard sets illuminance targets by task, not by room. Detailed, precise work needs far more light than a corridor or a store room. In New Zealand these targets come from AS/NZS 1680. General office work, for instance, is commonly designed around 320 lux, while circulation spaces sit well below that and fine, exacting tasks well above. The figure for a given space should always be taken from the current standard for that task, not assumed.

It's not only about the number

Hitting the lux target is necessary but not sufficient. A good scheme also controls uniformity (even light across the task area, not bright patches and shadows), glare (measured as UGR, where too high makes a space tiring to work in), colour rendering (so products, signage and people look right), and maintenance factor (designing in the losses so the space still performs in five years).

Over-lighting is a cost too

More lux isn't better. Over-lighting wastes energy, runs hot, raises glare and costs more to run and replace. The aim is the right light for the task, enough, even, comfortable and efficient, which usually means fewer, better-placed fittings, not more.

Get the calculation done

A proper scheme is calculated, not guessed. Fittings, positions, outputs and maintenance factor are run through a lighting calc against the target. That's what tells you it'll meet the standard on day one and at end of life.

For commercial fit-outs we design to the relevant AS/NZS levels and provide the calcs to prove it. Talk to us before the ceiling's set out.