oSIST prEN 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
• Ref Project: FprEN IEC 63544:2026 - Horticultural lighting - Luminaires incorporating LED light sources for horticultural lighting - Performance

oSIST prEN IEC 63544:2026 is the Slovenian standard identical to prEN IEC 63544:2025, published by SIST for horticultural lighting. It specifies performance requirements, measurement methods and test conditions for luminaires incorporating LED sources used in horticultural lighting, so manufacturers, responsible vendors, test laboratories and designers can describe and verify how these products perform in practice.

What does oSIST prEN IEC 63544:2026 specify?

oSIST prEN IEC 63544:2026 covers the performance of horticultural luminaires incorporating LED sources. It focuses on type testing, defines the measured photon-based quantities used for horticultural lighting, and sets the product information that the manufacturer or responsible vendor has to publish.

The document is organized into 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 on plant heating and construction practice.

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

What are the key requirements of oSIST prEN IEC 63544:2026?

The most important point in oSIST prEN IEC 63544:2026 is that horticultural lighting is treated with photon metrics, not the usual photometric quantities used for general lighting. That matters because the document is written for plant growth applications, where wavelength range and photon output are more relevant than human visual response.

General performance basis

Clause 4 says horticultural luminaires incorporating LED sources shall comply with IEC 62722-1, with two important exceptions:

• alternative measurement methods or limits in this document take priority
• colorimetric data are excluded

In practice, this means users should not apply general-lighting color requirements here, and should follow the horticultural-specific photon-based methods whenever the document gives them.

Clause 4 also says the family identification criteria of IEC 62722-2-1 apply, and the luminaire shall comply with IEC 63545 for safety. For replaceable LED sources, the test is carried out on the luminaire with the LED source or sources used for the declared performance.

Product classification and product information

Clause 5 classifies horticultural luminaires by emitted wavelength range:

• products primarily emitting photosynthetically active radiation, which may also include UV and far-red radiation
• products primarily emitting UV radiation

Clause 6 requires the manufacturer or responsible vendor to provide product information in datasheets, leaflets or on the website. The table in Clause 6 asks for declared values such as rated photon flux, photon flux efficacy, photon intensity distribution, spectral distribution of photon quantity, photon irradiance under typical installation height, operation time to 90% maintenance factor, ambient performance temperature, dimming characteristics, configuration instructions, applicable scenarios, dimensions, weight, installation instructions, and use and maintenance guidance.

In practice, this is the information buyers, engineers and installers need to compare products and set up the luminaire correctly.

Test conditions and test matrix

Clause 7 adapts the test conditions from IEC 62722-2-1:2023. Colorimetric test conditions do not apply, photometric terms are to be read as photon-metric terms, and the full measured wavelength range is 280 nm to 800 nm unless the luminaire is designed for a narrower specified range. For maintenance testing, the ambient temperature and relative humidity have to be reported, and if the manufacturer, responsible vendor and engineering designer do not specify them, 35 °C and 90% RH are used.

Clause 7 also sets the test matrix for horticultural luminaires of type A and type B.

Test or requirement	Type A	Type B	Practical meaning
LED module performance temperature	required	required	The source operating temperature must be checked
Input power	required	required	Electrical consumption has to be measured
Photon flux	required	required	Initial light output for plants has to be verified
Photon flux efficacy	required	required	Output per watt has to be verified
Photon intensity distribution	required	required	Directional output has to match the declaration
Spectral distribution of photon quantity	required	required	The wavelength profile has to be checked
Photon irradiance under typical installation height	required	required	The delivered light at installation distance has to be verified
Maintenance characteristics of photon flux	not required	required	Long-term photon maintenance is checked for type B
Endurance tests	not required	required	Long-term operation is checked for type B
Dimensions and construction	required	required	Physical design and installation fit are checked
Thermal radiation effect	required	required	Heating impact on plants is considered

Type A uses LED modules with declared compliance to the corresponding IEC performance standard, and certified module data from IEC 63555 can be used without retesting the whole luminaire in some cases. Type B covers LED modules without that compliance, or luminaires with replaceable LED sources.

