Light Stack • Knockout Lighting Design Inc.

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ANSI (American National Standards Institute): A private non-profit organization that oversees the development of voluntary consensus standards for products, services, processes, systems, and personnel in the United States, including standards for lighting equipment and practices.

Accent Beam Spread: Describes the width of light emitted from an accent lighting source, crucial for highlighting specific features or objects within a space.

Accent Luminaire: A light fixture specifically designed to direct light and focus attention on a particular area or object. These luminaires are used for accent lighting purposes, to highlight architectural features, artwork, or merchandise in retail settings.

Acoustic Lighting: Lighting fixtures designed with materials or features that help reduce noise, combining illumination and sound management in environments like offices or restaurants.

Adapter: A device used to fit lighting fixtures into sockets or mounts not originally designed for them, allowing for greater flexibility in lighting design.

Adaptive Lighting: Lighting that automatically adjusts its output or color temperature in response to various factors, such as the presence or absence of natural light, the time of day, or occupancy levels. This adaptability improves energy efficiency and user comfort.

Aging Effects on Luminaires: The impact of time and environmental factors on the performance and appearance of lighting fixtures, including changes in light output and color.

Albedo Effect in Lighting Design: Refers to the reflectivity of surfaces in an environment, which can significantly affect the brightness and distribution of light, both natural and artificial.

Alternating Current (AC): The type of electrical current used to power most homes and buildings. In AC, the flow of electric charge periodically reverses direction. Lighting fixtures designed for AC power must be compatible with the frequency and voltage of the local electrical supply.

Alternating Current (AC) Driver: A device that converts AC power from the mains to a form usable by some lighting fixtures, especially LED lights.

Ambiance Lighting: Similar to ambient lighting, ambiance lighting focuses on creating a specific mood or atmosphere in a space. It involves the strategic use of light levels, colors, and distributions to evoke particular feelings or emotions, enhancing the aesthetic appeal of an environment.

Ambient Glare Control: Strategies and designs implemented in lighting to minimize glare and ensure a comfortable visual environment, especially important in workspaces and public areas.

Ambient Light Override: A feature in lighting control systems that prevents lights from turning on automatically when sufficient natural light is present, to conserve energy.

Ambient Light Sensor: A device that measures the level of natural light in an environment. It is often used in automated lighting systems to adjust artificial lighting levels in response to changes in natural daylight, enhancing energy savings and maintaining consistent lighting conditions.

Ambient Light Sensor: A device used in lighting systems to detect the level of natural light in an environment and adjust artificial lighting accordingly to maintain a desired level of illumination.

Ambient Lighting: The primary source of light in a space, providing overall illumination to ensure a comfortable level of brightness without causing glare. It creates a uniform light level across an area, often achieved through ceiling fixtures, recessed lights, or wall-mounted fixtures.

Ambient Luminaire: A lighting fixture that provides general, overall illumination to an area. Ambient luminaires are designed to produce a uniform light level throughout a space, enhancing visibility and comfort without creating harsh shadows or glare.

Ambient Occlusion: A shading method used in lighting design to give a more realistic feel to the environment by simulating how light radiates in real life, especially in confined spaces.

Ampere-Hour (Ah): A unit of electric charge representing the amount of charge transferred by a steady current of one ampere flowing for one hour. In lighting, especially in the context of battery-operated or emergency lighting, the ampere-hour rating of a battery indicates its capacity to power a fixture for a specified duration.

Amperes (Amps): The unit of measure for electrical current. In lighting, it is important to consider the current draw of fixtures to ensure that electrical systems are not overloaded.

Analog Dimming: A dimming method for lighting fixtures that adjusts the light output by varying the voltage supplied to the lamp, as opposed to digital or PWM (Pulse Width Modulation) dimming.

Anchor Light: A specific type of lighting used in maritime contexts, usually on boats or ships, to signal the vessel’s presence when anchored at night.

Aperture: The opening in a lighting fixture through which light is emitted, whose size and shape can affect the distribution and quality of light.

Architectural Dimming: A dimming technique that integrates seamlessly with architectural elements, often involving sophisticated control systems for ambiance and energy savings.

Architectural Sconce: A wall-mounted lighting fixture that provides both functional and decorative light, often used in corridors, living spaces, and outdoor areas to complement architectural styles.

Articulated Luminaire: A light fixture designed with joints or sections that can be adjusted or moved to change the direction or focus of the light output.

Artificial Skylight: Advanced lighting technology that mimics the appearance and lighting effect of a natural skylight, used in interior spaces lacking direct access to daylight.

Asymmetric Reflectors: Reflectors designed to redirect light in a non-uniform pattern, often used in fixtures aimed at illuminating walls or specific areas unevenly.

Asymmetrical Lighting Distribution: A lighting distribution pattern where the intensity of light varies in different directions. This type is often used in wall washing or when lighting needs to be focused more on one side of a space than the other, providing an uneven spread of light tailored to specific requirements.

Automated Lighting Control Systems: Systems designed to automatically adjust the output of lighting based on various factors such as time of day, occupancy, or natural light levels. These systems can include dimmers, motion sensors, daylight sensors, and timers to optimize energy efficiency and user comfort.

Average Illuminance: The average amount of light (measured in lux or foot-candles) falling on a surface. It is calculated by dividing the total luminous flux reaching the surface by the area of the surface. This measurement is used to ensure that lighting meets specified standards for visibility and safety in different settings.

Axial Luminance: The measure of brightness along the axis from the light source, important in the design of direct lighting schemes and in assessing glare.

Backlighting: A technique that illuminates the subject from behind, creating a silhouette or highlighting edges. In architectural lighting, it can accentuate textures or architectural features.

Backlit Panels: Lighting fixtures that illuminate from behind a diffuser or panel, creating a uniform and soft light ideal for ambient lighting in commercial and residential spaces.

Baffle: A component of a lighting fixture used to reduce glare by controlling the direction of light output, often found in recessed lighting.

Barn Doors: Adjustable attachments for light fixtures, particularly spotlights and floodlights, used to control the spread and direction of the light beam.

Baseline Lighting Load: The minimum amount of lighting needed to meet the basic requirements of a space, often determined by building codes or by the specific needs of the occupants.

Bath Bar Lighting: A lighting fixture designed to be mounted above or alongside mirrors, particularly in bathrooms, to provide even, shadow-free illumination across the face and surrounding area.

Beam Efficacy: A measure of how effectively a light source produces visible light, expressed in lumens per watt (lm/W). It indicates the efficiency of a light source in converting electrical energy to visible light.

Beam Spread: The area over which a light source distributes significant illumination, typically measured at the points where the intensity falls to a certain percentage of the maximum, such as 50%.

Bespoke Lighting: Custom-designed lighting fixtures or systems tailored to meet the specific requirements of a project or space. These solutions are often used in high-end design projects where off-the-shelf products do not suffice.

Binary Switching: A control strategy for lighting systems where lights are either fully on or fully off, with no dimming capabilities. This is a basic form of lighting control used in many commercial and residential applications.

Binning: The process of categorizing LED chips based on their color, voltage, and brightness characteristics to ensure consistency in lighting products.

Biodynamic Lighting: Also known as human-centric or circadian lighting, it adjusts color temperature and intensity throughout the day to mimic natural daylight patterns, supporting human circadian rhythms.

Biophilic Lighting Design: An approach to lighting that seeks to connect occupants more closely to nature through the use of natural light, lighting systems that mimic natural light, and elements that reflect the natural environment.

Blackbody Radiator: In lighting, a theoretical object that absorbs all incident light and emits radiation at a characteristic spectrum. The color temperature of light sources is often compared to that of a blackbody.

Blackout Control: Lighting systems or devices designed to achieve complete darkness in a space, often used in theaters, media rooms, and other areas where controlling light exposure is critical.

Blind Spot Illumination: Lighting designed to illuminate areas that are typically not covered by standard lighting fixtures, often used in security and safety applications to cover areas that would otherwise be hidden from view.

Blue Light Hazard: Refers to the potential harm to the eye from exposure to high-intensity blue light, particularly from LED sources. Lighting design considers minimizing this risk, especially in environments where people spend significant amounts of time.

Bluetooth Mesh Networking: A technology used in smart lighting systems allowing fixtures to communicate with each other over Bluetooth, facilitating wireless control and automation.

Bollard: A short, vertical post light that illuminates walkways, paths, or landscaping features. Bollards are commonly used in outdoor public spaces for safety, security, and aesthetic purposes.

Bounce Lighting: A technique where light is directed towards a surface or object and reflected onto the subject, producing a diffuse and soft illumination. It’s often used in photography, film, and interior design to create a natural-looking light.

Brightness Control: Techniques or devices used to adjust the brightness level of a lighting fixture, including dimmers and smart lighting controls, to enhance comfort or conserve energy.

Bug Rating: A system (Backlight, Uplight, and Glare) for evaluating outdoor lighting fixtures based on their light trespass, sky glow, and glare contributions, helping to minimize light pollution.

Building Automation System (BAS) for Lighting: Integrated systems that control lighting as part of a building’s overall automation system, optimizing energy use and enhancing occupant comfort.

Bulkhead: Robust, sealed lighting fixtures designed for outdoor use or in wet environments, commonly mounted on walls or ceilings to illuminate walkways, tunnels, and utility spaces.

CRI R9: A specific measure within the Color Rendering Index that indicates how well a light source renders deep red colors compared to an ideal or natural light source. It’s particularly important in settings where accurate color representation of red tones is critical.

Candela (cd): The SI unit of luminous intensity, describing the amount of light emitted by a source in a particular direction. It is a critical measurement in understanding how bright a light source will appear from a specific viewpoint.

Candlepower Distribution: A graphical representation that shows how the luminous intensity of a light source varies with direction, crucial for understanding the spread and directionality of light from fixtures.

Ceiling Bounce: A lighting technique where light is directed upward towards a ceiling and reflected back down to illuminate a space. This indirect lighting method helps to reduce shadows and glare, creating a uniform light distribution.

Chromacity: A measure of color that includes hue and saturation but not brightness. In lighting, it’s used to describe the specific color characteristics of a light source apart from its intensity or lightness.

Chromaticity: A description of the quality of color, regardless of its luminance, that includes hue and saturation. It is often represented in a chromaticity diagram that provides a visual representation of color characteristics.

Circuit Load: The total amount of power consumed by devices on a circuit. Understanding circuit load is important in lighting design to ensure that electrical systems are not overloaded, which can lead to circuit breaker trips or electrical fires.

Clerestory Lighting: High windows or a series of windows above eye level, allowing natural light to penetrate deep into interior spaces, enhancing daylighting and reducing the need for artificial light.

Color Rendering Index (CRI): A measure (on a scale from 0 to 100) of the ability of a light source to reveal the colors of various objects faithfully in comparison with an ideal or natural light source. Higher CRI values indicate that colors under the light source appear more accurately.

Color Temperature: Measured in Kelvins (K), it describes the color appearance of the light emitted by a source, ranging from warm (lower Kelvin numbers, e.g., 2700K) to cool (higher Kelvin numbers, e.g., 6500K). It affects the mood and visual comfort of a space.

Compact Fluorescent Lamp (CFL): A type of fluorescent lamp designed to replace an incandescent lamp; it uses a compact electronic ballast in the base of the lamp to control the current through the fluorescent tube, making it more energy-efficient.

Conductor: A material that allows the flow of electrical current in one or more directions. In lighting, conductors are essential for connecting the power source to the lighting fixtures.

Contrast Ratio: The ratio of the luminance of the brightest color (white) to that of the darkest color (black) that the system is capable of producing. A high contrast ratio is a desirable aspect of any display system, as it means better picture quality.

