Academic Articles and Research Archives - All Things Lighting® Association https://www.allthingslighting.org/category/academic-articles-and-research/ Illuminating the Complicated! Wed, 05 Nov 2025 00:00:55 +0000 en-US hourly 1 https://www.allthingslighting.org/wp-content/uploads/2023/08/cropped-ATLA-favicon2-32x32.jpg Academic Articles and Research Archives - All Things Lighting® Association https://www.allthingslighting.org/category/academic-articles-and-research/ 32 32 Refinements to the Worthing Relationship – A Quantum Version of Wien’s Displacement Law https://www.allthingslighting.org/refinements-to-the-worthing-relationship-a-quantum-version-of-wiens-displacement-law/ https://www.allthingslighting.org/refinements-to-the-worthing-relationship-a-quantum-version-of-wiens-displacement-law/#respond Wed, 05 Nov 2025 00:00:55 +0000 https://www.allthingslighting.org/?p=5227 Refinements to the Worthing Relationship – A Quantum Version of Wien’s Displacement Law Eric Bretschneider, Ph.D. Abstract Wien’s Displacement Law is a simple equation that allows calculation of the peak wavelength for a black body light source as a function of temperature. However, not all uses of light are based on radiant flux. In particular, […]

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]]> https://www.allthingslighting.org/refinements-to-the-worthing-relationship-a-quantum-version-of-wiens-displacement-law/feed/ 0 Finding the Danger Zone of the Circadian Stimulus Model: A Summary https://www.allthingslighting.org/finding-the-danger-zone-of-the-circadian-stimulus-model-a-summary/ https://www.allthingslighting.org/finding-the-danger-zone-of-the-circadian-stimulus-model-a-summary/#respond Tue, 04 Nov 2025 23:55:01 +0000 https://www.allthingslighting.org/?p=5248 Author: Alexander Willemsen, Degree of Master of Science of Engineering Based on a paper authored by Eric Bretschneider, Ph.D. The Circadian Stimulus (CS) model is one of the most well-known models for quantifying the circadian impact of lighting. One striking feature that separates the model from other contemporary circadian lighting models is its discontinuous action […]

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]]> https://www.allthingslighting.org/finding-the-danger-zone-of-the-circadian-stimulus-model-a-summary/feed/ 0 Can Designs and Measurements Based on the Circadian Stimulus Model Stand the Test of Time? https://www.allthingslighting.org/can-designs-and-measurements-based-on-the-circadian-stimulus-model-stand-the-test-of-time/ https://www.allthingslighting.org/can-designs-and-measurements-based-on-the-circadian-stimulus-model-stand-the-test-of-time/#respond Tue, 13 Aug 2024 06:01:18 +0000 https://www.allthingslighting.org/?p=4817 Author: Eric Bretschneider, Ph.D INTRODUCTION When considering the potential circadian impact of lighting, lighting designers have a choice between three different models: melanopic equivalent daylight illuminance, or m-EDI [CIE 2018]; equivalent melanopic lux, or EML [WELL v2]; and circadian light, or CLA [UL 2019]. Both m-EDI and EML have a continuous action spectrum, which means […]

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]]> https://www.allthingslighting.org/can-designs-and-measurements-based-on-the-circadian-stimulus-model-stand-the-test-of-time/feed/ 0 Lighting Uniformity in Horticulture https://www.allthingslighting.org/lighting-uniformity-in-horticulture/ https://www.allthingslighting.org/lighting-uniformity-in-horticulture/#respond Fri, 24 Jun 2022 03:34:28 +0000 https://www.allthingslighting.org/?p=2824 Written in 2015, “Greenhouse Design and Control” (Ponce et al. 2015) is extraordinarily comprehensive in its coverage of greenhouse design issues, from site selection through structural load bearing analysis and ventilation technologies to greenhouse automation using adaptive neural fuzzy inference systems. On the topic of greenhouse lighting, however, it has only this to say: “The light level in the greenhouse should be adequate and uniform for crop growth.”

