THE BOOK OF LIGHT · EVIDENCE
Technical verification records
Open a record to inspect its details and follow its source links.
- reviewed
- 2026-10-04
- facts
Record 1
- id
- photometry-flux
- topic
- Luminous flux
- fact
- Luminous flux measures radiant-energy flow after weighting it for a standardized visual response; its unit is the lumen.
- source title
- luminous flux
- source url
- https://ies.org/definitions/luminous-flux/
- limitation
- Ordinary luminous-flux values use the photopic response unless another response is specified.
- checked date
- 2026-10-04
- source type
- IES public glossary
Record 2
- id
- photometry-illuminance
- topic
- Illuminance
- fact
- Illuminance describes the density of luminous flux arriving at a surface.
- source title
- illuminance
- source url
- https://ies.org/definitions/illuminance/
- limitation
- It describes incident light, not subjective brightness or the light returned toward a viewer.
- checked date
- 2026-10-04
- source type
- IES public glossary
Record 3
- id
- photometry-lux
- topic
- Lux
- fact
- One lux corresponds to one lumen arriving per square metre.
- source title
- lux
- source url
- https://ies.org/definitions/lux/
- limitation
- This is a unit relationship, not a recommended design target.
- checked date
- 2026-10-04
- source type
- IES public glossary
Record 4
- id
- photometry-intensity
- topic
- Luminous intensity
- fact
- Luminous intensity describes luminous flux per unit solid angle in a particular direction and is expressed in candelas.
- source title
- luminous intensity
- source url
- https://ies.org/definitions/luminous-intensity/
- limitation
- The point-source definition is applied in practice when source dimensions are small relative to observation distance.
- checked date
- 2026-10-04
- source type
- IES public glossary
Record 5
- id
- photometry-luminance
- topic
- Luminance
- fact
- Luminance is a directional photometric quantity associated with light leaving, passing through, or arriving at a surface.
- source title
- luminance
- source url
- https://ies.org/definitions/luminance/
- limitation
- Do not use it as a synonym for illuminance.
- checked date
- 2026-10-04
- source type
- IES public glossary
Record 6
- id
- perception-brightness
- topic
- Brightness and luminance
- fact
- Perceived brightness depends partly on measurable luminance and partly on observation conditions, including the eye's adaptation.
- source title
- luminance
- source url
- https://ies.org/definitions/luminance/
- limitation
- A subjective sensation cannot be replaced completely by a single physical measurement.
- checked date
- 2026-10-04
- source type
- IES public glossary
Record 7
- id
- vision-photopic
- topic
- Photopic vision
- fact
- Photopic vision is mediated primarily by the retina's cones.
- source title
- photopic vision
- source url
- https://ies.org/definitions/photopic-vision/
- limitation
- The source gives approximate adaptation conditions; this text intentionally does not turn them into design thresholds.
- checked date
- 2026-10-04
- source type
- IES public glossary
Record 8
- id
- vision-scotopic
- topic
- Scotopic vision
- fact
- Scotopic vision is mediated primarily by the retina's rods.
- source title
- scotopic vision
- source url
- https://ies.org/definitions/scotopic-vision/
- limitation
- The source describes very low adaptation luminance; it is not an instruction for lighting design.
- checked date
- 2026-10-04
- source type
- IES public glossary
Record 9
- id
- vision-mesopic
- topic
- Mesopic vision
- fact
- Mesopic vision occupies the adaptation range between scotopic and photopic conditions.
- source title
- mesopic vision
- source url
- https://ies.org/definitions/mesopic-vision/
- limitation
- The fully adapted-eye condition matters; avoid presenting boundaries as universal instantaneous changes.
- checked date
- 2026-10-04
- source type
- IES public glossary
Record 10
- id
- color-cct
- topic
- Correlated color temperature
- fact
- CCT associates a source's chromaticity with the temperature of the closest-matching blackbody chromaticity.
- source title
- correlated color temperature (CCT) of a light source
- source url
- https://ies.org/definitions/correlated-color-temperature-cct-of-a-light-source/
- limitation
- It is a chromaticity descriptor, not the physical temperature of an LED.
- checked date
- 2026-10-04
- source type
- IES public glossary
Record 11
- id
- color-tm30
- topic
- TM-30 color rendition
- fact
- TM-30 evaluates overall color fidelity and gamut area together with hue-specific fidelity, chroma shifts, and hue shifts.