Cool White: A term used to describe LED and fluorescent lamps that emit a bright, neutral to slightly blue light, typically with a color temperature of 4000K to 5000K, ideal for task lighting and areas requiring focus.

Correlated Color Temperature (CCT): A specification of the color appearance of the light emitted by a lamp, relating its color to the color of light from a reference source when heated to a particular temperature, measured in Kelvins (K).

Cosine Law: A principle stating that the illuminance (or light level) on a surface is proportional to the cosine of the angle of incidence of the light hitting the surface. This law is crucial in calculating and designing effective lighting layouts.

Coupler: A device used in lighting systems to connect sections of track lighting or to join other lighting components together, ensuring a secure electrical and mechanical connection.

Cove Cut-off: A design feature in cove lighting that ensures the light source itself is not visible from normal viewing angles, enhancing the aesthetic appeal by hiding the fixtures while providing a soft, diffused light.

Cove Lighting: A form of indirect lighting built into ledges, recesses, or valances in a ceiling or high on the walls of a room. It is used to add ambient lighting or decorative accents to a room.

Cross-fading: In lighting design, particularly for theatrical and entertainment lighting, the gradual dimming of one set of lights while simultaneously increasing the intensity of another, creating a seamless transition between scenes or effects.

Current Regulator: A device or circuitry within a lighting system that maintains a constant electrical current through a LED, ensuring stable light output and prolonging the lifespan of the LEDs.

Cutoff Angle: In lighting fixtures, the angle measured from the vertical at which the lamp is not visible, and direct glare is minimized. It is essential for controlling glare in lighting installations.

Cutoff Fixture: A luminaire designed to direct the light downward with little to no light spill above the horizontal plane, reducing glare and light pollution. These are often used in outdoor lighting applications.

Cyanosis Observation Index (COI): A measure used to evaluate the ability of a light source to accurately reveal the coloration of human skin, particularly in medical and healthcare settings, for the observation of cyanosis or other skin color changes.

DALI (Digital Addressable Lighting Interface): A protocol for digital communication between lighting control devices. DALI is used for more precise and efficient control over lighting systems, allowing for individual lights to be controlled separately.

DMX (Digital Multiplex): A communication protocol used in stage lighting and effects that enables control over individual lighting fixtures, dimmers, and special effects devices.

Daisy Chain: A wiring scheme where multiple lighting fixtures or devices are connected in series or parallel within a single circuit, allowing for simplified installation and centralized control.

Dark Sky Compliance: Lighting fixtures and practices designed to minimize light pollution, skyglow, and glare, thereby preserving the natural night sky environment.

Daylight Factor: A metric that measures the amount of daylight available in an interior space compared to the natural light available outdoors, used in sustainable building design to maximize natural light usage.

Daylight Harvesting: The use of control systems and sensors to adjust indoor lighting based on the amount of natural daylight in a space, thereby reducing energy consumption and enhancing occupant comfort.

Daylight Sensors: Devices that detect natural light levels and automatically adjust artificial lighting accordingly, part of daylight harvesting systems to optimize energy use and enhance indoor environmental quality.

Daylighting: The practice of placing windows or other openings and reflective surfaces so that during the day natural light provides effective internal lighting. Daylighting strategies are critical for reducing energy consumption by minimizing the need for artificial lighting.

Daylighting Design: The art and science of designing buildings and spaces to maximize the use of natural light, reducing the need for artificial lighting and improving energy efficiency and occupant well-being.

Decorative Filament Bulbs: Light bulbs designed with visible filaments, often in LED form to mimic the look of vintage incandescent bulbs, used for their aesthetic appeal in exposed bulb fixtures or as standalone decorative elements.

Decorative Lighting: Lighting that serves an aesthetic purpose in addition to providing illumination, often featuring unique designs, shapes, and colors to complement the decor of a space.

Degradation, Luminous: The gradual decrease in light output of a lighting source over time, a common phenomenon in LEDs and other light sources, which is important to consider in long-term lighting planning and maintenance.

Design Lumens: The initial lumen output of a lighting fixture adjusted for expected depreciation over time, used in lighting design calculations to ensure adequate illumination throughout the lifespan of the lighting system.

Dichroic Lamp: A lamp with a dichroic coating that reflects certain colors of light while allowing others to pass through, used in applications where precise color control is desired, such as in display lighting.

Diffuse Lighting: Lighting that spreads light evenly with soft shadows, reducing glare and creating a gentle illumination that is easy on the eyes, often achieved through the use of diffusers or reflective surfaces.

Diffuse Reflection: The scattering of light in many directions from a rough or matte surface, as opposed to specular reflection from a shiny surface, resulting in soft, even lighting.

Diffuser: A device used to spread the light from a light source evenly in a space, reducing glare and softening shadows. It can be made of glass, plastic, or fabric and is commonly used in both residential and commercial lighting fixtures.

Dim-to-Warm: A feature in some LED lighting that mimics the color temperature shift of incandescent bulbs as they are dimmed, moving from cooler to warmer light as the intensity decreases, creating a cozy atmosphere.

Dimmable LED: An LED light source that can be dimmed to lower light levels, offering flexibility in adjusting room ambiance and conserving energy.

Dimmer: A device that allows the user to adjust the brightness of a light source. Dimmers can extend the life of the bulb and save energy, while also allowing for the adjustment of lighting levels to suit different activities or moods.

Dimmer Switch: A switch that allows for the adjustment of light intensity of a lighting fixture, enabling control over the ambiance of a space.

Direct Lighting: Lighting where the majority of the light goes directly from the fixture to the area being illuminated, providing clear, bright light for tasks or emphasis.

Direct/Indirect Lighting: A lighting strategy that combines direct lighting (light directed downward for task illumination) with indirect lighting (light directed upward or sideways, reflecting off surfaces to provide ambient illumination), creating a balanced and comfortable lighting environment.

Discharge Lamp: A type of lamp that generates light by passing an electric current through a gas or vapor, including fluorescent, metal halide, and sodium vapor lamps, known for their efficiency and long life but requiring time to reach full brightness.

Disco Ball Effect: A playful, decorative lighting effect achieved by reflecting beams of light off a mirrored ball, creating a dynamic pattern of light spots across a room.

Distribution Pattern: The spatial distribution of light from a fixture, indicating how light is spread over a surface or area.

Dome Light: A type of ceiling light fixture that features a dome-shaped diffuser, often used for general ambient lighting in residential and commercial spaces due to its even light distribution.

Downlight Chandelier: A type of chandelier that focuses light downward, typically used over tables or counters where task lighting is needed along with decorative lighting.

Driver: In LED lighting, a device that regulates power to an LED or a string of LEDs, providing a constant current for optimal performance.

Dropped Ceiling Lighting: Lighting fixtures designed to be integrated into a dropped ceiling system, flush with the ceiling panels or tiles, for a seamless and unobtrusive appearance.

Dusk-to-Dawn Sensor: A sensor that controls outdoor lighting fixtures, turning them on at dusk and off at dawn, optimizing energy usage and providing security lighting.

Dynamic Lighting: Lighting systems that can change in intensity, color temperature, or color to adapt to specific tasks, moods, or times of day, enhancing functionality and atmosphere.

Dynamic White Lighting: Lighting systems capable of adjusting the color temperature of white light from warm to cool shades, simulating the natural progression of daylight throughout the day.

Eave Mount Lighting: Lighting fixtures specifically designed to be mounted under the eaves of a house or building, typically used for outdoor illumination around the perimeter for both aesthetic and security purposes.

Economy Mode: A feature found in some lighting systems that reduces power consumption and output, extending the lifespan of the lighting source and saving energy. This mode is particularly useful in areas where full brightness is not always necessary.

Edge Lighting: A technique where LED strips or other light sources are placed around the perimeter of an object or panel, such as glass, to create a glowing effect. It’s often used in signage, shelves, and decorative panels.

Edge-lit LED Panel: A flat panel light source where LEDs are placed along the edges of the panel. Light is then diffused across the surface by a special material, offering a slim profile and even light distribution ideal for office spaces, retail, and modern interiors.

Efficacy: The efficiency of a light source measured in lumens per watt (lm/W). It indicates the amount of light produced per unit of power consumed. Higher efficacy values mean more efficient light sources.

Egress Lighting: Similar to emergency egress lighting, it specifically refers to lighting installed along pathways leading out of a building or space, ensuring visibility and safety during evacuations.

Electrical Discharge Lamp: A category of light sources, including fluorescent, neon, and HID lamps, that produce light through an electrical discharge through a gas or vapor. These lamps are known for their efficiency and long life but require a warm-up period.

Electroluminescent (EL) Wire: A thin copper wire coated in a phosphor material that emits light when an alternating current is applied. EL wire is flexible, energy-efficient, and used for decorative lighting, costumes, and safety apparel.

Ellipsoidal Reflector Spotlight (ERS): A type of theater light that produces a focused beam of light, often used to highlight specific stage areas or as a follow spot. It features an ellipsoidal reflector and adjustable focus.

Elliptical Reflector: A type of reflector used in lighting fixtures to focus or direct light in a specific pattern. Its elliptical shape allows for more precise control over the direction and spread of light compared to spherical or parabolic reflectors.

Embedded Lighting: Lighting integrated into architectural elements or furnishings, such as floors, walls, or furniture, creating a seamless and innovative lighting effect.

Emergency Backup Battery: An integral component of emergency lighting fixtures, providing power to the fixture during a power outage to ensure continuous operation for safety and egress purposes.

Emergency Egress Lighting: Specialized lighting that illuminates pathways to exits in the event of an emergency, ensuring that occupants can safely evacuate a building.

Emergency Lighting: Lighting systems designed to operate when the main power supply fails, providing illumination for safe exit in emergencies. These systems are crucial in commercial and public buildings for compliance with safety codes.

Emission Spectrum: The spectrum of wavelengths emitted by a light source. Understanding a light source’s emission spectrum is essential for applications requiring precise color rendering and light quality, such as art galleries and medical facilities.

Encapsulated LED: LEDs that are encapsulated or coated in a protective material, often silicone or epoxy, to safeguard against moisture, dust, and physical impact. This process enhances the durability and lifespan of LED lighting in harsh or outdoor environments.

Energy Consumption: The amount of electrical energy used by a lighting system. Reducing energy consumption through efficient lighting design and technology is a key goal in sustainable building practices.

Energy Star: A program run by the U.S. Environmental Protection Agency and the U.S. Department of Energy that certifies lighting and other products for energy efficiency. Energy Star-rated lighting products meet strict efficiency guidelines.

Enhanced Spectrum Bulbs: Light bulbs designed to provide a spectrum of light closer to natural sunlight, improving color rendering and potentially benefiting health by supporting circadian rhythms.

Envelope: In lighting design, the envelope refers to the total space or area that light needs to cover. Understanding the envelope is crucial for planning the layout and intensity of lighting fixtures.

Environmental Impact Rating: An assessment of a lighting product or system’s impact on the environment, considering factors such as energy consumption, materials used, and recyclability.

Environmental Lighting: Lighting that considers the impact on the environment, including energy consumption, light pollution, and the use of sustainable materials and practices.

Epitaxial Growth: In the context of LED manufacturing, it refers to the process of growing crystalline layers on a semiconductor wafer. This process is crucial for creating high-quality LED light sources with efficient light emission.

Ergonomic Lighting: Lighting designed with human health and productivity in mind, addressing factors such as brightness, color temperature, and distribution to create comfortable environments for work and living.

Etched Glass: Glass that has been treated with an acidic, caustic, or abrasive substance to create a frosted appearance. In lighting, etched glass diffusers help distribute light evenly while reducing glare.

Exit Lights: Illuminated signs that indicate the exit routes in buildings, essential for safety and required by building codes in public and commercial spaces.

