SIST EN 12665:2011
(Main)Light and lighting - Basic terms and criteria for specifying lighting requirements
Light and lighting - Basic terms and criteria for specifying lighting requirements
This standard defines basic terms for use in all lighting applications; specialist terms with limited applications are given in individual standards. This standard also sets out a framework for the specification of lighting requirements,giving details of aspects which shall be considered when setting those requirements.
Licht und Beleuchtung - Grundlegende Begriffe und Kriterien für die Festlegung von Anforderungen an die Beleuchtung
In dieser Europäischen Norm werden grundlegende Benennungen für alle lichttechnischen Anwendungen
definiert; spezielle Benennungen mit begrenztem Anwendungsbereich sind in besonders dafür vorgesehenen
Normen enthalten. Diese Norm legt auch Rahmenbedingungen für die Festlegung der Anforderungen an die
Beleuchtung fest. Dabei werden Einzelheiten zu den Gesichtpunkten dargestellt, die bei Festlegung dieser
Anforderungen zu berücksichtigen sind.
Lumière et éclairage - Termes de base et critères pour la spécification des exigences en éclairage
Svetloba in razsvetljava - Osnovni izrazi in merila za specifikacijo zahtev za razsvetljavo
Ta standard opredeljuje osnovne izraze za uporabo razsvetljave na vseh področjih; strokovni izrazi za omejena področja uporabe so podani v posameznih standardih. Ta standard tudi določa okvir za opredelitev zahtev za razsvetljavo, saj podaja podrobnosti o vidikih, ki jih je treba upoštevati pri določanju teh zahtev.
General Information
Relations
Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Svetloba in razsvetljava - Osnovni izrazi in merila za specifikacijo zahtev za razsvetljavoLicht und Beleuchtung - Grundlegende Begriffe und Kriterien für die Festlegung von Anforderungen an die BeleuchtungLumière et éclairage - Termes de base et critères pour la spécification des exigences en éclairageLight and lighting - Basic terms and criteria for specifying lighting requirements91.160.01Razsvetljava na splošnoLighting in general01.040.91Gradbeni materiali in gradnja (Slovarji)Construction materials and building (Vocabularies)ICS:Ta slovenski standard je istoveten z:EN 12665:2011SIST EN 12665:2011en,fr,de01-december-2011SIST EN 12665:2011SLOVENSKI
STANDARDSIST EN 12665:20041DGRPHãþD
SIST EN 12665:2011
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 12665
June 2011 ICS 01.040.91; 91.160.01 Supersedes EN 12665:2002English Version
Light and lighting - Basic terms and criteria for specifying lighting requirements
Lumière et éclairage - Termes de base et critères pour la spécification des exigences en éclairage
Licht und Beleuchtung - Grundlegende Begriffe und Kriterien für die Festlegung von Anforderungen an die Beleuchtung This European Standard was approved by CEN on 11 May 2011.
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. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member.
This European Standard exists 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, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre:
Avenue Marnix 17,
B-1000 Brussels © 2011 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 12665:2011: ESIST EN 12665:2011
EN 12665:2011 (E) 2 Contents Page Foreword .3Introduction .41 Scope .42 Normative references .53 Terms and definitions .53.1 Eye and vision .53.2 Light and colour .73.3 Lighting equipment. 153.4 Daylight . 213.5 Lighting installations . 233.6 Lighting measurements . 334 Framework for the specification of lighting requirements . 344.1 General . 344.2 Illuminance . 344.3 Luminance . 354.4 Glare . 354.5 Colour . 354.6 Energy . 354.7 Maintenance . 354.8 Measurements . 364.9 Accuracy . 36Annex A (informative)
Additional explanation of defined terms . 37Annex B (informative)
Index of terms. 40Annex C (informative)
A deviation . 46Annex ZA (informative)
Relationship between this European Standard and the Essential Requirements of EU Directive 2008/57/EC . 47Bibliography . 48 SIST EN 12665:2011
EN 12665:2011 (E) 3 Foreword This document (EN 12665:2011) has been prepared by Technical Committee CEN/TC 169 “Light and lighting”, the secretariat of which is held by DIN. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by December 2011, and conflicting national standards shall be withdrawn at the latest by December 2011. This document has been prepared under a mandate given to CEN/CENELEC/ETSI by the European Commission and the European Free Trade Association, and supports essential requirements of EU Directive 2008/57/EC. For relationship with EU Directive 2008/57/EC, see informative Annex ZA, which is an integral part of this document. This document supersedes EN 12665:2002. The main technical changes in this revision are: inclusion of terms previously absent collated from EN 1837, EN 1838, EN 12193, EN 12464-1,
EN 12464-2, EN 13032-1, EN 13032-2 and EN 15193. The significant change between EN 12665:2002 and EN 12665:2011 is within the scope of the document.