- source title
- Technical Memorandum: IES Method for Evaluating Light Source Color Rendition
- source url
- https://store.ies.org/product/technical-memorandum-ies-method-for-evaluating-light-source-color-rendition/
- limitation
- Public catalog description verified as ANSI/IES TM-30-24+E1; the full calculation standard was not reproduced.
- checked date
- 2026-10-04
- source type
- IES public standard catalog
Record 12
- id
- color-tm40
- topic
- CCT and Duv
- fact
- TM-40 describes computation of CCT and distance from the Planckian locus, Duv, using a light source's chromaticity coordinates.
- source title
- Technical Memorandum: IES Method for Determining Correlated Color Temperature (CCT) and Distance from the Planckian Locus of Light Sources
- source url
- https://store.ies.org/product/technical-memorandum-ies-method-for-determining-correlated-color-temperature-cct-and-distance-from-the-planckian-locus-of-light/
- limitation
- Public catalog description identifies ANSI/IES TM-40-24. Do not present full methods or restrictions without consulting the standard.
- checked date
- 2026-10-04
- source type
- IES public standard catalog
Record 13
- id
- glare-discomfort
- topic
- Discomfort glare
- fact
- Discomfort glare causes discomfort but does not necessarily reduce visibility or visual performance.
- source title
- discomfort glare
- source url
- https://ies.org/definitions/discomfort-glare/
- limitation
- Keep separate from disability glare, although both can occur together.
- checked date
- 2026-10-04
- source type
- IES public glossary
Record 14
- id
- glare-disability
- topic
- Disability glare
- fact
- Stray light inside the eye can reduce retinal-image contrast and thereby reduce visibility or visual performance.
- source title
- disability glare
- source url
- https://ies.org/definitions/disability-glare/
- limitation
- A source that causes discomfort can also cause disability glare.
- checked date
- 2026-10-04
- source type
- IES public glossary
Record 15
- id
- glare-ugr
- topic
- Unified glare rating
- fact
- UGR is a measure of discomfort produced by a lighting system.
- source title
- unified glare rating, UGR
- source url
- https://ies.org/definitions/unified-glare-rating-ugr/
- limitation
- This definition does not establish a universal acceptable UGR or a product-independent rating.
- checked date
- 2026-10-04
- source type
- IES public glossary
Record 16
- id
- temporal-light
- topic
- Flicker terminology
- fact
- The common word flicker can refer both to temporal light modulation and to visual artifacts perceived in response to it.
- source title
- flicker
- source url
- https://ies.org/definitions/flicker/
- limitation
- IES cautions that the term can be non-specific; distinguish the physical modulation from the response.
- checked date
- 2026-10-04
- source type
- IES public glossary
Record 17
- id
- daylight-design
- topic
- Integrated daylighting
- fact
- Daylighting design must address occupant comfort, lighting quality, and energy efficiency together across changing daylight and weather conditions.
- source title
- Designing and Specifying Daylighting for Buildings
- source url
- https://store.ies.org/product/lp-3-20-lighting-practice-designing-and-specifying-daylighting-for-buildings/
- limitation
- Public catalog synopsis only; no numerical criteria or proprietary tables reproduced.
- checked date
- 2026-10-04
- source type
- IES public standard catalog
Record 18
- id
- daylight-integration
- topic
- Daylight and electric lighting
- fact
- IES daylighting guidance includes shading, glazing, electric-light integration, switching, dimming, and photosensing strategies.
- source title
- Designing and Specifying Daylighting for Buildings
- source url
- https://store.ies.org/product/lp-3-20-lighting-practice-designing-and-specifying-daylighting-for-buildings/
- limitation
- Supported by the public table of contents; it is a scope description, not a detailed control algorithm.
- checked date
- 2026-10-04
- source type
- IES public standard catalog
Record 19
- id
- controls-strategies
- topic
- Lighting control strategies
- fact
- IES education addresses occupancy-based controls, daylighting controls, and lighting-reduction strategies in interior and exterior design.
- source title
- Level 3: Codes, Controls, Compliance – Elements of Successful Lighting Control Designs
- source url
- https://elearning.ies.org/products/level-3-codes-controls-compliance-elements-of-successful-lighting-control-designs
- limitation
- Public course objectives establish the topics; local adopted energy codes determine actual compliance requirements.
- checked date
- 2026-10-04
- source type
- IES public course description
Record 20
- id
- controls-tunable
- topic
- Tunable white
- fact
- Tunable-white lighting varies the correlated color temperature of a white-light source through spectral tuning.