Exposed Filament Bulbs: Light bulbs, often LED, designed to mimic the look of early 20th-century Edison bulbs with visible, glowing filaments. These bulbs combine the energy efficiency of LED technology with vintage aesthetics.

Exterior Lighting: Lighting that is designed for outdoor spaces. This can include street lighting, garden lighting, facade lighting, and lighting for other outdoor areas. Exterior lighting is important for safety, security, and enhancing the aesthetics of outdoor spaces.

Extruded Aluminum: A common material used in the construction of lighting fixtures, particularly for outdoor and industrial applications, known for its durability, heat dissipation properties, and sleek appearance.

Eye Adaptation: The ability of the eye to adjust to changes in light levels, allowing humans to see in a wide range of lighting conditions. Lighting design takes into account eye adaptation to ensure that transitions between different light levels are comfortable for occupants.

Eye Comfort Lighting: Lighting designed to reduce eye strain and discomfort, often featuring adjustable brightness, minimal glare, and optimal color temperature for reading or task lighting.

F-Number: In architectural lighting, this refers to the ratio of the luminaire’s distance from the surface it’s lighting to the diameter of the light beam. It helps in calculating the spread and intensity of light over a given area.

Facade Lighting: Architectural lighting that focuses on the exterior surface of a building, used to highlight architectural features, provide security, and enhance the building’s appearance during nighttime hours.

Fiber Optic Lighting: A technology that uses optical fibers to transmit light from a light source to a remote location, offering unique decorative effects and applications in areas where conventional lighting would be impractical or hazardous.

Field Angle: The angle between the directions on opposite sides of a luminaire axis where the intensity drops to 10% of the maximum. It provides a broader measure of light spread than the beam angle.

Filament LED Bulbs: LED bulbs designed to mimic the appearance of traditional incandescent bulbs, with LED strips arranged in a way that resembles the filaments of incandescent lamps, offering energy efficiency with a classic look.

Fixture: The assembly that houses the lamp in a lighting system. It includes the components required to fix the lamp in place, protect it, and connect it to the power supply. Fixtures are designed to support the efficient distribution, filtering, and use of the light emitted from the lamp.

Fixture Efficacy: A measure of how efficiently a lighting fixture produces visible light, expressed in lumens per watt (lm/W). It considers both the efficiency of the light source itself and how well the fixture design delivers light to the intended area.

Fixture Lumens: The total lumens emitted by a lighting fixture, accounting for losses due to the design of the fixture. It differs from the lamp lumens, which is the raw output of the light source itself.

Flicker: The rapid variation in light output that can occur in some lighting systems, particularly noticeable in fluorescent and LED lighting without proper drivers or dimmers. Flicker can cause discomfort or health issues for sensitive individuals.

Flicker Index: A quantitative measure of the cyclic variation in the output of a light source, indicating the risk of noticeable flicker. A lower flicker index means less potential for flicker to be observed.

Floodlight: A broad-beamed, high-intensity artificial light used to illuminate outdoor areas or large spaces. Floodlights can highlight architectural features, landscapes, or provide security lighting.

Fluorescent Dimming: The ability to control the light output of fluorescent lamps, typically through the use of special dimming ballasts and controls. It allows for energy savings and the adjustment of lighting levels to suit user preferences or activities.

Fluorescent Lamp: A type of lighting device that uses electricity to excite mercury vapor, which in turn produces short-wave ultraviolet light that then causes a phosphor to fluoresce, producing visible light. Fluorescent lamps are more energy-efficient than incandescent bulbs but contain mercury, which requires careful disposal.

Flux: The total amount of light emitted by a source, measured in lumens (lm). It’s an important measure of a light source’s total light output.

Flux Bin: A categorization of LEDs based on their luminous flux or light output. Manufacturers use flux bins to ensure consistency in the brightness of LEDs used in lighting products.

Foot-candle (fc): A unit of illuminance or light intensity widely used in the United States, representing the light level on a surface one foot from a standard candle. One foot-candle equals approximately 10.764 lux.

Foot-lambert (fL): A unit of luminance or brightness perceived by the human eye, commonly used in the cinema and television industry to describe screen brightness. One foot-lambert equals 1/π candela per square foot.

Footprint: In lighting, this refers to the area illuminated by a light source or fixture. Understanding the footprint is essential for effective lighting design, ensuring adequate coverage and uniformity.

Form Factor: Refers to the size, shape, and physical design of a lighting fixture, important for aesthetic considerations and how the fixture integrates into a space.

Fresnel Lens (fruh·nel lenz): A type of compact lens originally developed for lighthouses, now used in stage and studio lighting to focus light into a narrow beam. It is lightweight and can produce a wide range of beam angles.

Frosted Lens: A lens with a frosted finish that diffuses light, reducing glare and softening the appearance of the light source. It’s used in both residential and commercial lighting fixtures.

Frosting: A process applied to light bulbs or fixtures to diffuse the light they emit, reducing glare and softening the light. Frosted glass or coatings scatter light evenly, creating a softer illumination.

Full Cut-off Fixture: A lighting fixture designed so that all emitted light is directed downward, with no light emitted above the horizontal plane. This design minimizes light pollution and sky glow.

Full Spectrum Lighting: Lighting that covers a broad range of wavelengths from the visible spectrum, simulating natural daylight. It’s believed to have benefits for health and well-being by more closely mimicking the light from the sun.

Functional Lighting: Lighting designed primarily for visibility and to facilitate the performance of tasks or activities, as opposed to decorative or mood lighting.

Gallery Lighting: Specialized lighting designed to showcase artwork and museum exhibits. It often involves adjustable, focused lighting that enhances the visual impact of the art while minimizing damage from light exposure.

Gel: A transparent colored material used over lights to alter the color and quality of the light output. Gels can be used for artistic effects in theatrical, photography, and architectural lighting.

General Illumination: Lighting designed to provide a uniform level of illumination across an area, as opposed to task or accent lighting. It ensures sufficient visibility and comfort for general activities.

General Lighting: Another term for ambient lighting, which provides a uniform level of illumination throughout an area, without emphasis on any particular object or area.

General Service Lamp (GSL): A term often used to describe standard, widely-used light bulbs, including incandescent, compact fluorescent (CFL), and LED lamps, that are suitable for a variety of residential and commercial applications.

Geometric Lighting: Lighting design that emphasizes geometric shapes or patterns, either through the arrangement of fixtures or the shape of the light itself. It can add a dramatic or structured visual element to a space.

Gesture Control Lighting: Lighting systems that can be adjusted or controlled through gestures or movements, without the need for physical switches or remote controls. This technology offers an intuitive way to interact with lighting, enhancing convenience and accessibility.

Ghosting: A faint or secondary image caused by reflections or refracted light in lighting fixtures, often seen as an unwanted effect in architectural and display lighting.

Gimbal Ring: A type of adjustable mounting for recessed lighting fixtures that allows the direction of the light beam to be changed. Gimbal rings are useful for accent lighting or illuminating specific areas or objects.

Glare: The discomfort or impairment of vision experienced when parts of the visual field are excessively bright in comparison to the background. It can be categorized as direct glare (from visible light sources) or reflected glare (from light reflected off surfaces).

Glare Control: Strategies and devices implemented in lighting design to minimize glare, such as shielding, diffusing, or correctly positioning light sources.

Glare Reduction Rating (GRR): A metric used to evaluate the effectiveness of a lighting fixture’s ability to minimize glare. A higher GRR indicates better performance in reducing visual discomfort from bright light sources.

Glare Shield: An accessory or design feature of a lighting fixture that blocks or redirects light to prevent direct view of the light source, reducing glare and improving visual comfort.

Glass Block Lighting: A design technique where glass blocks or bricks are integrated with internal lighting, creating illuminated architectural features that offer both aesthetic appeal and natural light diffusion.

Global Illumination: A term borrowed from computer graphics and visualization, referring to techniques that simulate both direct and indirect light reflection to achieve realistic lighting effects. In physical spaces, it can refer to the comprehensive planning of both natural and artificial light sources to create a cohesive lighting environment.

Glow Effect: A soft, diffused light that appears to emanate from around or behind objects or architectural features, creating a subtle halo or glow. This effect is often used for mood lighting or to highlight architectural details.

Glow Wire Test: A safety test for lighting products that simulates the effects of heat on a luminaire to check for fire hazards. It ensures that materials used in lighting fixtures do not ignite under high temperatures.

Gobo: A physical template placed in front of a light source to control the shape of the emitted light. Used in theatrical lighting and architectural lighting design to create patterns or textured lighting effects.

Goniometric Diagram: A graphical representation of a light source’s distribution pattern, showing how light intensity varies with angle. It’s a crucial tool for understanding and predicting how a fixture will illuminate a space.

Goniophotometer: A device used to measure the light emitted by a source in various directions. It helps in determining the light distribution characteristics of luminaires for accurate lighting design and analysis.

Grazing Light: A lighting technique where light is positioned close to a surface and aimed at a shallow angle to accentuate textures, such as brick or stone walls, by casting shadows that highlight the surface’s features.

Green Lighting: Refers to environmentally friendly lighting solutions that minimize energy consumption and reduce environmental impact. This includes the use of LED lighting, energy-efficient designs, and lighting controls.

Greenwashing: The practice of misleading consumers about the environmental benefits of a lighting product or technology. It’s important for consumers to verify claims and look for independent certifications, such as Energy Star.

Grid Ceiling: A ceiling type consisting of a grid of metal bars that support lightweight ceiling tiles or panels. Lighting fixtures can be mounted within this grid, allowing for flexible and easily adjustable lighting layouts.

Grille: A protective or decorative grid or screen placed over a light fixture. Besides adding an aesthetic element, grilles can help diffuse light and protect the fixture from debris or impact.

Ground Fault Circuit Interrupter (GFCI) for Outdoor Lighting: A device that quickly shuts off an electrical circuit when it detects that current is flowing along an unintended path, such as through water or a person. GFCIs are essential for outdoor and bathroom lighting fixtures to prevent electrical shock.

Ground Lighting: Lighting that is installed at or near ground level to illuminate paths, landscaping, or architectural features from below, enhancing safety and aesthetics.

Group Relamping: The practice of replacing all the light bulbs in a given area or system at the same time, rather than replacing bulbs individually as they fail. This approach can be more efficient and ensure consistent lighting quality.

Guide Light: A small, often low-intensity light used to mark pathways, steps, or edges for safety and navigation, especially in low-light conditions.

Guided Light Technology: Refers to the use of optical fibers or specially designed waveguides to direct light from a source to a specific location. This technology enables innovative lighting applications and designs, including illuminated signage and accent lighting.

Halo Effect: A lighting phenomenon where bright light surrounds a subject or object, creating a “halo.” This effect can be intentional for aesthetic or emphasis purposes or unintentional, sometimes resulting in glare or reduced visibility.

Halogen Lamp: A type of incandescent lamp that uses a halogen gas in order to increase both light output and rated life. Halogen lamps are known for their ability to maintain luminous flux over time, compared to traditional incandescent lamps that may darken.

Handheld Light Meter: A device used to measure the intensity of illumination in a space, typically in lux or foot-candles. Light meters help designers and photographers ensure adequate lighting for various tasks or settings.

Hard Light: A type of lighting that creates sharp, distinct shadows with high contrast between light and dark areas. It’s often achieved with a direct, undiffused light source and can be used to create dramatic effects or emphasize texture.

Hardscape Integrated Lighting: Lighting seamlessly integrated into outdoor hardscape elements like paving, walls, or steps to enhance aesthetics, safety, and usability of outdoor spaces without the fixtures being prominently visible.