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]]> https://www.allthingslighting.org/lighting-uniformity-in-horticulture/feed/ 0 Modeling Spherical Irradiance for UV-C Air Disinfection https://www.allthingslighting.org/modeling-spherical-irradiance-for-uv-c-air-disinfection/ https://www.allthingslighting.org/modeling-spherical-irradiance-for-uv-c-air-disinfection/#respond Fri, 20 May 2022 13:29:02 +0000 https://www.allthingslighting.org/?p=2791 We have been using ultraviolet radiation as a means of disinfection for over a century. However, it has been the unfortunate events of the past year that have led to an explosion of interest in ultraviolet germicidal irradiation (UVGI) systems. From mercury vapour and pulsed xenon lamps to excimer lamps and ultraviolet LEDs, there have […]

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]]> https://www.allthingslighting.org/modeling-spherical-irradiance-for-uv-c-air-disinfection/feed/ 0 Visible Light Disinfection https://www.allthingslighting.org/visible-light-disinfection/ https://www.allthingslighting.org/visible-light-disinfection/#respond Thu, 19 May 2022 19:45:38 +0000 https://www.allthingslighting.org/?p=2760 In summary, visible light disinfection technology may be useful in some applications, but it is by no means a panacea. When designing or specifying a disinfection system, both the lighting designer and the client will need to thoroughly understand the capabilities and limitations of the technology, and agree upon its purpose.

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]]> https://www.allthingslighting.org/visible-light-disinfection/feed/ 0 Quantifying Light Pollution Sources https://www.allthingslighting.org/quantifying-light-pollution-sources/ https://www.allthingslighting.org/quantifying-light-pollution-sources/#respond Thu, 03 Feb 2022 08:02:02 +0000 https://www.allthingslighting.org/?p=2658 time light pollution is sadly familiar to all of us. While our grandparents and great-grandparents may talk fondly of seeing the Milky Way in their youth, with thousands of stars scattered across the dark summer sky, we are mostly content with seeing a few dozen stars through the never-ending dusk of urban and suburban skies.

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]]> https://www.allthingslighting.org/quantifying-light-pollution-sources/feed/ 0 Defining Far-Ultraviolet https://www.allthingslighting.org/defining-far-ultraviolet/ https://www.allthingslighting.org/defining-far-ultraviolet/#respond Fri, 12 Nov 2021 00:00:49 +0000 http://test.allthingslighting.org/?p=2302 In these uncertain times, there is increasingly persuasive evidence that “far-UV” radiation is effective in inactivating the SARS-CoV-2 virus and other pathogens, but without the health risks of germicidal ultraviolet radiation. Unfortunately, this technology has some of the hallmarks of a “miracle cure,” which has become an irresistible attractant for charlatans and hucksters of all […]

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]]> https://www.allthingslighting.org/defining-far-ultraviolet/feed/ 0 Visual Glare and CIE 117-1995 – NEMA White Paper https://www.allthingslighting.org/visual-glare-and-cie-117-1995-nema-white-paper/ https://www.allthingslighting.org/visual-glare-and-cie-117-1995-nema-white-paper/#respond Wed, 13 Oct 2021 00:18:13 +0000 http://test.allthingslighting.org/?p=2308 The CIE Unified Glare Rating (UGR) metric has been use by the architectural lighting industry since it was first published by the CIE a quarter-century ago (CIE 117-1995, Discomfort Glare in Interior Lighting). Originally popularized by European lighting manufacturers, UGR has recently been adopted by the DesignLights Consortium, the US Green Building Council (LEED), and […]