EN 12665:2002 defined basic terms for use in lighting applications, and specialist terms with limited applications were defined in individual standards. In practice this resulted in cases of similar terminology being used to define different concepts, and conversely different terms being used to describe similar concepts. Therefore EN 12665:2011 defines basic terms and definitions for use in all lighting applications. Furthermore some references have been updated. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: 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, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
SIST EN 12665:2011
EN 12665:2011 (E) 4 Introduction This European Standard specifies a basic framework to be used for the specification of lighting requirements. Where a term is contained in CIE Publication 17.4:1987 International Lighting Vocabulary (IEC 60050, International Electrotechnical Vocabulary, Chapter 845 Lighting), the term given in this standard is identical. For some terms additional explanation is given in informative Annex A. An index of terms is given in informative Annex B. The lighting requirements for a space are determined by the need to provide: adequate illumination for safety and movement; conditions which will facilitate visual performance and colour perception; acceptable visual comfort for the occupants in the space. The relative importance of these factors will vary for different applications. The lighting requirements for visual comfort and satisfaction of the occupants, will often exceed the requirements for visual performance alone. For example, the visual task may simply require the discrimination of black symbols on a white background; the colour rendering of the lighting is irrelevant to this task but it is important in making the appearance of the room and occupants acceptable. Variations of the lighting in space and time may also be important for visual satisfaction and can help to meet the interpersonal differences found within groups of people. Considerations should also be given to the energy used by lighting and to maintenance. The parameters which need to be specified to ensure good visual conditions and an efficient lighting installation are common to many applications. These are dealt with in Clause 4. 1 Scope This European Standard defines basic terms and definitions for use in all lighting applications. This European Standard also sets out a framework for the specification of lighting requirements, giving details of aspects which have to be considered when setting those requirements. SIST EN 12665:2011
EN 12665:2011 (E) 5 2 Normative references The following referenced documents are indispensable for the application 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. CIE 17.4:1987, International lighting vocabulary — Chapter 845: Lighting 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 Eye and vision 3.1.1 adaptation process by which the state of the visual system is modified by previous and present exposure to stimuli that can have various luminances, spectral distributions and angular subtenses NOTE 1
The terms light adaptation and dark adaptation are also used, the former when the luminances of the stimuli are of at least several candelas per square metre, and the latter when the luminances are of less than some hundredths of a candela per square metre. NOTE 2
Adaptation to specific spatial frequencies, orientations, sizes, etc. are recognized as being included in this definition. [IEC 60050-845:1987/CIE 17.4:1987; 845-02-07]
3.1.2 accommodation adjustment of the dioptric power of the crystalline lens by which the image of an object, at a given distance, is focused on the retina
[IEC 60050-845:1987/CIE 17.4:1987; 845-02-44]
3.1.3 visual acuity 1.
qualitatively: capacity for seeing distinctly fine details that have very small angular separation 2.
quantitatively: any of a number of measures of spatial discrimination such as the reciprocal of the value of the angular separation in minutes of arc of two neighbouring objects (points or lines or other specified stimuli) which the observer can just perceive to be separate
[IEC 60050-845:1987/CIE 17.4:1987; 845-02-43]
3.1.4 brightness luminosity (obsolete) attribute of a visual sensation according to which an area appears to emit more or less light [IEC 60050-845:1987/CIE 17.4:1987; 845-02-28] SIST EN 12665:2011
EN 12665:2011 (E) 6
3.1.5 contrast 1.