Harmonic Distortion: Unwanted frequencies added to the original signal by an electronic device, including lighting equipment. In lighting, excessive harmonic distortion can lead to inefficiencies and interference with other electronic devices.

Haze: A lighting effect that involves a slight diffusion or softening of the light, often used in photography, film, and theatrical lighting to create a sense of depth or ambiance without significantly reducing visibility.

Headlamp: A light source attached to the head, used in situations where hands-free operation is needed, such as in mining, surgery, or outdoor activities. Headlamps provide focused illumination in the direction the user is looking.

Heat Sink: A component of a lighting fixture, especially LED luminaires, designed to dissipate heat away from the light source. Effective heat sinks help to maintain the efficiency and lifespan of LEDs.

Heliostat: A mirror or set of mirrors used to reflect sunlight into a predetermined location, typically used in solar power applications but also for natural lighting purposes to direct sunlight into deep interiors of buildings.

Hemispherical Illuminance: A measure of the illuminance on a surface from light arriving from all directions above the horizontal. This measurement considers both direct sunlight and diffuse sky radiation, important in daylighting analysis.

Hexagonal Beam Spread: A pattern of light distribution that takes on a hexagonal shape, often used in landscape lighting to cover ground areas efficiently while minimizing overlap and waste.

High Bay: Referencing “Highbay Lighting,” this term specifically denotes the fixtures used in these applications, designed to distribute light effectively over a wide area from a high mounting point.

High CRI Lighting: Lighting that features a Color Rendering Index (CRI) value close to 100, indicating that it renders colors accurately in comparison to natural daylight. High CRI lighting is essential in applications where color fidelity is critical, such as art galleries and retail environments.

High Dynamic Range Lighting (HDRL): In architectural and display lighting, HDRL refers to systems designed to cover a wide range of illuminance, allowing for dramatic contrasts and visual experiences similar to high dynamic range imaging in photography.

High-Intensity Discharge (HID) Lamp: A type of electrical gas-discharge lamp that produces light by means of an electric arc between tungsten electrodes housed inside a translucent or transparent fused quartz or fused alumina arc tube. This tube is filled with gas and metal salts, facilitating the arc’s initial strike. Once the arc is started, it heats and evaporates the metal salts, forming a plasma that increases the intensity of light produced by the arc and reduces its power consumption.

High-Speed Sync (HSS) Lighting: In photography and film, a technique that allows flash lighting to synchronize with camera shutters at high speeds, enabling better exposure control in brightly lit or outdoor conditions.

Highbay Lighting: Lighting designed for use in high-ceiling environments (typically above 20 feet), such as warehouses, manufacturing facilities, and large retail spaces. Highbay fixtures are designed to provide adequate illumination at ground level from a high mounting height.

Highlighting: A lighting technique used to draw attention to specific features or objects, such as artwork, architectural details, or landscape elements, by illuminating them more brightly than their surroundings.

Holiday Lighting: Temporary decorative lighting used to celebrate holidays and festive occasions. It includes string lights, illuminated figures, and other decorative elements that add to the festive atmosphere.

Horizontal Illuminance: The amount of light falling on a horizontal surface, typically measured in lux or foot-candles. This measurement is critical for tasks that require good visibility and is a key factor in lighting design.

Hospitality Lighting: Specialized lighting designed to create welcoming, comfortable environments in hotels, restaurants, and other hospitality venues. It includes ambient, task, and accent lighting tailored to enhance the guest experience.

Hot Restart Time: The time required for certain types of lamps, especially HID lamps, to reach full brightness after being turned off and then on again. This characteristic is important in applications where lights are frequently switched.

Housing: The part of a light fixture that encloses the lamp or light source, providing mechanical support and protection. Housing can also help manage heat and direct light output.

Hue: A dimension of color that is determined by the wavelength of light; the attribute of a visual sensation according to which an area appears to be similar to one of the perceived colors:red, yellow, green, and blue, or to a combination of two of them.

Hue Saturation Intensity (HSI): A color model used in lighting and color science that describes colors by their hue (color), saturation (colorfulness), and intensity (brightness), useful in the design of dynamic and colored lighting systems.

Human-Centric Lighting (HCL): Lighting that is designed to improve health, well-being, and performance by aligning artificial light with the human circadian rhythm. HCL systems often adjust color temperature and intensity throughout the day.

Hybrid Lighting Fixture: A lighting fixture that combines multiple types of light sources, such as LED with traditional incandescent or fluorescent, to leverage the benefits of each type, such as energy efficiency with warm light quality.

Hybrid Solar Lighting: A system that captures sunlight and directs it indoors using optical fibers, supplementing with artificial light as necessary. The system dynamically adjusts, providing energy-efficient lighting that mimics natural daylight.

IESNA (Illuminating Engineering Society of North America): A recognized technical authority on illumination, setting standards and publishing guidelines for the lighting industry to ensure the quality and consistency of lighting design.

IP Rating: Expanding on the Ingress Protection Rating, it’s crucial for outdoor and bathroom lighting fixtures to ensure durability against environmental elements like dust and water.

Illuminance: The total luminous flux incident on a surface per unit area. It is measured in lux (lx) or foot-candles (fc), indicating how much light is falling on a surface and is critical for determining adequate lighting levels for various tasks and environments.

Illuminance Gradient: The rate at which illuminance changes across a surface. A smooth gradient provides a gradual transition between light and dark areas, enhancing visual comfort.

Illuminance Hierarchy: The strategic use of varying light levels to emphasize certain areas or elements within a space, guiding attention and creating visual interest.

Illuminance Meter: A device used to measure the amount of light falling on a surface, typically used by lighting professionals to ensure that lighting designs meet required standards for visibility and comfort.

Illuminance Uniformity: The measure of how evenly light is distributed across a given area. High uniformity means the light levels are consistent throughout the space, which is important for task performance and visual comfort.

Illuminated Egress Pathways: Lighting specifically designed to guide occupants safely out of a building during an emergency. It includes exit signs and path lighting that remains operational in power outages.

Illuminated Signage: LighSigns that are backlit or contain internal lighting to make them visible in low-light conditions. Illuminated signage is widely used for business identification, wayfinding, and advertising.t that falls on a surface or object. Measuring incident light helps in understanding how well a space is illuminated or how a particular object will appear under certain lighting conditions.

Illumination Engineering: The branch of engineering focused on the application of lighting design principles and technologies to optimize visual performance, energy efficiency, and aesthetic appeal in various environments.

Illumination Levels: The specified amount of light required for different environments, tasks, or activities, usually determined by standards or guidelines to ensure adequate visibility and comfort.

Impact Resistance: The ability of a lighting fixture to withstand physical forces or impacts without being damaged. This is particularly important for outdoor, industrial, or sports lighting applications where fixtures may be exposed to balls, tools, or other objects.

In-Situ Measurement: The practice of measuring the lighting conditions of an installation at its actual location, as opposed to laboratory measurements. This approach ensures lighting designs meet practical requirements and user needs.

Incandescent Dimming: The process of reducing the light output of incandescent lamps by lowering the voltage supplied to the filament. This not only dims the light but also changes the color temperature to a warmer hue, similar to sunset or candlelight.

Incandescent Equivalent: A term used to compare the light output of energy-efficient lamps, such as LEDs and CFLs, to that of traditional incandescent lamps. It helps consumers understand the brightness of different lamps in familiar terms.

Incandescent Lamp: A light source that produces light by heating a filament wire to a high temperature until it glows. The filament is enclosed in a glass bulb to protect it from oxidation. Incandescent lamps are known for their warm light but are less energy-efficient compared to modern lighting technologies.

Incident Lighting: Similar to “Incident Light,” this term focuses more broadly on how directed light impacts an object or surface, influencing the design decisions for achieving desired visual effects or tasks.

Indirect Glare: Glare resulting from light reflecting off surfaces into the eyes, which can be just as uncomfortable as direct glare from a light source itself. Managing indirect glare is essential in workspace lighting design.

Indirect Lighting: A lighting technique where light is directed towards the ceiling or walls and reflected back into the room, creating a diffused and uniform light that minimizes shadows and glare.

Infrared Radiation (IR): Electromagnetic radiation with longer wavelengths than visible light, not visible to the human eye but perceived as heat. Some lighting sources, like incandescent lamps, emit a significant amount of IR, affecting heat management in lighting design.

Ingress Protection (IP) Rating: A two-digit code that indicates the degree of protection an electrical enclosure offers against solids (like dust) and liquids. It’s crucial for lighting fixtures used in outdoor or industrial environments where water, dust, and foreign objects are a concern.

Innovative Lighting Design: Approaches or concepts in lighting design that push the boundaries of traditional practices, incorporating new technologies, materials, or methodologies to create unique and effective lighting solutions.

Installation Art Lighting: Lighting designed specifically for art installations, where lighting plays a critical role in experiencing the artwork. It involves carefully planned illumination that enhances the artistic expression without overshadowing the artwork itself.

Integrated Lighting: Lighting that is built into architectural elements or furniture, such as shelves, cabinets, or mirrors. It is designed to blend seamlessly with the environment, providing functional or decorative illumination without visible fixtures.

Integrating Sphere: A device used to measure the total light output of lamps and other light sources. It is a hollow spherical cavity with its inner surface coated with a diffuse white reflective coating, allowing for the measurement of light from all directions.

Interactive Lighting: Lighting systems that respond to user input or environmental changes, allowing for dynamic adjustments in light settings. This can include color, intensity, and pattern changes based on motion, sound, or other triggers.

Inverse Square Law: A principle stating that the intensity of light is inversely proportional to the square of the distance from the source. This law is fundamental in calculating the expected illuminance at different distances from a light source.

Isolines: Lines on a diagram or map connecting points of equal value. In lighting, isolines on an illuminance map show areas of equal light intensity, helping designers assess the effectiveness of a lighting plan.

J-Box: Short for junction box, a J-Box is an enclosure within a building that contains electrical connections. In lighting, fixtures may be designed for direct mounting to a J-Box, which safely houses all wiring connections.

Jalousie Lighting: A concept inspired by jalousie windows, where slats of light are directed or diffused to create a louvered lighting effect. This can be used for both aesthetic and functional purposes, controlling light direction and intensity.

Japanese Lantern: A type of lantern made of paper or silk, with a frame of bamboo, wood, or metal. These lanterns, often used in festivals or as decorative elements, can inspire modern lighting designs that mimic their soft, diffused light and aesthetic form.

Java Programming for Smart Lighting: Referring to the use of the Java programming language in developing software for smart lighting systems. Java can be used to create applications that control lighting based on user input, sensor data, or other criteria.

Jazz Lighting: An informal term that might describe dynamic, vibrant lighting setups used in live music venues, particularly jazz clubs. Such lighting often involves a mix of spotlighting, ambient, and mood lighting, designed to complement the energy and improvisation of jazz performances.

Jewel Light: Decorative lighting fixtures that incorporate glass, crystals, or other reflective materials to create sparkling, jewel-like effects. These lights are often used as accent lighting in retail, hospitality, or residential settings.

Jewelry Display Lighting: Specialized lighting designed to highlight the brilliance and craftsmanship of jewelry in display cases. Proper lighting is crucial for showcasing the sparkle and detail of precious metals and stones.

Jitter: In lighting, particularly dynamic or programmable lighting systems, jitter refers to small, rapid variations in light output or color that can occur due to control signal inconsistencies. Minimizing jitter is important for smooth transitions and stable lighting effects.

Job Site Lighting: Portable lighting used on construction sites, workshops, and areas where temporary illumination is needed. Job site lighting needs to be durable, bright, and adaptable to various environments.

Joule: A unit of energy in the International System of Units (SI). In lighting, it can be used to quantify the energy consumption of light sources. One joule per second equals one watt, linking the concepts of energy and power in lighting applications.