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]]> https://www.allthingslighting.org/visual-glare-and-cie-117-1995-nema-white-paper/feed/ 0 Horticultural Lighting Design and Déjà Vu https://www.allthingslighting.org/horticultural-lighting-design-and-deja-vu/ https://www.allthingslighting.org/horticultural-lighting-design-and-deja-vu/#respond Mon, 13 Sep 2021 00:25:34 +0000 http://test.allthingslighting.org/?p=2316 The phrase déjà vu translates from French as “already seen,” which nicely describes a current issue with horticultural lighting design. The introduction of LED technology may have kick-started horticultural lighting as an innovative industry, but we have yet to learn an important lesson from four decades of architectural lighting. The Importance of Design Data Prior to the […]

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]]> https://www.allthingslighting.org/horticultural-lighting-design-and-deja-vu/feed/ 0 The Effect of Near-Infrared Radiation on Plants https://www.allthingslighting.org/the-effect-of-near-infrared-radiation-on-plants/ https://www.allthingslighting.org/the-effect-of-near-infrared-radiation-on-plants/#respond Mon, 19 Apr 2021 09:00:25 +0000 https://www.allthingslighting.org/?p=1945 Look at any textbook on botany and you will find this maxim: plants respond to optical radiation in the spectral range of 280 nm to 800 nm. Period, end of discussion. The question is, how was this spectral range (sometimes referred to as Photobiologically Active Radiation, or PBAR) determined? This question addresses issues beyond mere […]

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]]> https://www.allthingslighting.org/the-effect-of-near-infrared-radiation-on-plants/feed/ 0 Specifying LED Colors for Horticultural Lighting https://www.allthingslighting.org/specifying-led-colors-for-horticultural-lighting/ https://www.allthingslighting.org/specifying-led-colors-for-horticultural-lighting/#respond Fri, 29 Jan 2021 08:09:02 +0000 https://www.allthingslighting.org/?p=1914 This paper proposes an LED “color” specification that represents a given SPD using a small number of radial basis functions, to provide a metric for comparing biologically similar SPDs. It  further introduces a trainable fuzzy logic SPD classifier that can compare biologically similar SPDs for specific horticultural applications.

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]]> https://www.allthingslighting.org/specifying-led-colors-for-horticultural-lighting/feed/ 0 Ultraviolet Radiation & Viral Misinformation https://www.allthingslighting.org/ultraviolet-radiation-and-viral-misinformation/ https://www.allthingslighting.org/ultraviolet-radiation-and-viral-misinformation/#respond Mon, 04 Jan 2021 04:19:44 +0000 https://www.allthingslighting.org/?p=1907 Let me begin with a smorgasbord of headlines: 99.9% of Covid-19 virus dead in 30 seconds with UV LEDs, says Tel Aviv research (www.malaysianow.com) UV-emitting LED lights found to kill coronavirus (www.sciencedaily.com) Study reveals UV LED lights effectively kill a human coronavirus (www.medicalnewstoday.com) You can kill Covid with a flick of a switch, study shows […]

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]]> https://www.allthingslighting.org/ultraviolet-radiation-and-viral-misinformation/feed/ 0 Ultraviolet Radiation Terminology https://www.allthingslighting.org/ultraviolet-radiation-terminology/ https://www.allthingslighting.org/ultraviolet-radiation-terminology/#respond Mon, 14 Sep 2020 05:03:03 +0000 https://www.allthingslighting.org/?p=1894 A word of caution: I am going to be annoyingly pedantic here, but with good reason. The lighting industry has a century-long history of introducing unfamiliar technologies using familiar terminology. We later come to regret our choice of words when it becomes necessary to express precisely what we mean. Consider, for example, the term luminance. […]

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]]> https://www.allthingslighting.org/ultraviolet-radiation-terminology/feed/ 0 Spherical Irradiance and Aerosols https://www.allthingslighting.org/spherical-irradiance-and-aerosols/ https://www.allthingslighting.org/spherical-irradiance-and-aerosols/#respond Thu, 20 Aug 2020 05:12:29 +0000 https://www.allthingslighting.org/?p=1879 Lighting designers will be familiar with the illuminance of a planar surface, which is measured in lumens per square meter (or foot). The irradiance of a planar surface by a germicidal radiation source is conceptually the same, except that it is measured in watts per square meter (W/m2). Most designers, however, will not be familiar […]