Performance limits

Clause 9 gives the main acceptance criteria for initial performance:

• measured initial photon flux shall be at least 90% of the rated photon flux
• measured initial photon flux efficacy shall be at least 90% of the rated photon flux efficacy
• initial photon intensity distribution shall match the manufacturer’s declaration
• initial spectral distribution of photon quantity shall be declared with wavelength interval resolution not larger than 5 nm
• photon irradiance at the typical installation height shall not deviate from the declared value by more than 20%

In practice, this means the declared numbers on the datasheet are not just descriptive - they are the values against which the product is checked.

Maintenance, dimensions and construction

Clause 10 covers maintenance characteristics of photon flux. Where a rated operation time to 90% maintenance factor is declared, the photobiologically active photon flux at that time shall not be lower than 90% of the initial value. Clause 10 also asks for maintained photon flux to be reported for blue, green, red and far-red ranges, and maintained UV radiant flux if applicable.

Clause 11 requires the installation-related dimensions to comply with the manufacturer’s specification and says construction recommendations are given in Annex B. Clause 12 explains that thermal radiation from the luminaire can affect plant growth and points readers to Annex A. Clause 13 says type test samples shall represent production, and LED manufacturer data may be used for verification when the luminaire design does not alter optical or thermal characteristics.

What terms does oSIST prEN IEC 63544:2026 define?

• LED source - A source of optical radiation based on LED technology; it may be an LED module or an LED lamp.
• photobiologically active radiation (PBAR) - Optical radiation from 280 nm to 800 nm for which plants are photobiologically active.
• photosynthetically active radiation (PAR) - Optical radiation from 400 nm to 700 nm, commonly split into blue, green and red ranges.
• photon flux - The rate of photon number per time interval, expressed for horticultural lighting in units such as μmol/s.
• photon flux efficacy - Emitted photon flux divided by electrical input power, usually expressed in μmol/J.
• photon irradiance - The density of incident photon flux on a surface, usually expressed in μmol/s/m².
• maintenance factor - The quotient of a maintained value after a time interval and the initial value.
• rated value - A declared specification value established under standard test conditions.

Who uses oSIST prEN IEC 63544:2026?

oSIST prEN IEC 63544:2026 is used by manufacturers and responsible vendors of horticultural luminaires incorporating LED sources when they prepare product datasheets, websites and installation instructions. It is also used by test laboratories and engineering teams that carry out type testing, measure photon output and confirm maintenance characteristics.

The document is relevant to horticultural lighting applications such as plant factories, greenhouses, field applications and home applications, including inter-plant supplementary lighting and top lighting. Quality managers, buyers and conformity assessment bodies can use it to compare declared performance with measured performance in a consistent way.

What changed in oSIST prEN IEC 63544:2026 from the previous edition?

The document shown is a Committee Draft for Vote and it supersedes 34/1310/CD and 34/1341A/CC.

Which standards are used with oSIST prEN IEC 63544:2026?

• IEC 60068-2-78 - Gives the damp heat, steady-state environmental test used in the normative references.
• IEC 62722-1 - Provides the general luminaire performance requirements that Clause 4 applies, except where this document overrides them.
• IEC 62722-2-1:2023 - Provides the LED luminaire performance methods and test conditions that are adapted for horticultural use in Clauses 4 and 7.
• IEC 63545 - Gives the safety requirements for horticultural luminaires, which Clause 4 requires in addition to performance.
• IEC 63013 - Provides LED package long-term luminous, radiant and photon flux maintenance reports that may be used in Clause 10 calculations.

What does the oSIST prEN IEC 63544:2026 document contain?

The document contains the core performance framework for horticultural LED luminaires, including formulas and definitions for photon flux, photon flux efficacy, photon intensity, photon irradiance, spectral distribution and maintenance factor. It gives the declaration items that belong on product datasheets, leaflets or websites, and it defines the measurement conditions and acceptance checks for type testing.

It also contains a test matrix that separates type A and type B luminaires, so users can see which measurements apply to which product type. Annex A provides research-based temperature guidance for plant heating effects, and Annex B gives practical construction recommendations for cleanable, greenhouse-suitable designs.

SLOVENSKI STANDARD
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
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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.

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
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
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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
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52 with the International Organization for Standardization (ISO) in accordance with conditions determined by
53 agreement between the two organizations.
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60 misinterpretation by any end user.
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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
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.
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).
IEC CDV 63544 © IEC 2025
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.
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
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
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
...