in the perceptual sense: assessment of the difference in appearance of two or more parts of a field seen simultaneously or successively (hence: brightness contrast, lightness contrast, colour contrast, simultaneous contrast, successive contrast, etc.) 2.
in the physical sense: quantity intended to correlate with the perceived brightness contrast, usually defined by one of a number of formulae which involve the luminances of the stimuli considered, for example: ûL/L near the luminance threshold, or L1/L2 for much higher luminances [IEC 60050-845:1987/CIE 17.4:1987; 845-02-47]
3.1.6 brightness contrast subjective assessment of the difference in brightness between two or more surfaces seen simultaneously or successively 3.1.7 colour contrast subjective assessment of the difference in colour between two or more surfaces seen simultaneously or successively 3.1.8 glare condition of vision in which there is discomfort or a reduction in the ability to see details or objects, caused by an unsuitable distribution or range of luminance, or to extreme contrasts [IEC 60050-845:1987/CIE 17.4:1987; 845-02-52]
3.1.9 flicker impression of unsteadiness of visual sensation induced by a light stimulus whose luminance or spectral distribution fluctuates with time [IEC 60050-845:1987/CIE 17.4:1987; 845-02-49]
3.1.10 visual field area or extent of physical space visible to an eye at a given position and direction of view NOTE
It should be stated whether the visual field is monocular or binocular. 3.1.11 visual performance performance of the visual system as measured for instance by the speed and accuracy with which a visual task is performed [IEC 60050-845:1987/CIE 17.4:1987; 845-09-04]
3.1.12 visual comfort subjective condition of visual well-being induced by the visual environment SIST EN 12665:2011
EN 12665:2011 (E) 7 3.1.13 reaction time minimum time interval between the occurrence of an event demanding immediate action and the response to the event (unit: s) NOTE The reaction time includes the time needed for perception, taking a decision and acting. 3.1.14 visual task visual elements of the activity being undertaken NOTE The main visual elements are the size of the structure, its luminance, its contrast against the background and its duration. 3.2 Light and colour 3.2.1 luminous flux - quantity derived from radiant flux -e by evaluting the radiation according to its action upon the CIE standard photometric observer (unit: lm) NOTE 1 For photopic vision ()()λλλλφφdddK0mVe×=∫∞ where
Φ
is the luminous flux;
()λλφdde is the spectral distribution of the radiant flux;
V()
is the spectral luminous efficiency function. NOTE 2 For the values of Km (photopic vision) and K′m (scotopic vision), see IEC 60050-845:1987/CIE 17.4:1987;
845-01-56. [IEC 60050-845:1987/CIE 17.4:1987; 845-01-25]
3.2.2 luminous intensity (of a source, in a given direction) I quotient of the luminous flux dΦ leaving the source and propagated in the element of solid angle d containing the given direction, by the element of solid angle (unit: cd = lm ⋅ sr -1) Ωφdd=I where I
is the luminous intensity of a source in a given direction; dΦ is the luminous flux leaving the source; dΩ is the solid angle. SIST EN 12665:2011
EN 12665:2011 (E) 8 [IEC 60050-845:1987/CIE 17.4:1987; 845-01-31]
3.2.3 luminance (in a given direction, at a given point of a real or imaginary surface) L quantity defined by the equation (unit: cd ⋅ m-2 = lm ⋅ m -2 ⋅ sr -1) A-Ldcosddϑ= where L
is the luminance in a given direction or at a given point of a surface; φd is the luminous flux transmitted by an elementary beam passing through the given point and propagating in the solid angle Ωd containing the given direction; dA
is the area of a section of that beam containing the given point; dΩ
is the solid angle; ϑ
is the angle between the normal to that section and the direction of the beam. NOTE See notes 1 to 5 to IEC 60050-845:1987/CIE 17.4:1987; 845-01-34. [IEC 60050-845:1987/CIE 17.4:1987; 845-01-35]