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]]> https://www.allthingslighting.org/spherical-irradiance-and-aerosols/feed/ 0 Defining Photosynthetic Photon Efficacy https://www.allthingslighting.org/defining-photosynthetic-photon-efficacy/ https://www.allthingslighting.org/defining-photosynthetic-photon-efficacy/#respond Fri, 26 Jun 2020 19:39:58 +0000 https://www.allthingslighting.org/?p=1859 There has been some discussion online and in presentations recently about the issue of photosynthetic photon flux. The argument goes as follows: Photosynthetically Active Radiation (PAR) is somewhat arbitrarily defined as optical radiation within the spectral range of 400 nm to 700 nm. Exposing plants to far-red radiation (defined as 700 nm to 800 nm) […]

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]]> https://www.allthingslighting.org/defining-photosynthetic-photon-efficacy/feed/ 0 Designing an Ultraviolet-C Disinfection System https://www.allthingslighting.org/designing-an-ultraviolet-disinfection-system/ https://www.allthingslighting.org/designing-an-ultraviolet-disinfection-system/#respond Tue, 09 Jun 2020 22:59:59 +0000 https://www.allthingslighting.org/?p=1811 Recent germicidal light sources include UV-C light-emitting diodes and pulsed xenon discharge lamps, but there is a newcomer on the block that has gained considerable media attention: far-ultraviolet excimer lamps. What does it take to design a UV-C disinfection system using far-UV radiation?

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]]> https://www.allthingslighting.org/designing-an-ultraviolet-disinfection-system/feed/ 0 Climate-based Annual Daylight Modelling for Greenhouses with Supplemental Electric Lighting https://www.allthingslighting.org/climate-based-annual-daylight-modelling-for-greenhouses-with-supplemental-electric-lighting/ https://www.allthingslighting.org/climate-based-annual-daylight-modelling-for-greenhouses-with-supplemental-electric-lighting/#respond Fri, 22 May 2020 17:26:52 +0000 https://www.allthingslighting.org/?p=1831 Recent advances in LED-based luminaire design have enabled greenhouse operators to temporally control both the photon flux density and spectral irradiance incident upon the plant canopy.

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]]> https://www.allthingslighting.org/climate-based-annual-daylight-modelling-for-greenhouses-with-supplemental-electric-lighting/feed/ 0 Greenhouses and Light Pollution https://www.allthingslighting.org/greenhouses-and-light-pollution/ https://www.allthingslighting.org/greenhouses-and-light-pollution/#respond Wed, 22 Apr 2020 22:09:52 +0000 https://www.allthingslighting.org/?p=1729 Supplemental electric lighting for greenhouses may be essential for extending the growing season in northern climates, but it comes with a not-so-hidden cost: environmental light pollution. The consequences of this pollution may range from irate neighbours in rural areas to municipal bylaws that may prohibit the use of supplemental lighting during certain hours of the […]

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]]> https://www.allthingslighting.org/greenhouses-and-light-pollution/feed/ 0 Ultraviolet Disinfection for Consumers https://www.allthingslighting.org/ultraviolet-disinfection-for-consumers/ https://www.allthingslighting.org/ultraviolet-disinfection-for-consumers/#respond Tue, 21 Apr 2020 23:16:38 +0000 https://www.allthingslighting.org/?p=1716 In these unfortunate times, it seems that everyone is looking for ways to help with the COVID-19 crisis. From a lighting designer’s perspective, one solution is obvious: ultraviolet radiation. We have known about the disinfectant properties of ultraviolet radiation for nearly 150 years (Downes and Blunt 1877), and we have been using low-pressure mercury arc […]

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