kSIST FprEN IEC 63544:2026

• Status: Not Published
• Public Enquiry End Date: 04-Mar-2026
• ICS: 29.140.40 - Luminaires
• ICS: 65.060.70 - Horticultural equipment
• Technical Committee: STV - Steklo, svetloba in razsvetljava v gradbeništvu
• Current Stage: 5020 - Formal vote (FV) (Adopted Project)
• Start Date: 29-Sep-2026
• Due Date: 17-Nov-2026
• Completion Date: 30-Oct-2026
• Ref Project: FprEN IEC 63544:2026 - Horticultural lighting - Luminaires incorporating LED light sources for horticultural lighting - Performance

kSIST FprEN IEC 63544:2026 is a SIST standard for horticultural lighting based on IEC work on luminaires incorporating LED sources. It specifies performance requirements, measurement methods and test conditions for horticultural luminaires, so manufacturers, test laboratories, specifiers and buyers can describe and check product performance in the same technical terms. The document focuses on type testing, photon-based performance data and how that data should be declared and verified.

What does kSIST FprEN IEC 63544:2026 specify?

kSIST FprEN IEC 63544:2026 specifies the performance requirements for horticultural luminaires incorporating LED sources, together with the measurement methods and conditions used to check them. It is written for type testing, not for verifying a manufacturer’s lifetime claim, and it leaves action spectra outside its scope because those depend on plant species and growth stage.

The document is organized into clauses on general requirements, product classification, product information, test conditions, input power, radiometric performance, maintenance characteristics, dimensions and construction, thermal radiation effect and verification. It also has two informative annexes that give background guidance rather than binding requirements.

Annex	What it covers
Annex A	Information on thermal radiation from horticultural luminaires to plants, including examples of threshold temperatures and heat-killing temperatures
Annex B	Construction recommendations for horticultural luminaires incorporating LED sources

What are the key requirements of kSIST FprEN IEC 63544:2026?

kSIST FprEN IEC 63544:2026 sets the performance framework around photon-based quantities instead of the photometric quantities used for general lighting. In practice, that means the declared and measured values have to match horticultural use, where plant response is tied to wavelength ranges and long-term maintenance matters.

General requirements and product family

Clause 4 requires horticultural luminaires incorporating LED sources to comply with IEC 62722-1, except where this document gives alternative methods or limits. It also excludes colorimetric requirements and says the family-identification criteria from IEC 62722-2-1 apply. For replaceable LED sources, testing is done on the luminaire with the declared source combination, so the performance claim has to match the exact product configuration.

Product classification

Clause 5 classifies horticultural luminaires by the wavelength range they mainly emit. The two classes are products primarily emitting photosynthetically active radiation and products primarily emitting UV radiation. This matters because the declared data, the test emphasis and the product information depend on which spectral region is the main purpose of the luminaire.

Product information to declare

Clause 6 requires the manufacturer or responsible vendor to provide a defined set of product information in datasheets, leaflets or on a website, and some of it also has to appear on the package. The declared data include rated photon flux, initial photon flux in key bands, photon flux efficacy, photon intensity distribution, spectral distribution of photon quantity, photon irradiance at typical installation height, rated operation time to 90% maintenance factor, ambient performance temperature, dimming characteristics, operating instructions, application scenarios, dimensions, weight and maintenance instructions. For a buyer or designer, this is the information used to compare products and plan installation conditions.

Test conditions and test matrix

Clause 7 adapts the general LED luminaire test conditions to horticultural use. The measured wavelength range is normally 280 nm to 800 nm, but if the product is designed for a specific wavelength range, only that range is measured. The clause also requires the ambient temperature and relative humidity used for maintenance testing to be reported, and it gives 35 °C and 90% RH as the default when the manufacturer does not specify conditions.

Table 2 is important because it splits the testing duties between horticultural luminaires of type A and type B. Type A luminaires can use certified LED module performance data in some cases, while type B luminaires and luminaires with replaceable LED sources have a broader set of required tests. If a product uses multiple LED modules or adds secondary optics, more of the luminaire has to be measured directly.

Performance checks

Clauses 8 and 9 define the core performance checks. Initial photon flux and initial photon flux efficacy have to reach at least 90% of the rated values, which gives a clear acceptance rule for declared output. The initial photon intensity distribution has to match the manufacturer’s declaration, the spectral distribution of photon quantity has to be declared with wavelength intervals no larger than 5 nm, and photon irradiance at the typical installation height has to stay within 20% of the declared value. In practice, this is the section that confirms whether the lamp delivers the light quantity, direction and spectrum that the user expects.

