MJBizMagazine September 2021 Lighting Buyers Guide - 17

MJBizDaily Buyers Guide Lighting
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Fixture Efficacy-The energy efficiency of a fixture, or how much output is generated per unit of energy
and how efficient a fixture is at converting energy into photosynthetic light. Fixture efficacy is especially
important for indoor lighting.
HID-High-intensity discharge (HID) lights produce light by creating an arc of electricity between two
electrodes housed inside a tube filled with a noble gas. They produce much more light per watt than
incandescent or fluorescent bulbs. HPS and metal halide lights are types of HID lights traditionally used in
horticultural lighting.
HPS-High-pressure sodium (HPS) lamps are high-intensity light bulbs filled with sodium that produce large
amounts of light and heat energy. HPS lamps had been the industry standard for horticultural (and cannabis)
lighting until the advent of LEDs (see below). They generally produce a red or yellowish light.
Joule-A unit of energy (J). The amount of electricity required to light one watt for one second.
LED-Light-emitting diode (LED) lights are much more energy efficient at producing high intensity than
HPS lamps, and can produce light in many more spectrums. However, LED fixtures are variable in their
optimization for spectrum and light intensity based on manufacturer and are typically much more expensive
to buy initially.
Light Quality-Describes the colors of the light
or the spectrum of the light, for example, how much blue, green, red or other light spectrums are
emitted from a light source. Not all are visible to the
human eye.
Light Quantity-Refers to the intensity or the brightness of the light and is the number of photons
produced. Light quantity may be measured as the instantaneous amount of light (PAR) produced or the
cumulative amount delivered in a day (DLI).
Lighting Uniformity-How evenly light is distributed to a growing area, including uniformity of light
spectrum and intensity. Because lighting regulates plant growth, flowering and water consumption, the
uniformity of the lighting impacts the uniformity of the crop.
Metal Halide Light-An HID light with metal halide as the gas inside the bulb. Metal halide lamps give off a
whiter/bluer light than HPS lamps and were traditionally used by growers in the vegetative stage of growth.
Micromoles (µmol)-Unit used to measure how bright the light is. One mole equals 1,000,000
micromoles. Growers use micromoles to measure the PPFD, a measure of the number of actual photons
emitted over a square meter per second-expressed as µmol of photons mmeasurement
(or DLI) is an expression of moles of light per square meter per day.
² s-¹ of PAR. A daily mole
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MJBizMagazine September 2021 Lighting Buyers Guide

Table of Contents for the Digital Edition of MJBizMagazine September 2021 Lighting Buyers Guide