General Information

Abstract

This document defines a measure for the spectral quality of LED luminaires in terms of the ratio of the amount of visual light emitted by the luminaire versus the amount effective for charging photoluminescent products contained in that spectrum.
Fulfilment of this document by a LED luminaire will ensure general compatibility of the luminaire with photoluminescent marking systems.
This document alone does not provide any means of compliance to fulfil any airworthiness requirements.
For a specific aircraft installation, the spectral power distribution and illuminance at the photoluminescent marking systems are relevant.

Status
Not Published
Public Enquiry End Date
09-Jul-2026
Technical Committee
I13 - Imaginarni 13
Current Stage
4020 - Public enquire (PE) (Adopted Project)
Start Date
21-May-2026
Due Date
08-Oct-2026
Completion Date
10-Jul-2026

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Overview

oSIST prEN 4731:2026 outlines a standardized method for assessing the spectral quality of LED luminaires used with photoluminescent marking systems in the aerospace sector. Developed by SIST as part of the Aerospace Series, this standard defines a critical ratio: the amount of visual light emitted by a luminaire versus the light that is effective at charging photoluminescent products in its spectrum. This quantitative metric, known as the excitation coefficient (Ce), ensures general compatibility between LED luminaires and photoluminescent marking systems commonly found in aircraft cabins.

The focus is on facilitating safety by enabling clear marking visibility in emergencies, where photoluminescent markings provide crucial guidance for evacuation. The standard offers an objective way to evaluate and classify luminaires for their ability to charge these systems, without serving as a direct means of airworthiness compliance.

Key Topics

  • Spectral Quality Definition
    The document introduces the excitation coefficient (Ce) as the measure of how effectively a luminaire charges photoluminescent materials, normalized against emitted visible light.

  • Single vs. Multi-Colour Luminaires
    Clear procedures are provided for determining Ce for both single-colour and multi-colour LED luminaires, supporting a range of design implementations.

  • Measurement and Classification

    • Specifies measurement protocols using spectrometers for the 360 nm–780 nm range.
    • Defines Ce calculation steps for accuracy and repeatability.
    • Establishes four Ce classes (A–D) reflecting charging performance, assisting with product selection and specification.
  • Labelling and Data Reporting
    Luminaire product datasheets must declare the Ce value with three decimal places and, for multi-colour luminaires, the specific colour setting associated with each performance claim.

  • Compatibility Assurance
    Compliance with this standard supports the compatibility of luminaires with photoluminescent safety systems, contributing to cabin safety preparations.

Applications

  • Aircraft Interior Lighting
    The standard is directly applicable to LED luminaires intended for aircraft cabins, where photoluminescent marking systems are required to be self-sufficient for passenger guidance, especially during emergency scenarios.

  • Cabin Safety Systems Design
    Engineers and manufacturers use this standard to select or certify LEDs that maximize photoluminescent charging efficiency, ensuring markings are adequately visible when needed.

  • Specification in Procurement
    Aviation operators and OEMs reference the Ce classification to specify acceptable luminaire performance levels, streamlining procurement and design alignment for safety-critical systems.

  • Interoperability Assessments
    When integrating different luminaires and markings from multiple suppliers, the standardized Ce metric ensures consistent photoluminescent charging, aiding maintenance, retrofits, and upgrades.

Related Standards

  • EN 4706
    Aerospace series – LED colour and brightness ranking – offers guidance for LED classification, which supports procurement and technical assessment alongside oSIST prEN 4731:2026.

  • CIE 018.2:1983
    The basis of physical photometry underpins the photopic luminosity function referenced for spectral weighting.

  • ISO and IEC Terminology
    For additional definitions and harmonized language, the ISO Online Browsing Platform and the IEC Electropedia provide comprehensive databases.


Keywords: LED luminaire, spectral quality, photoluminescent marking systems, aerospace lighting, excitation coefficient, aircraft cabin lighting standard, luminaire Ce classification, emergency marking system compatibility, SIST standard, EN 4731, aviation cabin safety, visual guidance lighting.


This standard provides a robust, harmonized framework for comparing and selecting LED luminaires in aerospace environments where photoluminescent safety markings are used, ensuring reliable safety system performance through precise spectral data and classification.

Relations

Effective Date
11-Mar-2026

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oSIST prEN 4731:2026

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Frequently Asked Questions

oSIST prEN 4731:2026 is a draft published by the Slovenian Institute for Standardization (SIST). Its full title is "Aerospace series - Spectral quality of LED luminaires used with photoluminescent marking systems". This standard covers: This document defines a measure for the spectral quality of LED luminaires in terms of the ratio of the amount of visual light emitted by the luminaire versus the amount effective for charging photoluminescent products contained in that spectrum. Fulfilment of this document by a LED luminaire will ensure general compatibility of the luminaire with photoluminescent marking systems. This document alone does not provide any means of compliance to fulfil any airworthiness requirements. For a specific aircraft installation, the spectral power distribution and illuminance at the photoluminescent marking systems are relevant.

This document defines a measure for the spectral quality of LED luminaires in terms of the ratio of the amount of visual light emitted by the luminaire versus the amount effective for charging photoluminescent products contained in that spectrum. Fulfilment of this document by a LED luminaire will ensure general compatibility of the luminaire with photoluminescent marking systems. This document alone does not provide any means of compliance to fulfil any airworthiness requirements. For a specific aircraft installation, the spectral power distribution and illuminance at the photoluminescent marking systems are relevant.

oSIST prEN 4731:2026 is classified under the following ICS (International Classification for Standards) categories: 29.140.99 - Other standards related to lamps; 49.095 - Passenger and cabin equipment. The ICS classification helps identify the subject area and facilitates finding related standards.

oSIST prEN 4731:2026 has the following relationships with other standards: It is inter standard links to SIST EN 4731:2018. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.

oSIST prEN 4731:2026 is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.