3.2.4 average luminance L luminance averaged over the specified surface or solid angle (unit: cd ⋅ m-2) 3.2.5 minimum luminance Lmin lowest luminance of any relevant point on the specified surface (unit: cd ⋅ m-2) NOTE The relevant points at which the luminances are determined should be specified in the appropriate application standard. 3.2.6 maximum luminance Lmax highest luminance of any relevant point on the specified surface (unit: cd ⋅ m-2) NOTE The relevant points at which the luminances are determined should be specified in the appropriate application standard. 3.2.7 maintained luminance Lm minimum average luminance (unit: cd ⋅ m-2) NOTE 1 Value below which average luminance should not fall. NOTE 2 It is the average luminance at the time maintenance should be carried out. SIST EN 12665:2011
EN 12665:2011 (E) 9 3.2.8 initial average luminance Li average luminance when the installation is new (unit: cd ⋅ m-2) 3.2.9 luminance contrast photometric quantity intended to correlate with brightness contrast, usually defined by one of a number of equations which involve the luminances of the stimuli considered (see also 3.1.5 [IEC 60050-845:1987/CIE 17.4:1987; 845-02-47]) NOTE Luminance contrast can be defined as luminance ratio
C1 = L2/L1 (usually for successive stimuli), or by the following equation C2 = (L2 - L1) / L1 (usually for surfaces viewed simultaneously), when the areas of different luminance are comparable in size and it is desired to take an average, the following equation can be used instead C3 = (L2 - L1) / 0,5(L2 + L1) where
L1
is the luminance of the background, or largest part of the visual field; and L2 is the luminance of the object; L2 is the luminance of the object.
3.2.10 illuminance (at a point of a surface) E quotient of the luminous flux d- incident on an element of the surface containing the point, by the area dù of that element (unit: lx = lm ⋅ m-2) NOTE Equivalent definition: Integral, taken over the hemisphere visible from the given point, of the expression
L ⋅ cos
⋅ d, where L is the luminance at the given point in the various directions of the incident elementary beams of solid angle d, and
is the angle between any of these beams and the normal to the surface at the given point. ∫Ω=Φ=srLAEπθ2dcosdd where E
is the illuminance at a point of a surface; L
is the luminance at the given point in the various directions of the incident elementary beams of solid angle dΩ; ,
is the angle between an incident beam and the normal to the surface at the given point; dΩ
is the solid angle. [IEC 60050-845:1987/CIE 17.4:1987; 845-01-38]
3.2.11 average illuminance E illuminance averaged over the specified surface (unit: lx) SIST EN 12665:2011
EN 12665:2011 (E) 10 NOTE In practice this can be derived either from the total luminous flux falling on the surface divided by the total area of the surface, or alternatively from an average of the illuminances at a representative number of points on the surface. 3.2.12 minimum illuminance Emin lowest illuminance at any relevant point on the specified surface (unit: lx) 3.2.13 maximum illuminance Emax highest illuminance at any relevant point on the specified surface (unit: lx) 3.2.14 maintained illuminance mE minimum average illuminance (unit: lx) NOTE 1 Value below which the average illuminance on the specified area should not fall. NOTE 2 It is the average illuminance at the time maintenance should be carried out. 3.2.15 initial illuminance iE average illuminance on the specified surface when the installation is new (unit: lx) 3.2.16 spherical illuminance (at a point) Eo total luminous flux falling on the whole surface of a very small sphere located at the specified point divided by the surface area of the sphere (unit: lx) (see also IEC 60050-845:1987/CIE 17.4:1987; 845-01-40 spherical irradiance)
3.2.17 hemispherical illuminance (at a point) Ehs total luminous flux falling on the curved surface of a very small hemisphere located at the specified point divided by the curved surface area of the hemisphere (unit: lx) NOTE The base of the hemisphere is taken to be horizontal unless stated otherwise. 3.2.18 cylindrical illuminance (at a point, for a direction) Ez total luminous flux falling on the curved surface of a very small cylinder located at the specified point divided by the curved surface area of the cylinder (unit: lx) NOTE The axis of the cylinder is taken to be vertical unless stated otherwise. (see also IEC 60050-845:1987/CIE 17.4:1987; 845-01-41 cylindrical irradiance)
