How To Read An IES File And A Dialux Report

What An IES File Is

An IES file is the measured light distribution of one fixture, published in a standard format. It records how much light leaves the fitting in every direction. Without it, no designer can model your fixture, and any layout they produce is guesswork. We supply IES files for our fixtures on request.

What The Polar Curve Tells You

The polar plot in an IES viewer shows intensity against angle. A tall narrow curve is an accent fitting; a broad flat curve is a wash. Comparing the curve against the claimed beam angle is the quickest way to check whether a fitting really does what the datasheet says.

What A Dialux Report Should Contain

At minimum: the room geometry and reflectances used, the fixture and its IES source, a false-colour or isoline plot, average illuminance at the working plane, and uniformity. If a report gives you an average lux number with none of that context, it cannot be checked.

Uniformity Matters As Much As Average Lux

An average of 500 lux made up of bright pools and dark gaps reads worse than an even 400 lux. Look at the uniformity figure and the isoline plot together, and be suspicious of a layout that hits its target only directly under the fittings.

Use It Before The Order, Not After

The point of the calculation is to settle fixture count, beam angle and spacing while they are still free to change. Send us the reflected ceiling plan with ceiling heights and the target level, and we will run the calculation and return the fixture schedule.