Joule Efficiency: While not a standard term, it could relate to the efficiency with which a lighting system converts electrical energy (joules) into light. Higher joule efficiency means more light output for less energy consumption, a key goal in sustainable lighting design.

Joule’s Law: Fundamental in electrical engineering and lighting, Joule’s Law relates to the power dissipation in an electrical circuit. It states that the power of heat generated in a conductor is directly proportional to the product of its resistance and the square of the current. This principle is key in designing electrical systems for lighting to ensure safety and efficiency.

Junction Box Adaptability: The capacity of lighting fixtures to be compatible with various types of junction boxes, a critical consideration in retrofitting and renovation projects where existing electrical installations must be accommodated.

Junction Box Mounting: The method of installing lighting fixtures by attaching them directly to an electrical junction box, ensuring a secure and safe electrical connection. It’s a common installation technique for ceiling and wall lights.

Junction Temperature: The highest operating temperature of the actual semiconductor in an LED device. The junction temperature is a critical factor in the performance and longevity of LEDs, affecting their light output, color stability, and lifespan.

Junction Temperature: The temperature at the semiconductor in an LED device. It’s a critical factor affecting the performance, light output, color stability, and lifespan of LED lights. Managing junction temperature through proper heat sinking is essential for maintaining LED efficiency and reliability.

Just Noticeable Difference (JND) in Lighting: Borrowed from psychophysics, JND refers to the minimum change in stimulus intensity required to produce a detectable variation in sensory experience. In lighting, it can relate to the smallest change in illuminance or color temperature that a human observer can detect, which is crucial in dimming technology and creating seamless transitions in adaptive lighting systems.

Juxtaposed Lighting Scenes: The use of contrasting lighting scenes within a single space to create a dramatic or visually engaging environment. This technique can emphasize architectural features, art, or create varied ambiance within an area.

K-Rating: In the context of electrical transformers, including those used in lighting systems, the K-rating indicates the transformer’s ability to handle non-linear loads that produce harmonics. A higher K-rating suggests better performance and longevity under such conditions.

Kaleidoscopic Effects: Lighting effects that replicate the multi-colored, symmetrical patterns seen in a kaleidoscope. These effects can be achieved through specialized lenses, reflective materials, or digital lighting technologies, adding visual interest and ambiance.

Kelvin (K): A unit of measure for the color temperature of light sources, representing the hue of the light emitted. The Kelvin scale ranges from warm (lower values, such as 2700K, which produces a yellowish light) to cool (higher values, such as 6500K, which produces a bluish light), simulating the light from the morning to midday.

Kelvin Scale (K): While technically starting with a “K,” the Kelvin scale is essential in describing the color temperature of light sources, from warm (lower Kelvin numbers) to cool (higher Kelvin numbers). It helps in selecting lighting that creates the desired atmosphere or functional outcome in a space.

Kelvin Shift: The change in color temperature of a light source over time or due to dimming. As some light sources, especially LEDs, are dimmed, they can shift to a warmer color temperature, mimicking the behavior of incandescent bulbs.

Kerb Lighting: Lighting installed along curbs or kerbs in streetscapes, pathways, or parking areas. It enhances safety for pedestrians and drivers by delineating edges and obstacles.

Key Light: In photography, film, and stage lighting, the key light is the primary source of light for a scene or subject. It determines the overall look, direction, and shadows in the lighting setup, often complemented by fill and backlights for depth and dimension.

Key Lighting Ratio: In photography and cinematography, this refers to the contrast ratio between the key light (the main source of light) and the fill light (used to reduce shadows). The ratio affects the mood and three-dimensionality of the scene.

Key Switch Control: A lighting control mechanism that requires a key to operate, offering an added level of security and preventing unauthorized adjustments to lighting settings. This is especially useful in public or commercial spaces.

Keystone Correction: In architectural lighting, this refers to adjusting the beam of light to compensate for angular distortion, particularly when projecting light or images onto surfaces at an angle. It ensures the light or projected image retains its intended shape and size.

Kicker Light: In photography and cinematography, a kicker light is placed behind or to the side of the subject to create a rim of light on the edge, enhancing separation from the background and adding depth to the image.

Kilolumen: A unit of luminous flux equal to 1,000 lumens. Used in lighting to quantify the total visible light output of a source, providing a scale for comparing the brightness of different lighting products.

Kilolux (klx): A unit of illuminance equal to 1,000 lux. Used in professional lighting design and studies where high levels of light are required, such as in sports stadiums or industrial inspection areas.

Kilowatt Hour (kWh): A unit of energy measurement that represents the amount of energy used by a 1,000-watt device running for one hour. In lighting, kWh is used to calculate the energy consumption and cost-effectiveness of lighting systems over time.

Kinesthetic Lighting Environment: A lighting design concept that considers the movement of people within a space, creating a dynamic lighting environment that responds to or complements human activity, potentially through motion sensors or programmable lighting scenes.

Kinetic Lighting: Lighting systems that include moving elements, either through physical movement of the fixtures or dynamic changes in light color and intensity. Kinetic lighting adds a lively and interactive aspect to lighting design, often used in entertainment and public spaces.

Kinetic Shadow Play: The creation of dynamic shadows through the movement of light sources or objects between the light and a surface. This technique can be used for artistic installations, theatrical performances, or to add a lively ambiance to a space.

Kiosk Lighting: Lighting designed for kiosks and display units in malls, exhibitions, and outdoor settings. Kiosk lighting enhances visibility, attracts attention, and improves the display of information or products.

Kneeling Light: A term that could describe low-level lighting designed to illuminate the floor or ground, enhancing visibility and safety, especially in stairwells, pathways, and outdoor landscapes.

Knockout: A pre-cut, removable section in an electrical box or lighting fixture that allows for the passage of wires. Knockouts make it easier to route wiring during installation or accommodate additional fixtures.

Knuckle Joint: A flexible joint in a light fixture that allows it to be angled or positioned as needed, similar to a knuckle mount. It’s particularly useful in landscape and spotlighting applications for precise aiming.

Knuckle Mount: A type of mounting mechanism for outdoor and landscape lighting fixtures that allows for adjustable aiming. The knuckle mount lets users tilt and rotate the fixture to direct light precisely where it’s needed.

Knurling Detail on Fixtures: A decorative feature on some lighting fixtures that includes a pattern of small, precise ridges. Knurling can enhance grip for adjustable fixtures and add a tactile and visual element to the design.

Krypton Bulbs: Light bulbs filled with krypton gas, which increases efficiency and light output compared to standard incandescent bulbs. Krypton bulbs offer a brighter light with a longer lifespan, making them suitable for various applications.

LED (Light Emitting Diode): A semiconductor device that emits light when an electric current passes through it. LEDs are highly efficient and have a long life span, making them a popular choice for sustainable lighting solutions across all sectors.

LED Array: A configuration of multiple LED chips mounted on a single surface or substrate to create a powerful and uniform light source. LED arrays are used in a variety of lighting applications where high brightness and efficiency are required.

Lamp: In the context of lighting, a lamp is a source of light, traditionally referred to as a bulb. Lamps can vary in technology, including incandescent, fluorescent, LED, and others, each with specific characteristics and applications.

Lamp Holder: The part of a light fixture that provides mechanical support and electrical connections for a lamp. Lamp holders vary in design and size to accommodate different types of lamps and mounting requirements.

Lamp Life: The expected operational lifespan of a lamp, usually given in hours. It represents the time period after which a significant portion of lamps will still function but may produce less light than when they were new.

Landscape Accent Lighting: Lighting that focuses on highlighting landscape features such as trees, plants, sculptures, or architectural elements. Accent lighting enhances the aesthetic appeal of outdoor spaces and draws attention to specific details.

Landscape Lighting: Outdoor lighting that enhances and illuminates gardens, paths, and architectural features. It improves safety, security, and aesthetics, extending the usability of outdoor spaces after dark.

Laser Lighting: Lighting technology that uses lasers as a light source, known for producing highly intense and focused beams of light. Laser lighting is used in entertainment, architectural lighting, and specialty applications requiring precise illumination.

Light Guide: A physical device that directs the transmission of light from a light source to a specific location, often used in optical fibers and edge-lit LED panels. Light guides are designed to optimize light distribution and minimize loss.

Light Layering: A design strategy that involves using multiple types of lighting (ambient, task, and accent) in layers to create depth, interest, and functionality in a space. Light layering helps to balance illumination, reduce glare, and enhance the overall atmosphere.

Light Pollution: Unwanted or excessive artificial light that can have adverse effects on wildlife, obscure the night sky, disrupt ecosystems, and negatively impact human health. Strategies to reduce light pollution include using full cutoff fixtures, proper shielding, and minimizing unnecessary outdoor lighting.

Light Well: An architectural feature designed to allow natural light to penetrate deep into a building, typically a vertical shaft that channels daylight from the roof or upper levels down to lower or underground floors.

Lighting Audit: An examination of existing lighting conditions in a space or facility, typically conducted to identify opportunities for improvement, energy savings, and upgrades to more efficient lighting solutions.

Lighting Contrast: The difference in brightness between two areas or objects, which can affect visibility and perception. Proper management of lighting contrast is important in design to ensure comfort and functionality, avoiding harsh transitions or shadows.

Lighting Control System: An intelligent network-based solution that allows for the remote operation and management of lighting within a building or outdoor space. It can include dimmers, timers, sensors, and programmable switches to enhance energy efficiency and user comfort.

Lighting Fixture: The complete assembly that houses a lamp or lamps and may include elements for directing the light, protecting the bulbs, and connecting to the electrical power source. Lighting fixtures come in various styles and configurations for different applications.

Lighting Retrofit: The process of replacing outdated or inefficient lighting fixtures, lamps, and control systems with newer, energy-efficient technologies to reduce energy consumption and improve lighting quality.

Lighting Scheme: A planned combination of lights and fixtures designed to achieve a specific effect or fulfill a particular function within a space. Lighting schemes consider the placement, type, intensity, and color of light to create the desired ambiance or functionality.

Linear Fluorescent Lamp: A type of fluorescent lamp designed as a long, cylindrical tube. Linear fluorescent lamps are commonly used in commercial and institutional settings for general illumination, offering energy efficiency and long life.

Linear Lighting: A style of lighting fixture that produces light along a linear path, commonly used in architectural lighting to highlight straight lines, create boundaries, or provide uniform illumination across long surfaces.

Louver: A device consisting of multiple slats or vanes designed to control the direction and amount of light entering a space, or to prevent glare by shielding the light source. Louvers can be adjustable or fixed and are used in both natural and artificial lighting applications.

Lumen (lm): A unit of luminous flux in the International System of Units (SI), representing the quantity of visible light emitted by a source. The lumen measures the total amount of visible light from a lamp or light source, indicating its brightness.

Lumen Maintenance: A measure of how well a light source maintains its output over time. It is often expressed as a percentage of initial lumens that remain after a certain number of operating hours, indicating the long-term performance and reliability of the light source.

Luminaire: A complete lighting unit consisting of a lamp or lamps along with the parts designed to distribute the light, position and protect the lamps, and connect the lamps to the power supply. Luminaires are what most people refer to as light fixtures.

Luminaire Canopy: A component of some pendant and ceiling-mounted luminaires that covers the electrical box and connection points, providing a finished look and supporting the weight of the fixture.

Luminaire Distribution: The pattern of light emitted by a luminaire, classified into types such as direct, indirect, or diffused. The distribution affects how light is spread across a room or area, influencing visibility, shadows, and the perception of space.

Luminaire Efficiency: The ratio of total lumens emitted by a luminaire to the lumens produced by the light source(s) alone. It measures how effectively a luminaire distributes the light from the source, accounting for losses due to reflection, absorption, or diffraction within the fixture.