Maintenance, dimensions and verification

Clause 10 covers maintenance of photon flux over time. If a rated operation time to 90% maintenance factor is stated, the photon flux at that time must not fall below 90% of the initial value, and the document allows calculated values based on IEC 63013 reports for the applicable LED packages. Clause 11 requires the installation-related dimensions to match the manufacturer’s specifications, and clause 13 says the test sample must represent production, with LED manufacturer data usable only when the luminaire design does not change the optical or thermal behavior of the LED packages or modules. For systems with external controlgear, its input power must be included when full-system efficiency is measured.

What terms does kSIST FprEN IEC 63544:2026 define?

• LED source - A source of optical radiation based on LED technology, including an LED module or an LED lamp.
• photobiologically active radiation (PBAR) - Optical radiation from 280 nm to 800 nm that is active for plants.
• photosynthetically active radiation (PAR) - Optical radiation from 400 nm to 700 nm, commonly divided into blue, green and red bands.
• photon flux - The rate of photon number per unit time, used here as a core output quantity.
• photon flux efficacy - Emitted photon flux divided by electrical input power, expressed for horticultural lighting in micromole per joule.
• photon irradiance - The density of incident photon flux per unit area at a surface.
• maintenance factor - The quotient of a maintained value after a time interval and the initial value.

Who uses kSIST FprEN IEC 63544:2026?

kSIST FprEN IEC 63544:2026 is used by luminaire manufacturers, LED module suppliers and responsible vendors when they declare horticultural lighting performance data. It is also used by test laboratories, certification bodies, quality managers, engineering designers and procurement teams that need to verify ratings, compare products or check whether a luminaire is suitable for a greenhouse, plant factory, indoor farm, field application or home application.

It is especially relevant where installation height, spectral control, dimming, maintenance performance and thermal effects on plants need to be documented rather than assumed.

What changed in kSIST FprEN IEC 63544:2026 from the previous edition?

kSIST FprEN IEC 63544:2026 is identical with prEN IEC 63544:2025.

Which standards are used with kSIST FprEN IEC 63544:2026?

• IEC 60068-2-78 - Provides the damp heat, steady-state environmental test method used in the normative references.
• IEC 62722-1 - Supplies the general luminaire performance framework that this document builds on, with horticultural-specific exceptions.
• IEC 62722-2-1:2023 - Provides the LED luminaire performance basis that is adapted here for horticultural use.
• IEC 63545 - Gives the safety requirements that horticultural luminaires must also meet.

What does the kSIST FprEN IEC 63544:2026 document contain?

kSIST FprEN IEC 63544:2026 contains a product information table, a test-condition section, and a performance table that shows which measurements are required for type A and type B luminaires. It also contains the main radiometric checks for photon flux, photon flux efficacy, photon intensity distribution, spectral distribution and photon irradiance.

The informative annexes add practical guidance that helps with design and installation. Annex A collects thermal-radiation information for plant protection and installation planning, while Annex B gives construction recommendations such as cleanable surfaces and avoidance of dust-collecting features. The document also points readers to IEC 62722-1 for the method used to check photon intensity distribution and to IEC 63013 reports when maintenance values are calculated.

SLOVENSKI STANDARD
oSIST prEN IEC 63544:2026
01-marec-2026
Vrtnarska razsvetljava - Svetila z vgrajenimi LED viri za vrtnarsko razsvetljavo -
Zmogljivost
Horticultural lighting - Luminaires incorporating LED sources for horticultural lighting -
Performance
Ta slovenski standard je istoveten z: prEN IEC 63544:2025
ICS:
29.140.40 Svetila Luminaires
65.060.70 Vrtnarska oprema Horticultural equipment
oSIST prEN IEC 63544:2026 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

oSIST prEN IEC 63544:2026
oSIST prEN IEC 63544:2026
34/1405/CDV
COMMITTEE DRAFT FOR VOTE (CDV)
PROJECT NUMBER:
IEC 63544 ED1
DATE OF CIRCULATION: CLOSING DATE FOR VOTING:
2025-12-12 2026-03-06
SUPERSEDES DOCUMENTS:
34/1310/CD, 34/1341A/CC
IEC TC 34 : LIGHTING
SECRETARIAT: SECRETARY:
United Kingdom Mr Petar Luzajic
OF INTEREST TO THE FOLLOWING COMMITTEES: HORIZONTAL FUNCTION(S):
SC 34D
ASPECTS CONCERNED:
SUBMITTED FOR CENELEC PARALLEL VOTING NOT SUBMITTED FOR CENELEC PARALLEL VOTING
– Attention IEC-CENELEC parallel voting
– The attention of IEC National Committees,
members of CENELEC, is drawn to the fact that this
Committee Draft for Vote (CDV) is submitted for parallel
voting.
– The CENELEC members are invited to vote through
the CENELEC online voting system.

