Glossary of Outdoor and Indoor Lighting
A Glossary of Lighting Terms and What They Mean
Acanthus Leaf (-Cup, -Frieze): A frequently used post ornament shaped like the thistle-like acanthus plant, usually sitting between the base elements and the slender shaft of a cast post. → Acanthus (ornament).
Acrylic Glass: → PMMA.
Amber Glass: A colloquial term for yellow glass colored with iron oxide, samarium, or indium oxide.
Anodizing: Artificial oxidation for corrosion protection, used for example on aluminum — important for outdoor lights. → Anodizing.
Applique: (in this context) wall light.
Bakelite: An early thermosetting plastic based on phenolic resin, commonly used for sockets. → Bakelite.
Ballast: A device for limiting current when operating gas discharge or fluorescent lamps, available as a separate component or integrated into the bulb, as with many energy-saving lamps.
Baluster: (from the ancient Greek balaustion, meaning pomegranate) usually a round, heavily profiled column section of a cast post. → Baluster.
Barn Light: Shade light, reflector light. → Fixture Types.
Base: The connection between a bulb and its → socket. Bases are described with letter/number combinations — for example, "E" for the standard Edison base, as in E14 or E27.
Beam Angle: The beam angle of a fixture determines the size of the resulting cone of light. While a narrow beam — for example, 15 degrees on fixtures with a deep-drawn shade — concentrates the light very tightly, a wide beam of, say, 70 degrees illuminates a large area and produces softer light.
Brilliance: Brilliance is caused by reflection of the light source or refraction of light, particularly on the curves and edges of glossy objects. The more point-like a light source's emission, the more brilliant it's perceived to be. A negative effect of brilliance is → glare.
Candela: Candela (cd) is the unit of luminous intensity. It measures the light effect produced in the eye by the radiation it receives. → Candela.
Candelabra: A multi-flame post light; (specifically) the fixture arm or post bracket on a multi-flame post light. → Candelabra.
Canopy: The ceiling component or ceiling cap of a ceiling light or pendant light. The canopy conceals the ceiling outlet for the supply cable, and with it any undecorative cable connections and terminal blocks.
Cast Candelabra Arm: A post bracket formerly made from grey cast iron, today usually cast aluminum — see also Candelabra.
Cast Lantern: A lantern formerly made from grey cast iron, today usually cast aluminum; its counterpart is the lantern made from shaped metal (steel, brass, copper, zinc, aluminum).
Cast Post: A lamp post formerly made from grey cast iron, today usually cast aluminum.
CE Marking: With the CE mark (Communauté Européenne), the manufacturer confirms that their product complies with the applicable European directives.
Chromate Conversion Coating: An electrogalvanic process for corrosion protection, used for example on aluminum — important for outdoor lights. → Chromate conversion coating.
Circadian Rhythm: The circadian rhythm refers to the human body's "internal clock." With its light-dark cycle, it spans 24 hours. The effects of insufficient light — low mood, reduced performance, fatigue — can be lessened with the right lighting. → Circadian rhythm.
Color Temperature / Light Color: Color temperature is a measure used to quantify the color impression a light source makes. The unit of color temperature is Kelvin (K). The lower the color temperature, the warmer the light is perceived to be.
Compact Fluorescent Lamps: Especially small fluorescent lamps, colloquially also known as energy-saving lamps. With compact fluorescent lamps, a distinction has to be made between lamps with and without an integrated ballast. Lamps with an integrated ballast usually have a screw base, so they can be used as a direct replacement for incandescent bulbs with an Edison thread.
Cylinder Glass: also known as a glass shade — removable protective glass, as found for example on barn lights.
DALI: DALI (Digital Addressable Lighting Interface) is a manufacturer-independent interface that allows electronic ballasts to be controlled via digital interfaces. This makes it possible to control fixtures individually or in groups — for dimming, switching, and more. → Digital Addressable Lighting Interface.
Diffuser: A glass body or pane, or a light-permeable plastic or metal body, through which the light is scattered.
Dimming: Adjusting the brightness of a fixture. This makes it possible to change the mood of the light, or adapt it to how a room is being used at a given moment.