Standards Content (Sample)


SLOVENSKI STANDARD
01-julij-2026
Aeronavtika - Spektralna kakovost LED-svetilk, ki se uporabljajo s
fotoluminiscenčnimi sistemi označevanja
Aerospace series - Spectral quality of LED luminaires used with photoluminescent
marking systems
Luft- und Raumfahrt - Spektrale Qualität von LED-Leuchten zur Verwendung mit
langnachleuchtenden Markierungssystemen
Ta slovenski standard je istoveten z: prEN 4731
ICS:
29.140.99 Drugi standardi v zvezi z Other standards related to
žarnicami lamps
49.095 Oprema za potnike in Passenger and cabin
oprema kabin equipment
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
EUROPEAN STANDARD
NORME EUROPÉENNE
EUROPÄISCHE NORM
April 2026
ICS 49.095; 29.140.99 Will supersede EN 4731:2018
English Version
Aerospace series - Spectral quality of LED luminaires used
with photoluminescent marking systems
Luft- und Raumfahrt - Spektrale Qualität von LED-
Leuchten zur Verwendung mit langnachleuchtenden
Markierungssystemen
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee ASD-
STAN.
If this draft becomes a European Standard, CEN members are bound to comply with the CEN/CENELEC Internal Regulations
which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.

This draft European Standard was established by CEN in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC
Management Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.

Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a European Standard.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2026 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 4731:2026 E
worldwide for CEN national Members.

Contents Page
European foreword . 3
Introduction . 4
1 Scope . 5
2 Normative references . 5
3 Terms, definitions and abbreviations . 5
4 Spectral quality in view of charging photoluminescent products. 7
4.1 Method for determination of Ce for a luminaire . 7
4.1.1 Single colour LED luminaires . 7
4.1.2 Multiple colour LED luminaires . 8
4.1.3 Examples of different light spectra. 8
4.2 Requirement . 8
4.2.1 Ce classification . 8
4.2.2 Labelling . 9
Annex A (informative) Approximated excitation spectrum . 10
Annex B (informative) Examples of different light spectra . 11
Bibliography. 16

European foreword
This document (prEN 4731:2026) has been prepared by ASD-STAN.
After enquiries and votes carried out in accordance with the rules of this Association, this document has
received the approval of the National Associations and the Official Services of the member countries of
ASD-STAN, prior to its presentation to CEN.
This document is currently submitted to the CEN Enquiry.
This document will supersede EN 4731:2018.
— new term “colour setting” and using it instead of “colour mode”;
— correct the definition of term “photopic luminosity function”;
— change heading of Clause 4 into “Spectral quality in view of charging photoluminescent products”.
Introduction
Photoluminescent marking systems are commonly used in passenger airplanes to provide visual
guidance in emergency events. Those marking systems need to be charged by ambient light during
cabin preparation and/ or aircraft operation as to be operational if, at any phase of a flight, an
emergency occurs.
While the certification regulations require photoluminescent marking system to be sufficiently charged
solely by cabin interior lighting, i.e. without accounting for daylight entering the cabin through
windows, only certain portions of the visual light spectrum emitted by a cabin interior luminaire are
stored by the photoluminescent pigment and thus contribute to charging.
1 Scope
This document defines a measure for the spectral quality of LED luminaires in terms of the ratio of the
amount of visual light emitted by the luminaire versus the amount effective for charging
photoluminescent products contained in that spectrum.
Fulfilment of this document by a LED luminaire will ensure general compatibility of the luminaire with
photoluminescent marking systems.
This document alone does not provide any means of compliance to fulfil any airworthiness
requirements.
For a specific aircraft installation, the spectral power distribution and illuminance at the
photoluminescent marking systems are relevant.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
EN 4706, Aerospace series — LED colour and brightness ranking
3 Terms, definitions and abbreviations
For the purposes of this document, the following terms, definitions and abbreviations apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https://www.iso.org/obp
— IEC Electropedia: available at https://www.electropedia.org/
3.1
Light Emitting Diode
LED
solid state device embodying a p-n junction, emitting optical radiation when excited by an electric
current
3.2
single colour LED luminaire
luminaire using one or more LEDs as source of light whereas the luminaire is designed to operate in a
single colour setting only
3.3
multiple colour LED luminaire
luminaire using two or more LEDs as source of light whereas the LEDs are of at least two different
primary wavelengths and the luminaire is designed to operate in two or more colour settings
3.4
colour setting
set of parameters that define the power setting of every primary of a multiple colour LED Luminaire
thus achieving a specific colour output
3.5
spectral irradiance
Eλ(λ)
function that relates the spectral irradiance E𝜆𝜆 of a light source to the wavelength λ
Note 1 to entry: The function’s unit is W/m /nm.
3.6
photopic luminosity function
V(λ)
function that relates the average spectral sensitivity of human visual perception of brightness for
photopic vision to the wavelength 𝜆𝜆
Note 1 to entry: Published by the Commission Internationale de L’Éclairage (CIE) in steps of one nanometer with
document CIE 018.2:1983.
3.7
photom
...