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How to use it
Enter the room's dimensions and height, the work plane height and the colour of the surfaces. Choose the activity or type the required illuminance, then the flux and power of the luminaire you want to use. The tool calculates the number of luminaires, arranges them on a regular grid and returns the maintained average illuminance and installed power.
Lumen method
The utilisation factor UF says how much of the emitted flux reaches the work plane: it increases with the room index and with the reflectance of ceiling, walls and floor. If you don't enter a value, the tool uses a typical estimate for direct-emission LED luminaires. The maintenance factor MF accounts for the drop in flux over time and dirt: 0.8 is a common value for clean environments with LEDs.
The illuminance values offered are typical references; those required for each visual task are in EN 12464-1, together with the requirements for uniformity, glare (UGR) and colour rendering.
From calculation to design
The lumen method gives the number of luminaires, not the quality of the light. A complete lighting design uses the luminaire's real photometry for a point-by-point calculation, checks uniformity and glare and compares installation and running costs. In energy upgrades of installations we combine it with measured savings and the payback time of the investment.
FAQ
How many lux does a machine shop need?
As a reference: 300 lx for rough work, 500 lx for machining and assembly, 750 lx or more for fine assembly and precision inspection. The values required for each task are in EN 12464-1.
What maintenance factor should I use?
For LEDs in clean environments with regular maintenance 0.8 is often used; in dusty environments or with infrequent cleaning it drops to 0.6–0.7.
Where do I find the real utilisation factor?
In the luminaire's photometric documentation, often as a table depending on the room index and reflectances, or with lighting software that uses the photometric file.
How far apart should the luminaires be?
As a rule the spacing shouldn't exceed 1–1.5 times the working height, depending on the optics: beyond that, illuminance between one luminaire and the next drops too much and uniformity worsens.