3.2.19 semi-cylindrical illuminance (at a point) Esz total luminous flux falling on the curved surface of a very small semi-cylinder located at the specified point, divided by the curved surface area of the semi-cylinder (unit: lx) SIST EN 12665:2011
EN 12665:2011 (E) 11 NOTE The axis of the semi-cylinder is taken to be vertical unless stated otherwise. The direction of the curved surface should be specified. 3.2.20 uniformity (luminance, illuminance) Uo ratio of minimum illuminance (luminance) to average illuminance (luminance) on (of) a surface (see also IEC 60050-845:1987/CIE 17.4; 845-09-58 uniformity ratio of illuminance) NOTE Use is also made of the ratio of minimum illuminance to maximum illuminance in which case this should be specified explicitly. 3.2.21 reference surface surface on which illuminance is measured or specified [IEC 60050-845:1987/CIE 17.4:1987; 845-09-49]
3.2.22 disability glare glare that impairs the vision of objects without necessarily causing discomfort [IEC 60050-845:1987/CIE 17.4:1987; 845-02-57]
3.2.23 discomfort glare glare that causes discomfort without necessarily impairing the vision of objects [IEC 60050-845:1987/CIE 17.4:1987; 845-02-56]
3.2.24 veiling reflections specular reflections that appear on the object viewed and that partially or wholly obscure the details by reducing contrast [IEC 60050-845:1987/CIE 17.4:1987; 845-02-55]
3.2.25 luminous environment lighting considered in relation to its physiological and psychological effects [IEC 60050-845:1987/CIE 17.4:1987; 845-09-03]
3.2.26 colour rendering effect of an illuminant on the colour appearance of objects by conscious or subconscious comparison with their colour appearance under a reference illuminant NOTE In German, the term “Farbwiedergabe” is also applied to colour reproduction. [IEC 60050-845:1987/CIE 17.4:1987; 845-02-59]
3.2.27 CIE 1974 general colour rendering index Ra mean of the CIE 1974 special colour rendering indices for a specified set of eight test colour samples [IEC 60050-845:1987/CIE 17.4:1987; 845-02-63] SIST EN 12665:2011
EN 12665:2011 (E) 12
3.2.28 colour stimulus visible radiation entering the eye and producing a sensation of colour, either chromatic or achromatic [IEC 60050-845:1987/CIE 17.4:1987; 845-03-02]
3.2.29 tristimulus values (of a colour stimulus) amounts of the three reference colour stimuli, in a given trichromatic system, required to match the colour of the stimulus considered NOTE In the CIE standard colorimetric systems, the tristimulus values are represented by the symbols X, Y, Z and X10, Y10, Z10. [IEC 60050-845:1987/CIE 17.4:1987; 845-03-22]
3.2.30 chromaticity coordinates ratio of each of a set of three tristimulus values to their sum NOTE 1 As the sum of the three chromaticity coordinates equals 1, two of them are sufficient to define a chromaticity. NOTE 2 In the CIE standard colorimetric systems, the chromaticity coordinates are presented by the symbols x, y, z and x10, y10, z10. [IEC 60050-845:1987/CIE 17.4:1987; 845-03-33]
3.2.31 chromaticity property of a colour stimulus defined by its chromaticity coordinates, or by its dominant or complementary wavelength and purity taken together [IEC 60050-845:1987/CIE 17.4:1987; 845-03-34]
3.2.32 colour temperature Tc temperature of a Planckian radiator whose radiation has the same chromaticity as that of a given stimulus (unit: K) NOTE The reciprocal colour temperature is also used, unit: K-1. [IEC 60050-845:1987/CIE 17.4:1987; 845-03-49]
3.2.33 correlated colour temperature Tcp temperature of the Planckian radiator whose perceived colour most closely resembles that of a given stimulus at the same brightness and under specified viewing conditions (unit: K) NOTE 1 The recommended method of calculating the correlated colour temperature of a stimulus is to determine on a chromaticity diagram the temperature corresponding to the point on the Planckian locus that is intersected by the agreed isotemperature line containing the point representing the stimulus (see CIE Publication No 15). NOTE 2 Reciprocal correlated colour temperature is used rather than reciprocal colour temperature whenever correlated colour temperature is appropriate. [IEC 60050-845:1987/CIE 17.4:1987; 845-03-50] SIST EN 12665:2011