- source title
- tunable white
- source url
- https://ies.org/definitions/tunable-white/
- limitation
- Changing CCT does not by itself demonstrate a health outcome.
- checked date
- 2026-10-04
- source type
- IES public glossary
- standards
- verified on
- 2026-10-04
- scope
- Public IES webstore metadata only. No numeric requirements or full standards copied. Listed identifier is what official product page currently displays, not independent certification that no newer revision exists.
- standards
Optical and Electrical Measurements of Solid State Lighting Products
- key
- LM-79
- identifier
- ANSI/IES LM-79-24
- title
- Optical and Electrical Measurements of Solid State Lighting Products
- edition
- 2024
- purpose
- Measures SSL product flux, electrical input, efficacy, distribution, spectrum and color under standardized conditions.
- url
- https://store.ies.org/product/optical-and-electrical-measurements-of-solid-state-lighting-products/
- source ref
- turn43view0
Measuring Maintenance of Light Output Characteristics of Solid-State Light Sources
- key
- LM-80
- identifier
- ANSI/IES LM-80-21
- title
- Measuring Maintenance of Light Output Characteristics of Solid-State Light Sources
- edition
- 2021
- purpose
- Measures output and color maintenance of LED packages, arrays and modules under controlled conditions.
- url
- https://store.ies.org/product/lm-80-21-measuring-maintenance-of-light-output-characteristics-of-solid-state-light-sources/
- source ref
- turn44view1
Projecting Long-Term Luminous, Photon, and Radiant Flux Maintenance of LED Light Sources
- key
- TM-21
- identifier
- ANSI/IES TM-21-21
- title
- Projecting Long-Term Luminous, Photon, and Radiant Flux Maintenance of LED Light Sources
- edition
- 2021
- purpose
- Projects source flux maintenance from LM-80 data, with limits on extrapolation.
- url
- https://store.ies.org/product/tm-21-21-projecting-long-term-luminous-photon-and-radiant-flux-maintenance-of-led-light-sources/
- source ref
- turn44view0
IES Standard File Format for the Electronic Transfer of Photometric Data and Related Information
- key
- LM-63
- identifier
- ANSI/IES LM-63-19(R25)
- title
- IES Standard File Format for the Electronic Transfer of Photometric Data and Related Information
- edition
- 2019; reaffirmation 2025
- purpose
- Defines photometric data exchange structure, keywords, file conventions and IES-file examples.
- url
- https://store.ies.org/product/approved-method-ies-standard-file-format-for-the-electronic-transfer-of-photometric-data-and-related-information/
- source ref
- turn44view2
IES Method for Evaluating Light Source Color Rendition
- key
- TM-30
- identifier
- ANSI/IES TM-30-24+E1
- title
- IES Method for Evaluating Light Source Color Rendition
- edition
- 2024; errata E1
- purpose
- Evaluates overall color fidelity and gamut, and hue-specific fidelity, chroma and hue shifts.
- url
- https://store.ies.org/product/technical-memorandum-ies-method-for-evaluating-light-source-color-rendition/
- source ref
- turn43view1
Luminaire Classification System for Outdoor Luminaires
- key
- TM-15
- identifier
- ANSI/IES TM-15-20
- title
- Luminaire Classification System for Outdoor Luminaires
- edition
- 2020
- purpose
- Defines LCS and BUG ratings for outdoor luminaire distribution; replaces the deprecated cutoff system.
- url
- https://store.ies.org/product/tm-15-20-technical-memorandum-luminaire-classification-system-for-outdoor-luminaires/
- source ref
- turn43view2
Lighting Roadway and Parking Facilities
- key
- RP-8
- identifier
- ANSI/IES RP-8-25+E2
- title
- Lighting Roadway and Parking Facilities
- edition
- 2025; errata E2
- purpose
- Roadway design and maintenance, intersections, tunnels, work zones, parking lots and garages.
- url
- https://store.ies.org/product/recommended-practice-lighting-roadway-and-parking-facilities/
- source ref
- turn41view0
Lighting Office Spaces
- key
- RP-1
- identifier
- ANSI/IES RP-1-24
- title
- Lighting Office Spaces
- edition
- 2024
- purpose
- Office quality, glare, visual displays, controls, sustainability and specific spaces.
