Can Designs and Measurements Based on the Circadian Stimulus Model Stand the Test of Time?
Authors: 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...
Specifying LED Colors for Horticultural Lighting
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.
Ultraviolet Radiation & Viral Misinformation
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...
Ultraviolet Radiation Terminology
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...
Spherical Irradiance and Aerosols
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...
Defining Photosynthetic Photon Efficacy
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...
Designing an Ultraviolet-C Disinfection System
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?
Climate-based Annual Daylight Modelling for Greenhouses with Supplemental Electric Lighting
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.
Greenhouses and Light Pollution
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...
Ultraviolet Disinfection for Consumers
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...