Electronic Ballast (EVG): Electronic ballasts regulate the current ahead of discharge lamps (e.g., → fluorescent lamps). Besides a flicker-free instant start and flicker-free operation, electronic ballasts have the advantage over conventional ballasts of enabling higher luminous efficacy and a longer service life. → Electrical ballast.
ENEC: The ENEC mark (European Norms Electrical Certification) confirms compliance with European safety standards. It's awarded by independent testing institutes. → ENEC Mark.
Energy Efficiency: Across Europe, lamps are labeled with the so-called energy label. It rates their efficiency from A to G: A stands for especially low consumption (e.g., LED bulbs), G for inefficient bulbs.
EuP (Energy-using Products) Directive: It mandates the phased withdrawal of inefficient products, such as the traditional incandescent bulb. → Ecodesign Directive.
Fluorescent Lamp: A tube- or ring-shaped lamp, or one with a compact coiled shape, coated on the inside with a fluorescent substance and requiring a ballast to operate. Fluorescent lamps are known for their high luminous efficacy and long service life. Their applications include, among others, broad general lighting in commercial settings. → Fluorescent lamp.
Fluting, Flutes, Fluted: (French: cannelure, meaning groove or channel) the vertical, concave grooves carved into a column shaft. → Fluting (architecture).
Glare: Glare reduces visual performance and is perceived as unpleasant. It's caused either by the light source itself (direct glare) or by reflections (reflected glare). To avoid glare, the light source is shielded — for example, with shades and reflectors, baffles, louvers, or satin or opal glass.
Glass Shade, Shade: (removable/screw-off) cylinder glass, as found for example on barn lights.
Guilloche Frieze (Braided-Band Frieze): A column ornament stylizing a braided band.
Illuminance: Illuminance, measured in lux (lx), indicates how much → luminous flux arrives at a given distance from the light source — that is, the ratio of the luminous flux falling on a surface to the size of that surface.
Incandescent Lamp, Incandescent Bulb: The most common type of bulb until the introduction of energy-saving lamps and LED bulbs, though it's disappearing from the market due to insufficient energy efficiency (→ EuP). The color temperature of incandescent bulbs is between 23,000 and 2,900 Kelvin, with an average service life of around 1,000 operating hours.
Ladder Iron, Ladder Bracket: Usually a two- or four-part lantern mounting (bracket) between the lantern cage and the wall arm or post, against which a ladder was once rested to light gas lanterns.
Lantern: A time-tested type of outdoor light. → Fixture Types.
LED: A light-emitting diode (LED) is a semiconductor component that emits light. LEDs are now available in a range of light colors, achieved through colored coatings on the diodes. LEDs are highly energy-efficient and have a long service life. LEDs gradually grow dimmer over time, but as a rule don't fail suddenly. → Light-emitting diode.
Light Color: → Color Temperature.
Light Distribution: The light characteristics of a fixture can be divided into different categories — for instance, a distinction is made between direct, indirect, diffuse, and directional radiation.
Light Source / Bulb: Light sources fall into three categories: thermal radiators (→ incandescent bulbs, → mains-voltage halogen bulbs, → low-voltage halogen bulbs), discharge lamps (→ fluorescent lamps, → compact fluorescent lamps, low-pressure sodium lamps, high-pressure sodium lamps, → metal halide lamps, etc.), and → LEDs.
Low-UV Bulbs: Modern LED bulbs, such as the Pharox LS, that emit only around 10% of the UV light of conventional bulbs. This largely keeps nocturnal insects away from the fixture.
Low-Voltage Halogen Bulb: A → thermal radiator that runs on 12 volts and therefore requires a → transformer. Low-voltage halogen bulbs have an average service life of 2,000 to 5,000 hours and a luminous efficacy of 19 to 35 lumens per watt.
Lumen: The unit of → luminous flux. A 100 W incandescent bulb, for example, produces 1,380 lumens (lm).
Luminance / Luminance Distribution: The impression of brightness, measured in → candela per square meter. The human eye perceives differences in luminance as differences in brightness. Balanced luminance ratios are especially important in the workplace. Gloss properties, reflectance, and colors should be chosen so as to avoid excessive luminance differences.
Luminous Efficacy: Luminous efficacy expresses how efficient a light source is. It's measured in lumens per watt (lm/W). → Luminous efficacy.