- url
- https://store.ies.org/product/recommended-practice-lighting-office-spaces/
- source ref
- turn41view2
Lighting Sports and Recreational Areas
- key
- RP-6
- identifier
- ANSI/IES RP-6-24
- title
- Lighting Sports and Recreational Areas
- edition
- identifier 2024; publisher and citation 2025
- purpose
- Lighting for sports facilities except professional, including indoor/outdoor applications and sport-specific considerations.
- url
- https://store.ies.org/product/recommended-practice-lighting-sports-and-recreational-areas/
- source ref
- turn41view1
Lighting and the Visual Environment for Older Adults and the Visually Impaired
- key
- RP-28
- identifier
- ANSI/IES RP-28-25
- title
- Lighting and the Visual Environment for Older Adults and the Visually Impaired
- edition
- 2025
- purpose
- Application guidance for older adults and visually impaired users; title-only purpose verification.
- url
- https://store.ies.org/product/recommended-practice-lighting-and-the-visual-environment-for-older-adults-and-the-visually-impaired/
- source ref
- turn34search6
Lighting Educational Facilities
- key
- RP-3
- identifier
- ANSI/IES RP-3-26
- title
- Lighting Educational Facilities
- edition
- 2026
- purpose
- Classrooms, corridors, labs, shops and social spaces in schools and universities; daylighting and controls updates.
- url
- https://store.ies.org/product/recommended-practice-lighting-educational-facilities/
- source ref
- turn41view3
Lighting Hospital and Healthcare Facilities
- key
- RP-29
- identifier
- ANSI/IES RP-29-25
- title
- Lighting Hospital and Healthcare Facilities
- edition
- 2025
- purpose
- Healthcare-specific lighting challenges, quality, comfort, function, safety and room types.
- url
- https://store.ies.org/product/recommended-practice-lighting-hospital-and-healthcare-facilities/
- source ref
- turn44view5
IES Spatial Daylight Autonomy (sDA) and Annual Sunlight Exposure (ASE)
- key
- LM-83
- identifier
- ANSI/IES LM-83-23
- title
- IES Spatial Daylight Autonomy (sDA) and Annual Sunlight Exposure (ASE)
- edition
- identifier 2023; publisher field 2022
- purpose
- Annual climate-based daylight simulation metrics with hourly weather data and shading behavior.
- url
- https://store.ies.org/product/approved-method-ies-spatial-daylight-autonomy-sda-and-annual-sunlight-exposure-ase/
- source ref
- turn44view3
Designing and Specifying Daylighting for Buildings
- key
- LP-3
- identifier
- ANSI/IES LP-3-20+E1
- title
- Designing and Specifying Daylighting for Buildings
- edition
- 2020; errata E1
- purpose
- Integrated daylight design: comfort, glare, heat gain, apertures, glazing, shading and electric-light integration.
- url
- https://store.ies.org/product/lp-3-20-lighting-practice-designing-and-specifying-daylighting-for-buildings/
- source ref
- turn43search0
Lighting Control Systems – Properties, Selection, and Specification
- key
- LP-6
- identifier
- ANSI/IES LP-6-25
- title
- Lighting Control Systems – Properties, Selection, and Specification
- edition
- 2025
- purpose
- Control purposes, strategies, equipment, protocols, documentation and commissioning considerations.
- url
- https://store.ies.org/product/lighting-practice-lighting-control-systems-properties-selection-and-specification/
- source ref
- turn44view4
- unresolved
Record 1
- key
- RP-20
- note
- No current official standalone RP-20 product verified. Use current RP-8-25+E2 for parking applications; chapter 17 explicitly covers parking lots and garages. Do not label RP-20 current or formally withdrawn without additional official evidence.
- metadata anomalies
- LM-63 product description refers incorrectly to fluorescent life tests; identifier, title and table of contents support photometric exchange purpose.RP-1-24 citation line says 2020 while publisher field says 2024.RP-3-26 description mentions RP-1-25 while current office product identifier is RP-1-24.RP-6-24 publisher/citation year is 2025; preserve identifier and report publication year separately.LM-83-23 publisher field says 2022; preserve identifier rather than silently correcting metadata.
- editorial notes
- These are standards references, not claims of IES endorsement or compliance.Paywalled standards should be linked, not reproduced. Project-specific numerical criteria need authorized access and qualified design review.LM-80/TM-21 concern LED-source maintenance, not a promise that every driver, optic or complete luminaire lasts that long. Official IES lifetime position: https://ies.org/advocacy/ps-10-18/