How to read a luminaire specification: lm/W, IP, Ra

A luminaire specification is a dozen lines long, and almost every one of them can be verified. Below are the lines that most often decide a purchase.

Luminous efficacy: what the lot actually asks for

The first line worth checking in your own specification is luminous efficacy. The usual wording is “not less than 100 lm/W”. It screens out the cheapest imports without excluding a single serious supplier. We went through 4,445 conditions found in lots for luminaires: 592 of them ask for luminous efficacy, and half of those ask for 100 lm/W or more.

Then the subtlety begins. Luminous efficacy can be declared from the data sheet of the LED modules, or measured on the assembled luminaire. These are different numbers: in the assembly, flux is lost in the diffuser, in the optics and to heat. The correct wording reads: “luminous efficacy of N lm/W is confirmed by an ANSI/IES LM-79 measurement report, laboratory X, measured on the assembled product at Ta = 25 °C”. If an offer carries only a number and no report, you are comparing promises rather than luminaires.

We address that requirement to ourselves as well. We do not have an LM-79 report on the assembled luminaire yet: the model cards carry a calculated “up to 180 lm/W” from the module data sheet, and next to it the flux and efficacy from the attached IES file, 130-140 lm/W. Until the report exists, compare us by the IES files: they sit on the downloads page and need no form.

Service life is a separate source of confusion. The LM-80 report is issued by the LED manufacturer, not by the company assembling the luminaire. The L70 figure is not measured, it is projected to IES TM-21 from that report. A supplier presenting “our own LM-80” is either confusing the terms or counting on the committee not to notice.

IP: where the protection rating really matters

IP54 covers dust and splashes, which is enough for a production hall, a warehouse or an indoor sports facility. IP65 is needed where water arrives as a jet and dust storms reach: streets, plant grounds, fuel stations, car parks with open entries. Writing IP65 into a specification for an office luminaire adds cost and nothing else.

Ra and colour temperature

The colour rendering index Ra is set as a minimum value, and it matters where decisions are made by colour: quality control on a production line, a retail floor, a televised sports event. Colour temperature should be chosen in the specification rather than left to the supplier: production usually takes neutral light, streets go cooler, public interiors warmer. Our series are produced in several colour temperatures, and the chosen one is fixed in the bill of materials.

What is asked for beyond the parameters

A luminaire goes through mandatory conformity assessment: a declaration of conformity under clause 107 of annex 4 to Cabinet of Ministers Resolution No. 43 of 30 January 2021, supported by test reports to GOST IEC 60598-1-2017 and related standards. That is not marketing, it is market access.

Within the bid itself, price is not the heaviest item. We looked at 50 active lots on 7 September 2026: the winner was chosen by the scoring method in 33 cases, and in 24 of those the technical part weighed 70 % against 30 % for price. Form 7, the table comparing parameters against the specification, and the 36-month warranty letter do not work as points at all: a mismatch or an omission means disqualification from the procedure.

How to read all this

A requirement in a specification means something only when it says what confirms it. Ask for a document rather than a number: a test report, a declaration, a data sheet, an IES file. Comparing offers then stops being an argument about advertising and becomes a check.