Luminance (L): A measure of the brightness of a surface as perceived by the human eye, taking into account the surface’s illuminance and reflectance. It is measured in candela per square meter (cd/m²).

Luminous Efficacy: The ratio of luminous flux (in lumens, lm) to power (in watts, W). It measures the efficiency of a light source in converting electrical energy to visible light.

Luminous Flux (Φ): The total amount of visible light emitted by a source, measured in lumens (lm). Luminous flux is a measure of the perceived power of light as adjusted by the human eye’s sensitivity to various wavelengths.

Luminous Intensity: The amount of luminous flux in a specific direction, measured in candela (cd). It is a measure of how bright the light appears when looking directly at the light source.

Lux (lx): The unit of illuminance, measuring the amount of luminous flux per unit area. One lux is equal to one lumen per square meter. It is used to gauge how much light is received on a surface.

Lux Meter: A device used to measure illuminance, providing readings in lux. Lux meters are essential tools for lighting professionals to ensure that spaces are adequately lit according to design specifications and standards.

Mains Frequency: The oscillation rate of the alternating current (AC) supplied from the power grid, typically 50 Hz or 60 Hz depending on the region. Lighting systems, especially those with electronic components, must be compatible with the mains frequency to function properly.

Mains Voltage: The standard electrical voltage supplied to buildings (typically 120V or 230V, depending on the country). Lighting fixtures and systems must be compatible with the mains voltage to operate safely and effectively.

Maintenance Factor: A factor used in lighting design to account for the reduction in light output of a lighting system over time due to lamp lumen depreciation, dirt accumulation on fixtures, and other factors affecting performance.

Manual Dimming: The adjustment of light intensity through manual controls, such as dimmer switches. Manual dimming allows users to customize lighting levels based on preference or activity, enhancing comfort and saving energy.

Manual Override: A feature in automated lighting systems that allows users to manually control the lighting, bypassing automatic settings or schedules. This flexibility is essential for accommodating special events or specific user needs.

Maxwellian View: A concept related to the focus and distribution of light, particularly in optical and lighting studies, named after the physicist James Clerk Maxwell. It involves viewing an illuminated field through a small aperture to analyze the light’s properties, such as coherence or collimation.

Mercury Vapor Lamp: A type of high-intensity discharge (HID) lamp that produces light by an electric arc through vaporized mercury. These lamps are known for their high efficiency and intense light output but have fallen out of favor due to their poor color rendering properties and the development of more efficient and environmentally friendly lighting technologies.

Mesh Network Lighting: A network topology used in smart lighting systems where each light fixture can communicate with adjacent fixtures, creating a mesh of interconnected devices. This allows for more reliable control and scalability of lighting systems.

Metal Halide Lamp: A type of HID lamp that produces light by passing an electric arc through a mixture of vaporized mercury and metal halides. Metal halide lamps offer high luminous efficacy and good color rendering, suitable for outdoor, industrial, and retail lighting.

Metallic Reflector: A reflector made from polished metal surfaces used in lighting fixtures to direct and enhance light output. Metallic reflectors are effective in creating focused beams of light and in applications requiring high reflectivity.

Microlens Array: A component used in some LED lighting fixtures to distribute light more evenly or to create specific lighting effects. Microlens arrays consist of numerous small lenses that can precisely control the direction and spread of light.

Microprismatic Diffuser: A type of light diffuser that uses tiny prisms to distribute light evenly and reduce glare. These diffusers are effective in office and commercial lighting fixtures, where visual comfort is a priority.

Minimalist Lighting: A design approach that focuses on simplicity and functionality, using the fewest and simplest fixtures possible to achieve the desired lighting effect. Minimalist lighting emphasizes clean lines and unobtrusive designs.

Mirror Lighting: Lighting fixtures or techniques specifically designed to illuminate mirrors, typically used in bathrooms, dressing rooms, or makeup areas. Proper mirror lighting ensures even, shadow-free illumination for grooming and personal care tasks.

Modulation: In lighting, modulation can refer to the variation in light output or color over time. Dynamic lighting systems might modulate lighting to mimic natural daylight cycles or to create engaging visual environments.

Monochromatic Light: Light that has a single wavelength or color. In lighting design, monochromatic light sources are used in applications that require a specific color of light, such as in certain types of accent lighting or for creating special atmospheric effects.

Mood Board for Lighting: A visual tool used by designers to conceptualize and communicate the mood, style, and emotional feel of a lighting scheme. Mood boards may include images, materials, color palettes, and lighting fixture samples.

Mood Lighting: Lighting designed to create a specific atmosphere or mood within a space. It often involves adjustable intensities and color temperatures to evoke different feelings or accommodate various activities.

Moonlighting: A landscape lighting technique that simulates natural moonlight by placing fixtures high in trees or structures, casting soft, dappled light downward. This creates a serene, natural nighttime environment.

Motion Sensor: A device that detects physical movement in a designated area and automatically activates the lighting system. Motion sensors are used for security purposes and to save energy by turning lights on and off as needed.

Motion Tracking Lighting: Advanced lighting systems that adjust the direction and intensity of light based on the movement of people within a space. This technology enhances energy efficiency and provides dynamic illumination that responds to occupancy patterns.

Mounting Bracket: A hardware component used to secure a lighting fixture to a surface, structure, or pole. Mounting brackets must be sturdy and properly designed to support the weight and configuration of the fixture.

Mounting Height: The vertical distance from the floor or ground to the light source or luminaire. Mounting height is crucial for calculating illuminance and ensuring proper light distribution in a space.

Mounting Options: The various ways lighting fixtures can be installed or attached, including ceiling mount, wall mount, pendant, recessed, track, and free-standing. Each option offers different aesthetic and functional benefits suited to particular applications.

Multi-Circuit Track Lighting: Track lighting systems that feature multiple electrical circuits within a single track, allowing fixtures on the same track to be controlled independently. This adds versatility to lighting design, enabling varied lighting scenes.

Multi-Level Lighting: A lighting strategy that involves layers or levels of light within a space, including ambient, task, and accent lighting. Multi-level lighting creates visual interest and allows for flexibility in how a space is used and perceived.

Multifaceted Reflector (MR) Lamps: Compact, halogen or LED light bulbs that include a precision-engineered reflector to direct the light. These are commonly used in track lighting, recessed ceiling lights, and spotlighting, offering focused illumination with controlled beam angles.

Multispectral Lighting: Lighting that can produce light across multiple spectra, not just visible light. It has applications in agriculture, medical fields, and art preservation, where different light wavelengths can have specific effects or benefits.

Müller-Lyer Illusion: A visual illusion that is relevant in the context of architectural lighting design. It demonstrates how visual perception can be influenced by the context in which an object is viewed, which can be important for lighting designers to consider when planning lighting schemes that affect the perception of space.

NEMA (National Electrical Manufacturers Association): An organization that develops performance and other standards for electrical products in the U.S., including lighting equipment. NEMA standards help ensure compatibility, safety, and environmental sustainability of electrical products.

NEMA Enclosure Types: Specific classifications provided by the National Electrical Manufacturers Association (NEMA) that describe the types of environments in which an electrical enclosure can be used, including those suitable for various outdoor and industrial lighting applications.

NEMA Rating: Refers to the National Electrical Manufacturers Association ratings for electrical enclosures, including those for lighting fixtures. NEMA ratings indicate the level of protection against environmental elements like dust, water, and impact.

Nadir: The point directly below a particular location or object, often referred to in lighting design when discussing the distribution of light from a fixture towards the ground or floor directly beneath it.

Nano-Optics: The study and application of optical technologies and materials at the nanoscale, including in lighting design. Nano-optics can enhance the efficiency, control, and quality of light emission from sources like LEDs.

Nanometer (nm): A unit of measurement equal to one billionth of a meter, used to specify the wavelength of light, particularly in the context of the color spectrum and LEDs. Different wavelengths correspond to different colors of visible light.

Nanotechnology in Lighting: The application of nanotechnology in the development of lighting products, including LEDs. Nanoscale materials and structures can improve light output, efficiency, and color rendering, leading to innovative lighting solutions.

Narrow Beam Angle: Refers to light sources with a focused beam of light, typically less than 25 degrees. Narrow beam angles are used for spotlighting, accent lighting, and highlighting specific features or objects.

Narrow Spectrum Lighting: Lighting that emits light in a limited range of wavelengths. Narrow spectrum lighting can be used for specific applications, such as growing plants, therapeutic purposes, or creating special atmospheric effects.

Natural Diffusion: A lighting effect achieved by utilizing materials or environmental conditions that naturally scatter light, such as fog, mist, or translucent fabrics, to create a soft, evenly distributed light without harsh shadows.

Natural Light: Light from the sun. In lighting design, maximizing natural light through windows, skylights, and other architectural elements is essential for energy efficiency, occupant comfort, and well-being.

Natural Lighting Design: The process of planning and implementing lighting schemes that primarily utilize daylight, incorporating elements such as window placement, skylights, and reflective surfaces to enhance indoor lighting with natural light.

Naturalistic Lighting: A design approach that aims to mimic the variability and qualities of natural daylight within built environments, enhancing spaces with lighting that changes in color temperature and intensity throughout the day.

Neon Lamp: A low-pressure gas discharge lamp filled with neon gas, which emits light through fluorescence when an electric current is passed through it. Neon lamps are commonly used for signage and decorative lighting due to their vibrant colors and ability to be shaped into various forms.

Neon Lighting: A type of cold cathode gas-discharge light that uses neon or other gases to produce colored light or a luminous glow. Neon lighting is commonly used for signs, art, and architectural highlights.

Networked Lighting Control (NLC): Advanced lighting control systems that connect fixtures and control devices over a network, allowing for centralized management, automation, and integration with other building systems for optimized performance and energy savings.

Neutral Density Filter: A filter that reduces the intensity of all wavelengths or colors of light equally, without changing the light color. In lighting design, it’s used to control the brightness of a scene without affecting the color temperature.

Neutral White: A term describing LED and other artificial light sources that emit light with a color temperature typically between 3500K and 4500K, providing a balance between warm and cool light.

Niche Luminaire: A compact lighting fixture specifically designed to fit into small spaces or recesses, providing focused or accent lighting. These are commonly used to highlight artworks, architectural details, or merchandise in display settings.

Night Vision Preservation: Lighting design that considers the impact of artificial light on human night vision. Using lower intensity lights or specific colors (like red) can help preserve night vision in environments where it’s critical, such as astronomical observatories or wildlife habitats.

Nightlight: A small, low-powered electrical light fixture, often used in bedrooms, bathrooms, and hallways to provide soft illumination during nighttime hours for safety and comfort.

Nightscaping: A design philosophy focused on creating outdoor lighting environments that are both functional and aesthetically pleasing at night. Nightscaping involves careful planning of light sources, intensities, and colors to enhance the nighttime experience of landscapes and architectural features.

Nighttime Aesthetics: The aspect of lighting design focused on creating visually appealing environments during the night. This includes architectural, landscape, and urban lighting schemes that enhance safety, usability, and beauty after dark.

Node-Based Control: In smart lighting systems, a method where individual lights or groups of lights are controlled as nodes in a network, allowing for complex lighting scenes and automation based on various inputs or schedules.

Non-Cutoff Luminaire: A lighting fixture that does not limit the angle of light emission, potentially allowing light to be emitted upward and contributing to light pollution. Contrast with full cutoff luminaires that minimize upward light.

Non-Dimmable LED: An LED light source designed without the capability to adjust its brightness. These LEDs are simpler and often less expensive but lack the versatility of dimmable versions.