EN 12665:2011 (E) 13
3.2.34 fusion frequency critical flicker frequency (for a given set of conditions) frequency of alternation of stimuli above which flicker is not perceptible (unit: Hz) [IEC 60050-845:1987/CIE 17.4:1987; 845-02-50]
3.2.35 reflectance (for incident radiation of given spectral composition, polarization and geometrical distribution)
ratio of the reflected radiant or luminous flux to the incident flux in the given conditions (unit: 1) [IEC 60050-845:1987/CIE 17.4:1987; 845-04-58]
3.2.36 transmittance (for incident radiation of given spectral composition, polarization and geometrical distribution) τ ratio of the transmitted radiant or luminous flux to the incident flux in the given conditions (unit: 1) [IEC 60050-845:1987/CIE 17.4:1987; 845-04-59]
3.2.37 absorptance . ratio of the absorbed radiant or luminous flux to the incident flux under specified conditions (unit: 1) [IEC 60050-845:1987/CIE 17.4:1987; 845-04-75]
3.2.38 photometry measurement of quantities referring to radiation as evaluated according to a given spectral luminous efficiency function, e.g. V() or V’()
[IEC 60050-845:1987/CIE 17.4:1987; 845-05-09]
3.2.39 access zone luminance eye adaptation luminance in the access zone (unit: cd · m-2)
3.2.40 contrast revealing coefficient qc quotient between the luminance (L) of the road surface, and the vertical illuminance (υE) at that point (unit: cd · m-2 · lx-1) υELqc= where qc is the contrast revealing coefficient; L
is the luminance of the road surface at the point; Ev
is the vertical illuminance at the point SIST EN 12665:2011
EN 12665:2011 (E) 14 3.2.41 diversity (luminance, illuminance) extreme uniformity Ud ratio of minimum illuminance (luminance) to maximum illuminance (luminance) on (of) a surface (see also 3.2.20 uniformity) 3.2.42 equivalent veiling luminance (for disability glare or veiling reflections) Lve luminance that, when added by superposition to the luminance of both the adapting background and the object, makes the luminance threshold or the luminance difference threshold the same under the two following conditions: (1) glare present, but no additional luminance; (2) additional luminance present, but no glare (unit: cd · m-2) [IEC 60050-845:1987/CIE 17.4:1987; 845-02-58]
3.2.43 glare rating limit RGL upper limit of glare by the CIE Glare Rating system 3.2.44 interior zone luminance (of a tunnel) Lin average road surface luminance of a transverse strip at a given location in the interior zone of the tunnel (as a function of the measurement grid) (unit: cd · m-2) 3.2.45 L20 access luminance (of a tunnel) average luminance contained in a conical field of view, subtending an angle of 20º with the apex at the position of the eye of an approaching driver and aimed at the centre of the tunnel mouth (unit: cd · m-2) NOTE L20 access luminance is assessed from a point at a distance equal to the stopping distance from the tunnel portal at the middle of the relevant carriageway or traffic lane. 3.2.46 longitudinal uniformity (of road surface luminance of a carriageway) Ul ratio of the minimum to the maximum road surface luminance found in a line in the centre along a driving lane NOTE The longitudinal uniformity is considered for each driving lane. 3.2.47 obtrusive light spill light which because of quantitative, directional or spectral attributes in a given context gives rise to annoyance, discomfort, distraction or reduction in the ability to see essential information NOTE 1 In the case of outdoor sports lighting installations, obtrusive light is considered around the installation and not for spectators, referees or players within the sports area. NOTE 2 In the case of large tertiary buildings with predominantly glazed facades, interior lighting may be considered as obtrusive light if it gives rise to annoyance, discomfort, distraction or a reduction in the ability to see essential information due to light spilling outside of the building structure. SIST EN 12665:2011
EN 12665:2011 (E) 15 3.2.48 spill light stray light light emitted by a lighting installation which falls outside the boundaries of the property for which the lighting installation is designed 3.2.49 threshold zone luminance Lth ave
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