– This document is still under study and subject to change. It should not be used for reference purposes.
– Recipients of this document are invited to submit, with their comments, notification of any relevant patent rights of
which they are aware and to provide supporting documentation.
– Recipients of this document are invited to submit, with their comments, notification of any relevant “In Some
Countries” clauses to be included should this proposal proceed. Recipients are reminded that the CDV stage is the final
stage for submitting ISC clauses. (SEE AC/22/2007 OR NEW GUIDANCE DOC).

TITLE:
Horticultural lighting – Luminaires incorporating LED sources for horticultural lighting -
Performance
PROPOSED STABILITY DATE: 2029
NOTE FROM TC/SC OFFICERS:
this electronic file, to make a copy and to print out the content for the sole purpose of preparing National Committee
positions. You may not copy or "mirror" the file or printed version of the document, o r any part of it, for any other purpose
without permission in writing from IEC.

oSIST prEN IEC 63544:2026
IEC CDV 63544 © IEC 2025
1 CONTENTS
4 CONTENTS . 1
5 FOREWORD . 2
6 INTRODUCTION . 4
7 1 Scope . 5
8 2 Normative references . 5
9 3 Terms and definitions . 5
10 4 General requirements . 10
11 5 Product classification . 10
12 6 Product information . 10
13 7 Test conditions . 11
14 8 Input power . 12
15 9 Radiometric performance . 12
16 9.1 Photon flux . 12
17 9.2 Photon flux efficacy . 12
18 9.3 Photon intensity distribution . 12
19 9.4 Spectral distribution of photon quantity. 12
20 9.5 Photon irradiance . 12
21 10 Maintenance characteristics of photon flux . 13
22 11 Dimensions and construction . 13
23 11.1 Dimensions . 13
24 11.2 Construction . 13
25 12 Thermal radiation effect . 13
26 13 Verification . 13
27 Annex A (informative) Information on thermal radiation from the horticultural
28 luminaires to the plants . 15
29 Annex B (informative) Construction recommendations . 17
30 Bibliography . 18
oSIST prEN IEC 63544:2026
IEC CDV 63544 © IEC 2025
36 INTERNATIONAL ELECTROTECHNICAL COMMISSION
37 ____________
39 Horticultural lighting – Luminaires incorporating LED sources for
40 horticultural lighting – Performance
43 FOREWORD
44 1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
45 all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
46 international co-operation on all questions concerning standardization in the electrical and electronic fields. To
47 this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
48 Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
49 Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
50 in the subject dealt with may participate in this preparatory work. International, governmental and non -
51 governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
52 with the International Organization for Standardization (ISO) in accordance with conditions determined by
53 agreement between the two organizations.
54 2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
55 consensus of opinion on the relevant subjects since each technical committee has representation from all
56 interested IEC National Committees.
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59 Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
60 misinterpretation by any end user.
61 4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
62 transparently to the maximum extent possible in their national and regional publications. Any divergence
63 between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
64 the latter.
65 5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
66 assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
67 services carried out by independent certification bodies.
68 6) All users should ensure that they have the latest edition of this publication.
69 7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
70 members of its technical committees and IEC National Committees for any personal injury, property damage or
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72 expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
73 Publications.
74 8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
75 indispensable for the correct application of this publication.
76 9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
77 patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
78 IEC 6XXXX has been prepared by IEC technical committee 34: Lighting. It is an International
79 Standard.
80 The text of this International Standard is based on the following documents:
Draft Report on voting
34/XX/FDIS 34/XX/RVD
oSIST prEN IEC 63544:2026
IEC CDV 63544 © IEC 2025
82 Full information on the voting for its approval can be found in the report on voting indicated in
83 the above table.