Non-Linear Load: Electrical devices that draw a non-sinusoidal current from the power supply, including many modern lighting solutions like LEDs and compact fluorescents. Non-linear loads can cause harmonic distortion in the electrical system.

Non-Photopic Vision: Vision under low light levels where the rods in the human eye are primarily responsible for visual perception, as opposed to cones during daylight (photopic vision). Lighting design for nighttime environments considers non-photopic vision to ensure visibility and comfort.

Non-Visual Lighting: Aspects of lighting that affect physiological and psychological responses in humans, beyond visual perception. This includes effects on circadian rhythms, mood, and alertness, which are influenced by the intensity, timing, and spectral composition of light.

Non-invasive Lighting: Lighting solutions designed to minimally impact the surrounding architecture or environment. This approach is often used in historic preservation, where it’s crucial to illuminate spaces without damaging or permanently altering the original structures.

Notch Filter: In lighting and optical systems, a filter designed to selectively block a specific range of wavelengths or colors. Notch filters can improve the color quality of light sources or protect sensitive materials from specific light frequencies.

Novelty Lighting: Unique and often whimsical lighting fixtures designed more for decorative purposes than for illumination. Novelty lighting can add character and personalization to a space, reflecting individual tastes or themes.

OLED Panels: Thin, flat lighting panels made from organic light-emitting diodes (OLEDs). Unlike point light sources like LEDs, OLED panels produce a uniform, soft light over their entire surface, making them ideal for creating ambient lighting with minimal shadows and glare.

Obstruction Lighting: Lighting used to mark obstructions such as buildings, towers, and other structures to ensure they are visible at night or in poor visibility conditions, primarily for aviation safety.

Obtrusive Light: Light that causes discomfort, distraction, or nuisance, often resulting from poor lighting design or misaligned fixtures. This can include light spill into areas where it’s not wanted or needed, such as into neighboring properties or the night sky, contributing to light pollution.

Occupancy Sensor: A device that detects the presence of people in a space and automatically turns the lights on or off accordingly. This is an effective energy-saving solution that ensures lights are not left on in unoccupied rooms.

Occupancy-based Lighting Control: A system that adjusts lighting levels based on the detected presence or absence of people, using sensors to turn lights on when a space is occupied and off when it is empty. This approach maximizes energy savings and extends the life of lighting fixtures.

Off-Grid Lighting: Lighting systems that operate independently of the main electrical grid, often powered by renewable energy sources such as solar panels. Off-grid lighting is essential in remote areas and for reducing environmental impact.

Off-axis Illumination: Lighting that is directed towards a surface or object from an angle, rather than straight on. This technique can enhance texture, depth, and dimensionality, and is often used in accent lighting to highlight architectural features or artwork.

Omni-Directional Light: Light that is distributed uniformly in all directions. Omni-directional lamps are typically used where a broad, even light distribution is needed, such as in general ambient lighting.

On-board Dimming: Refers to dimming capabilities that are built directly into a lighting fixture or lamp, allowing for brightness adjustment without the need for external controls or dimmers. This feature provides flexibility in adjusting lighting conditions to suit preferences or activities.

Opalescent Glass: Glass with a milky, translucent quality that diffuses light gently, reducing glare. Used in lighting fixtures, opalescent glass creates a soft, even light ideal for creating a warm and inviting atmosphere.

Opaque: A material or surface that does not allow light to pass through. In lighting design, opaque elements may be used to block or control the direction of light, preventing glare and shaping the light distribution in a space.

Open Circuit Voltage: In the context of lighting, particularly LED and solar-powered systems, this term refers to the voltage measured across the terminals of a device when no current is flowing. Understanding open circuit voltage is important for properly matching components in a lighting system to ensure efficient operation.

Optic: The part of a lighting fixture that controls light distribution, including lenses and reflectors designed to direct light output for specific applications, improving efficiency and visual comfort.

Optical Brightening: The use of materials or coatings within a luminaire that enhance the perceived brightness of the light output without increasing energy consumption. This can involve reflective surfaces or phosphorescent materials that improve the efficiency of light distribution.

Optical Control: Components of a lighting fixture designed to shape and direct the light emitted from the lamp. This includes reflectors, lenses, diffusers, and louvers that can influence the intensity, distribution, and quality of the light.

Optical Efficiency: The ratio of the luminous flux (light output) emitted by a luminaire to the luminous flux produced by the light source(s) within it. This measure indicates how effectively a lighting fixture delivers light from the source to the intended area or task, taking into account losses due to reflection, absorption, and diffusion by the fixture’s optical components.

Optical Isolation: In lighting systems, especially those that are digitally controlled, optical isolation refers to a method of preventing high voltages or fluctuations from affecting sensitive control electronics, ensuring stable operation.

Optimum Light Level: The ideal amount of light for performing specific tasks comfortably and efficiently, without causing eye strain or wasting energy. Determining the optimum light level involves considering factors like the nature of the task, the age of the occupants, and the reflective qualities of surfaces in the space.

Organic Light Emitting Diodes (OLEDs): A type of lighting technology that consists of thin, flexible sheets of organic electroluminescent material that emit light when an electric current is applied. OLEDs are used for their potential to create efficient, thin, and flexible lighting panels with a soft, diffused light quality.

Organic Photovoltaics (OPV): A type of solar cell technology that converts light into electricity using organic materials. While not a direct component of lighting design, OPVs can be integrated into building materials, such as window shades or glass, to power LED lighting systems, contributing to sustainable building practices.

Orientable Fixtures: Lighting fixtures designed to be adjusted or moved to direct light precisely where it is needed. These fixtures are particularly useful in task lighting, accent lighting, and adaptive architectural lighting designs.

Orientation Lighting: Lighting designed to aid in navigation through a space or environment, providing cues for direction and highlighting paths, entrances, exits, and key landmarks.

Ornamental Lighting: Decorative lighting that adds aesthetic value to a space, object, or building. It includes fixtures with artistic designs, as well as the strategic use of light to beautify or enhance visual appeal.

Outdoor Lighting: The application of light to outdoor spaces for aesthetics, security, and functionality. This includes street lighting, landscape lighting, architectural lighting, and lighting for public areas. Outdoor lighting design considers factors such as light pollution, energy efficiency, and environmental impact.

Output Ratio: A measure of the effectiveness of a lighting fixture’s design in delivering light from the lamp to the workspace or area to be illuminated. It’s calculated by comparing the total lumens emitted by the fixture to the lumens produced by the lamp alone.

Overcast Daylight: Natural light on an overcast day, which is generally diffused and even. In lighting design, simulating overcast daylight can create soft shadows and uniform illumination, often preferred in visual task areas for comfort and productivity.

Overhead Lighting: General lighting provided by fixtures mounted on the ceiling or high on the walls, offering broad illumination across an entire room or area. It forms the basis of most lighting schemes, complemented by task and accent lighting for full coverage.

Overlighting: The excessive use of artificial light beyond what is necessary for a task or space. Overlighting can lead to wasted energy, discomfort due to glare, and negative environmental impacts.

Parabolic Aluminized Reflector (PAR) Lamp: A type of light source that has a reflective parabolic mirror behind the lamp to direct the light. PAR lamps are used for their ability to produce a focused beam of light, making them suitable for spot and flood lighting applications.

Parasitic Power: The power consumed by a device when it is in standby mode but not actively in use. In lighting systems, minimizing parasitic power in controls and sensors is crucial for overall energy efficiency.

Passive Infrared Sensor (PIR): A sensor used in lighting control systems to detect motion based on changes in infrared radiation levels caused by moving objects. PIR sensors are widely used in security and energy-saving applications.

Pathway Lighting: Outdoor lighting designed to illuminate walkways, paths, and sidewalks, enhancing visibility and safety for pedestrians. Pathway lighting fixtures are often low to the ground and directed to minimize glare.

Patterned Shadows: Deliberate shadow effects created by blocking or filtering light through patterned screens, foliage, or other materials. This technique adds visual interest and dynamism to spaces through the interplay of light and shadow.

Pendant Light: A type of light fixture that hangs from the ceiling, suspended by a cord, chain, or metal rod. Pendant lights are versatile and used for task lighting over counters and tables, as well as for ambient or decorative lighting.

Pendant System: A lighting installation where fixtures are suspended from the ceiling, often used for task lighting over counters, dining areas, or as decorative focal points in a room.

Perimeter Lighting: Lighting installed along the edges or boundaries of a room or outdoor area. In interiors, it can enhance the sense of space and provide indirect lighting; outdoors, it enhances security and defines the area.

Phase-cut Dimming: A dimming technology for adjusting the brightness of light bulbs, including LEDs and incandescents, by cutting off a portion of the voltage waveform. Compatible dimmers can smoothly reduce lighting levels to create the desired ambiance.

Phosphor: A substance that emits light (phosphorescence) when exposed to light radiation. In lighting, phosphors are used on the inside surface of fluorescent and LED lamps to convert ultraviolet light into visible light, thereby determining the color temperature and color rendering properties of the light source.

Photobiomodulation: The use of light in specific regions of the electromagnetic spectrum to induce biological changes, beneficial for health. It’s explored in therapeutic settings and influences lighting design for wellness spaces.

Photocell: A sensor that detects light levels and controls lighting fixtures based on the amount of natural light present. Photocells are used in outdoor and street lighting systems to automatically turn lights on at dusk and off at dawn, conserving energy.

Photometrics: The study and measurement of light as it is perceived by the human eye. Photometric data, such as luminous flux, illuminance, luminance, and color rendering, are crucial for evaluating and planning lighting designs to ensure they meet specific needs and standards.

Photometry: The science of measuring visible light in terms of its perceived brightness to the human eye. Photometric data, such as luminous flux, illuminance, and luminance, are essential in evaluating and designing lighting systems.

Photopic Vision: The human eye’s response to light under well-lit conditions, primarily mediated by cone cells, which are sensitive to color. Lighting design for daytime and well-lit environments focuses on photopic vision.

Photosensor: A device that detects light levels and is used in lighting control systems to adjust artificial lighting based on the amount of natural daylight present. This contributes to energy savings and optimal lighting conditions throughout the day.

Photovoltaic (PV) Lighting: Lighting systems powered by solar panels that convert sunlight into electricity. PV lighting is sustainable and commonly used in outdoor and street lighting, reducing dependency on the electrical grid.

Plastic Optical Fiber (POF): A type of optical fiber made from plastic used to transmit light for illumination or data. In lighting, POF can be used for decorative effects, signage, or in areas where flexible, non-conductive light transmission is needed.

Plenum Space: In building construction, the space between the structural ceiling and a drop-down ceiling or under a raised floor. Lighting, heating, ventilation, and air conditioning (HVAC) components, and other utilities are often installed in the plenum space. The design and placement of lighting fixtures must consider access and integration within these spaces.

Plenum-rated: Refers to cables and materials that are certified to be installed in the plenum spaces of buildings due to their low smoke and fire propagation characteristics. In lighting, using plenum-rated components ensures compliance with building codes and safety standards.

Polarized Light: Light waves that oscillate in a single plane. Polarized lighting can reduce glare and improve visual clarity in certain applications, such as photography, aviation, and display technologies.

Pole Light: An outdoor lighting fixture mounted on a pole, used to illuminate streets, parking lots, pathways, and public spaces. Pole lights contribute to safety and security by providing visibility at night.

Polycarbonate Diffuser: A durable, translucent cover for lighting fixtures made from polycarbonate material. These diffusers spread light evenly, reduce glare, and protect the light source from environmental factors.

Post-top Luminaire: A lighting fixture designed to mount on top of a pole, commonly used in street lighting, parks, and garden pathways. These luminaires contribute to aesthetics and functionality of outdoor spaces.