Luminous Flux: Luminous flux represents the total radiant power emitted by a light source. It's given in lumens (lm). → Luminous flux.
Luminous Intensity: The portion of the luminous flux radiating in a specific direction, measured in → candela. The so-called light distribution curve represents this distribution graphically, in the form of a curve.
Mains-Voltage Halogen Bulb: As the incandescent bulb has gradually disappeared, mains-voltage halogen bulbs have increasingly been used as an alternative, since they have very similar properties to incandescent bulbs and run on 230 volts (no transformer needed). As so-called thermal radiators, they're less efficient than → compact fluorescent lamps or → LEDs, but they're known for a color temperature that's perceived as pleasant. Their service life is around 2,000 to 4,000 hours.
Metal Halide Lamp: Metal halide lamps stand out for their long service life, high luminous efficacy, and excellent color rendering. Before LED bulbs appeared, metal halide lamps and sodium vapor lamps were among the most efficient light sources. Because of the properties described above, they're often used in commercial settings.
Old German Glass: (the official designation is "Altdeutsch K Weiss.") Clear glass given air bubbles and a slightly textured surface during the rolling process, using a wet wooden lath. Also known as: antique glass.
OLED: A technology still in the development phase for use in fixtures, in which a light-emitting thin-film component made of organic semiconducting materials serves as the light source. OLEDs (organic light-emitting diodes) are currently of particular interest for use as flexible displays or electronic paper.
Opal Glass: Glass made opaque with the opacifying agent cryolite (sodium hexafluoroaluminate, formula Na₃AlF₆). Also known as cryolite glass, it appears milky white — light-permeable, but not transparent. The opacity results from tiny particles evenly distributed within the colorless base glass; these particles have a different refractive index than the base glass.
Patina, Patinated: A (artificially) aged surface (weathering layer) on brass, silver, gold, and copper (see Verdigris); in a broader sense, also used for aluminum, zinc, and other metals (where the more accurate term is actually "pre-weathered"). → also Materials for Outdoor Lights.
Plafoniera, Plafoniere: A (flat) ceiling light.
PMMA: Polymethyl methacrylate, also known as acrylic glass, is a synthetic, glass-like thermoplastic. → also Materials for Outdoor Lights.
Polycarbonates: Synthetic, glass-like polymers from the polyester family. → also Materials for Outdoor Lights.
Powder Coatings, Polyester Powder Coating: An extremely weather-resistant, solvent-free coating technology, ideal for outdoor lights.
Pre-Weathered: A surface (weathering layer) made to look old using chemical agents, on wood, stone, and metals. With brass, silver, gold, and copper, this is also referred to as patina.
Radiation Pattern (Light Distribution): Different types of fixtures, barn lights especially, emit their light across different angular ranges; the shape of the fixture or its shade (symmetric or asymmetric) also influences the light distribution. The radiation pattern of some fixtures can be adjusted as needed using reflectors, lenses, and louvers.
Reflector: The shade (or lower part of the shade), or the usually white or silver-colored back panel or top inside a lantern.
Satin Glass (Frosted Glass): Clear glass made matte through etching or sandblasting, rendering it largely opaque.
Shielding Angle (Cutoff Angle): The angle between the room ceiling and the light source's beam area. A relatively wide shielding angle of, say, 25 degrees produces a large cone of light and an even distribution of light in the room (general/ambient lighting, e.g., from a ceiling light), while a shielding angle of, say, 60 degrees focuses the light more tightly on an object (task lighting on a table or desk).
Socket: The socket holds the bulb in place in the fixture. Especially with halogen bulbs, there's a huge range of different sockets, but for halogen bulbs, energy-saving lamps, and LED bulbs, the tried-and-tested Edison screw sockets E14 and E27 are still the most common.
Transformer: Transformers are used to step electrical AC voltage up or down. They're needed, for example, to convert the 230-volt mains voltage into the low voltage required for 12-volt low-voltage halogen bulbs.
Verdigris (= Copper Acetate): A colloquial, but technically incorrect, term for the greenish copper patina — actually a mixture of copper carbonate, sulfate, chloride, and hydroxide compounds. On modern copper alloys, green copper patina now usually only forms under the action of acid or urea on copper. → Copper(II) acetate.