84 The language used for the development of this International Standard is English.
85 This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
86 accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
87 at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
88 described in greater detail at www.iec.ch/publications.
89 The committee has decided that the contents of this document will remain unchanged until the
90 stability date indicated on the IEC website under webstore.iec.ch in the data related to the
91 specific document. At this date, the document will be
92 reconfirmed,
93 withdrawn,
94 replaced by a revised edition, or
95 amended.
oSIST prEN IEC 63544:2026
IEC CDV 63544 © IEC 2025
97 INTRODUCTION
98 This document acknowledges the need for defining performance data to be provided for
99 horticultural luminaires using LED as the electric source. Information to support the responsible
100 horticultural lighting environmental use is also included.
101 Compared with general lighting, the major differences for horticultural lighting are as follows:
102 Changing of performance metric system from photometric to photon system, which is
103 normally based on specific wavelength range;
104 Increased concern for the endurance properties because of the close relevance to the
105 crop yield.
106 The provisions in this document represent the technical knowledge of experts from the field of
107 the horticultural lighting, and are developed in close context with IEC 62722-1 (the performance
108 standard for luminaires in general) and IEC 62722-2-1 (the performance standard for LED
109 luminaires for general lighting purpose).
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113 Horticultural lighting – Luminaires incorporating LED sources for
114 horticultural lighting – Performance
117 1 Scope
118 This document specifies the performance requirements together with the measurement method
119 and conditions for horticultural luminaires incorporating LED sources.
120 The requirements of this document relate to type testing.
121 The lifetime of horticultural luminaires incorporating LED sources is in most cases much longer
122 than practical test times. Consequently, the verification of manufacturer’s lifetime claim is out
123 of the scope of this document.
124 This document does not contain requirements on action spectra, which are dependent on plant
125 species and growth stages.
126 2 Normative references
127 The following documents are referred to in the text in such a way that some or all of their content
128 constitutes requirements of this document. For dated references, only the edition cited applies.
129 For undated references, the latest edition of the referenced document (including any
130 amendments) applies.
131 IEC 60068-2-78, Environmental testing - Part 2-78: Tests - Test Cab: Damp heat, steady state
132 IEC 62722-1, Luminaire performance – Part 1: General requirements
133 IEC 62722-2-1:2023, Luminaire performance – Part 2-1: Particular requirements for LED
134 luminaires
135 IEC 63545, Horticultural lighting – luminaires for horticultural lighting – Safety
136 3 Terms and definitions
137 For the purposes of this document, the terms and definitions given in IEC 62722-2-1, IEC 63545
138 and the following apply.
139 ISO and IEC maintain terminology databases for use in standardization at the following
140 addresses:
141 IEC Electropedia: available at https://www.electropedia.org/
142 ISO Online browsing platform: available at https://www.iso.org/obp
143 3.1
144 LED source
145 source of optical radiation based on LED technology
146 Note 1 to entry: An LED source can take the form of an LED module or an LED lamp.
oSIST prEN IEC 63544:2026
IEC CDV 63544 © IEC 2025
147 Note 2 to entry: LED source can be the source emitting optical radiation other than visual radiation.
148 3.2
149 photobiologically active radiation
150 PBAR
151 optical radiation in the wavelength range from 280 nm to 800 nm for which plants are
152 photobiologically active
153 Note 1 to entry: Quantities that are related to PBAR should be labelled using the subscript “PBAR”.
154 3.3
155 photosynthetically active radiation
156 PAR
157 optical radiation in the wavelength range from 400 nm to 700 nm
158 Note 1 to entry: The range between 400 nm to 700 nm for horticultural lighting is commonly subdivided into:
159 blue: 400 nm to 500 nm;
160 green: 500 nm to 600 nm;
161 red: 600 nm to 700 nm.
162 Note 2 to entry: Quantities that are related to photosynthetically active radiation should be labelled using the
163 subscript “PAR”.
164 3.4
165 far-red radiation
166 optical radiation in the wavelength range from 700 nm to 800 nm
167 3.5
168 photon flux
169 Fp
170 F
171 rate of photon number per time interval
𝒅𝑵
𝐩
172 𝛷 =
𝐩
𝒅𝒕
173 where 𝑁 is photon number, transmitted or received, and t is time.
p
𝛷
e
174 Note 1 to entry: Photon flux, 𝛷 , is related to radiant flux, 𝛷 , of monochromatic radiation by 𝛷 = ,where ℎ is the Planck
p e p
ℎ𝜈
175 constant, and 𝜈 is the frequency of the corresponding electromagnetic wave.
d𝛷 (λ) d𝛷 (λ)
e e
176 Note 2 to entry: For a beam of radiation whose spectral distribution is or , the photon flux can be expressed by 𝛷 =
p
𝑑λ 𝑑𝜈
λ 𝛷 (λ) λ λ 𝛷 (v) λ
𝟐 e 𝟐 e
177 ∙ 𝑑λ = ∙ 𝑑𝜈, where ℎ is Planck's constant, 𝑐 is the speed of light in vacuum.
∫ ∫
λ 𝑑λ ℎ𝑐 λ 𝑑ν ℎ𝜈
𝟏 𝟏
178 Note 3 to entry: The corresponding radiometric quantity is "radiant flux". The corresponding photometric quantity is "luminous
179 flux".
−1
180 Note 4 to entry: The photon flux is expressed in second to the power minus one (s ).
-
181 Note 5 to entry: Unit for photon flux for horticultural lighting purpose is normally expressed as micromoles per second (μmol × s
1 23 6
182 ). The quantity is calculated by dividing ᶲ by Avogadro’s number N (6.022 × 10 photons per mole) and then multiply by 10 .
p A
oSIST prEN IEC 63544:2026
IEC CDV 63544 © IEC 2025
183 Note 6 to entry: Photon flux is normally associated with specific wavelength ranges. Examples are photosynthetic photon flux,
184 ultraviolet photon flux, far-red photon flux.
185 [SOURCE: IEC 60050-845:2020, 845-21-040 modified – The note 5 to entry and note 6 to
186 entry have been added.]
187 3.6
188 photobiologically active photon flux
189 photon flux in the wavelength range from 280 nm to 800 nm for which plants are photobiologically
190 active
191 3.7
192 photon flux efficacy
193 𝜂
p
194 emitted photon flux divided by the electrical input power
𝛷
p
195 𝜂 =
p
𝑃
196 where 𝛷 is photon flux and P is the electrical input power
p
197 Note 1 to entry: Whether the input power includes power dissipated by auxiliary equipment such as controlgear should be
198 specified.
−1
199 Note 2 to entry: Photon flux efficacy for horticultural lighting is expressed in micromole per Joule ( μmol·J ).
200 Note 3 to entry: Photon flux efficacy is normally associated with specific wavelength ranges. Examples are
201 photosynthetic photon flux efficacy, ultraviolet photon flux efficacy, far-red photon flux efficacy.
202 3.8
203 photon intensity
204 I ;
p
205 I
206 density of photon flux with respect to solid angle in a specified direction
𝑑𝛷
p
207 𝐼 =
p
𝑑Ω
208 where Φp is the photon flux emitted in the given direction, and Ω is the solid angle containing that
209 direction
210 Note 1 to entry: The distribution of the photon intensities as a function of the direction of emission, e.g. given by the polar angles
211 (θ, Φ), is used to determine the photon flux, Φp, within a certain solid angle, Ω, of a source:
( )
212 𝛷 = ∬ 𝐼 𝜃, 𝜑 sin 𝜃 𝑑𝜑𝑑𝜃
P P
Ω
213 Note 2 to entry: The corresponding radiometric quantity is "radiant intensity". The corresponding photometric quantity is
214 "luminous intensity".
215 Note 3 to entry: The photon intensity is expressed in second to the power minus one times steradian to the power minus one
−1 −1
216 (s ·sr ).
217 Note 4 to entry: Photon intensity is normally associated with specific wavelength ranges. Examples are photosynthetic photon
218 intensity, ultraviolet photon intensity, far-red photon intensity.
219 [SOURCE: IEC 60050-845:2020, 845-21-046 modified – The note 4 to entry has been added.]
220 3.9
221 photon intensity distribution
oSIST prEN IEC 63544:2026
IEC CDV 63544 © IEC 2025
222 photon intensity of a source as a function of direction in space
223 3.10
224 photon irradiance
225 photon flux density
226 E
p
227 E
228 density of incident photon flux with respect to area at a point on a real or imaginary surface
𝑑𝛷
p
229 𝐸 =
p
𝑑𝐴
230 where 𝛷 is photon flux and 𝐴 is the area on which the photon flux is incident
p
231 Note 1 to entry:  The corresponding radiometric quantity is "irradiance". The corresponding photometric quantity is
232 "illuminance".
−1 −2
233 Note 2 to entry:  The photon irradiance is expressed in second to the power minus one per square metre (s ∙ m ).
234 Note 3 to entry: Unit for photon irradiance for horticultural lighting purpose is normally expressed as micromoles per second per
-1 -2 23
235 square meter (μmol × s × m ). The quantity is calculated by dividing E by Avogadro’s number N (6.022 × 10 photons per
p A
236 mole) and then multiply by 10 .
237 Note 4 to entry: Photon irradiance is normally associated with specific wavelength ranges. Examples are photosynthetic photon
238 irradiance, ultraviolet photon irradiance, far-red photon irradiance.
239 [SOURCE: IEC 60050-845:2020, 845-21-058, modified – The alternative term name, the note
240 3 to entry and note 4 to entry have been added.]
241 3.11
242 spectral distribution
243 spectral concen
...