Power Factor: A measure of how effectively electrical power is converted into useful light output in a lighting system. It is the ratio of the real power flowing to the load to the apparent power in the circuit. High power factor lighting equipment is more energy efficient.

Primary Optics: In LED lighting, the first set of optical components (lenses, reflectors) directly attached to or integrated with the LED chip to shape its initial light output. Primary optics are crucial for directing light efficiently and achieving the desired beam pattern.

Prismatic Lens: A lens featuring a surface patterned with prisms, designed to distribute light evenly and reduce glare. Prismatic lenses are common in office and industrial lighting fixtures for comfortable, efficient illumination.

Programmable Lighting: Lighting systems that can be programmed to change intensity, color temperature, and sometimes color, according to schedules or in response to sensors. Programmable lighting enhances energy efficiency and can improve comfort and productivity.

Projection Lighting: A lighting technique that uses specialized fixtures to project patterns, images, or colors onto surfaces or spaces for decorative or thematic effects. It can transform the ambiance of a venue or highlight architectural features.

Puck Light: A small, round, and usually LED light that can be surface mounted or recessed. Puck lights are versatile and used for under-cabinet lighting, display cases, and as accent lighting to illuminate specific areas or objects.

Pulse Width Modulation (PWM): A technique used to adjust the brightness of LED lights by varying the duty cycle of the electrical power supplied to them. PWM allows for precise control over light intensity without changing the color temperature of the LEDs.

Quad Tube Fluorescent: A compact fluorescent lamp (CFL) design featuring four tubular loops connected to a single base. Quad tube fluorescents offer higher light output in a compact form, making them suitable for spaces requiring efficient, space-saving lighting solutions.

Qualified Lighting Professional: An individual with recognized qualifications and expertise in the field of lighting design, installation, or maintenance. Qualified professionals ensure that lighting systems meet industry standards, are energy-efficient, and fulfill the intended design objectives.

Quality Assurance in Lighting: The process of ensuring that lighting products and systems meet specified standards for performance, safety, and reliability. Quality assurance involves testing, certification, and ongoing monitoring to maintain high standards across the lighting industry.

Quality of Light: Refers to various attributes of lighting that affect visual perception and comfort, including color temperature, color rendering, brightness, uniformity, and absence of flicker or glare. High-quality lighting enhances the functionality, aesthetics, and emotional impact of spaces.

Quantum Dots: Nanoscale semiconductor particles that can emit light of specific wavelengths when excited by an external light source. In lighting, quantum dots are used to enhance color rendering and efficiency, particularly in LED and display technologies.

Quarry Lighting: Lighting designed for harsh, industrial environments such as quarries and mines. Quarry lighting must be durable, weather-resistant, and capable of providing high levels of illumination for safety and operational efficiency.

Quartic Lens: A type of optical lens with a surface curvature designed to distribute light in specific patterns, used in some lighting fixtures to control beam spread and reduce glare. Quartic lenses can enhance the precision of light distribution for targeted illumination.

Quartz Halogen: A type of incandescent lamp that uses a filament encased in a quartz envelope filled with halogen gas, improving efficiency and lifespan compared to traditional incandescent bulbs. Quartz halogen lamps provide bright, white light and are used in various applications, from residential to theatrical lighting.

Quartz Restrike: In HID lighting, a restrike system that uses a small quartz auxiliary lamp to provide immediate illumination while the main lamp cools down and re-ignites. This feature reduces downtime and improves convenience in applications where continuous lighting is critical.

Quick-Connect System: A feature in some lighting fixtures and accessories that allows for easy and secure electrical connections without the need for tools or extensive wiring. This system simplifies installation and maintenance, making it user-friendly for both professionals and DIYers.

Quiescent Current: The minimal amount of current that flows through an electronic device, such as a lighting control system, when it is powered but not actively in use. Minimizing quiescent current is essential for energy-saving in lighting applications.

RGB (Red, Green, Blue): Refers to a color model used in lighting and display technologies where lights of these three colors are combined in various ways to produce a broad array of colors. RGB lighting systems can create dynamic, colorful lighting effects for both functional and aesthetic purposes.

RGB Lighting: Stands for Red, Green, Blue lighting, which refers to LED lighting systems capable of producing a wide range of colors by mixing these three primary colors. RGB lighting is used for dynamic and decorative lighting applications, allowing for color changes and effects.

RGBW: Refers to LED lighting that combines red, green, blue, and white LEDs. RGBW allows for a broader color palette and the ability to produce pure white light, offering more versatility than RGB for both mood lighting and functional illumination.

Radiant Efficiency: The ratio of the power emitted as radiation (light) by a light source to the total power consumed by the source. Higher radiant efficiency indicates a more efficient conversion of electrical energy into visible light.

Radiant Flux: The total amount of electromagnetic energy emitted by a light source per unit of time, measured in watts (W). It encompasses all energy emitted across the electromagnetic spectrum, not just visible light.

Radioluminescence: The phenomenon where certain materials emit light when exposed to ionizing radiation. While not commonly used for general lighting, radioluminescent materials can be found in specialized applications such as emergency signage and instrument dials.

Rake Lighting: A lighting technique where light is angled to cast shadows and highlight textures or features on a surface, creating a dramatic effect. It is often used in architectural lighting to emphasize material qualities or in theater to add depth to stage designs.

Rated Life: The average lifespan of a light source, typically given in hours, based on manufacturer testing and industry standards. The rated life is an estimate of when 50% of a large group of identical lamps will have failed.

Rated Lumens: The initial light output of a lamp or luminaire, as specified by the manufacturer. Rated lumens provide a baseline for comparing the brightness of different lighting products under standardized conditions.

Ray Tracing: A technique used in lighting design and simulation to model the path of light rays as they travel through spaces and interact with surfaces. This method helps designers predict lighting levels and effects, ensuring the intended outcome for the illuminated space.

Reactive Power: In electrical systems, power that does not do useful work but is necessary for creating magnetic fields to transmit active power. In lighting, especially with inductive loads like magnetic ballasts, managing reactive power is important for system efficiency.

Recess Depth: In recessed lighting, the distance from the opening of the fixture to the position of the light source within the housing. Proper recess depth can influence the distribution of light and the appearance of glare.

Recessed Lighting: A type of lighting fixture installed into a hollow opening in a ceiling. Also known as can lights or downlights, recessed lighting is used to provide ambient, task, or accent lighting without the fixture itself being prominently visible.

Recessed Troffer: A type of lighting fixture designed for installation in the recessed openings of suspended ceilings. Troffers are commonly used in commercial and office settings, providing diffuse, overhead lighting that evenly illuminates large areas.

Reflectance: The ratio of reflected light to incident light on a surface. Reflectance values, measured as a percentage, are used in lighting calculations to determine how much light will be reflected by walls, ceilings, and floors, affecting the overall brightness of a space.

Reflector: A component of a lighting fixture designed to redirect light from the source, typically using a mirrored, metallic, or reflective surface to direct light where needed and improve efficiency.

Remote Phosphor: A technology used in some LED lighting systems where a phosphor layer is placed away from the LED chip. Light from the blue LEDs strikes the remote phosphor, causing it to emit white light. This approach can improve color consistency and efficiency.

Remote-Controlled Lighting: Lighting systems that can be operated via remote control, allowing users to adjust brightness, color temperature, and sometimes color without physically interacting with the switch or fixture. This adds convenience and accessibility to lighting control.

Retrofit: The process of updating older lighting systems with newer technology, such as replacing incandescent lamps with LED lamps or upgrading to more efficient fixtures. Retrofitting is often undertaken to improve energy efficiency, reduce maintenance costs, and enhance light quality.

Retrofit Kit: A set of components designed to convert existing lighting fixtures to accommodate newer, more efficient light sources or technologies without replacing the entire fixture. Retrofitting is a cost-effective way to upgrade lighting systems for energy savings and improved performance.

Retrofit Luminaire: A lighting fixture specifically designed or adapted to replace existing fixtures with a more energy-efficient solution, often involving LED technology. Retrofit luminaires are designed to fit into the existing installation with minimal modifications.

Retrofitting: The process of upgrading existing lighting systems with new technology or fixtures to improve energy efficiency, reduce maintenance costs, or enhance lighting quality. Retrofitting often involves replacing lamps, ballasts, or adding controls.

Reveal: Architectural feature used in lighting to create a slot or recess in a wall or ceiling from which indirect lighting can be cast. Reveals can enhance the architectural lines of a space and provide a hidden source of illumination.

Ripple Control: A method used in some electrical utilities to control the load on the network by sending signals through the power lines. In lighting, this can affect the operation of lights, potentially causing flicker or dimming, and is a consideration in designing systems that minimize interference.

Rise Time: The time it takes for a light source, particularly LEDs, to reach a specified level of brightness from the moment it is turned on. Faster rise times are generally preferable for applications requiring instant illumination.

Roadway Lighting: Lighting designed to illuminate streets, highways, and other roadways, enhancing visibility and safety for drivers, cyclists, and pedestrians. Proper roadway lighting reduces accidents and improves traffic flow.

Room Cavity Ratio (RCR): A calculation used in lighting design to estimate the efficiency of light distribution in a room. It considers the room dimensions and reflectance of surfaces to help determine the appropriate number and placement of light fixtures.

Rotary Dimmer: A type of dimmer switch that adjusts light levels through a rotary knob. Rotary dimmers offer a simple and intuitive way to control the brightness of lighting fixtures, suitable for a wide range of residential and commercial applications.

Rough Service Lamp: A durable, resilient light bulb designed to withstand vibration, shock, or rough handling better than standard bulbs. These lamps are suited for challenging environments, such as workshops, factories, and outdoor areas.

Saturation: In terms of lighting and color, saturation refers to the intensity of a color in the light spectrum. Highly saturated colors appear vivid and rich, while low saturation results in more muted tones. Adjustable lighting systems can modify saturation for various effects.

Scenic Lighting: The use of lighting in theatrical, film, and television production to create mood, focus attention, and support the storytelling. Scenic lighting involves carefully planned combinations of color, intensity, and direction.

Sconce: A type of wall-mounted lighting fixture used for ambient, task, or accent lighting. Sconces can provide directional lighting or diffuse light throughout a space and are commonly used in hallways, bedrooms, and living areas.

Scotopic Vision: The human eye’s ability to see in low-light conditions, primarily using rod cells. Scotopic vision is sensitive to wavelengths near the blue-green spectrum, influencing how lighting is perceived in dim environments and the design of lighting for night-time use.

Sensor Lighting: Lighting systems that incorporate sensors to detect presence, motion, daylight, or other environmental conditions, automatically adjusting lighting based on real-time data to optimize energy use and comfort.

Series Circuit: An electrical circuit in which the components are connected end-to-end so that the current flows through each component in sequence. In lighting, series circuits can be used in string lights and some types of LED arrays, where the failure of one light can affect the entire circuit.

Shade: A component of a lighting fixture that covers the light source, directing light output and reducing glare. Shades can be made from a variety of materials, including glass, fabric, and metal, and contribute to the aesthetic of the fixture.

Shadowing: The intentional use of shadows created by lighting to enhance or emphasize the three-dimensional form of objects or spaces. Effective shadowing can add depth and interest to lighting designs.

Silhouette Lighting: A lighting technique where the light source is positioned behind the subject, creating a silhouette effect by outlining the subject against a lighter background. This technique can produce dramatic and artistic lighting effects.

Smart Bulb: An LED bulb equipped with technology that allows it to be controlled remotely via apps or smart home systems. Smart bulbs can adjust brightness, color temperature, and sometimes color, offering versatile lighting options for different needs and preferences.

Smart Lighting: Lighting systems equipped with technology that allows them to be controlled remotely via smartphones, tablets, or voice-activated home automation systems. Smart lighting offers functionalities like dimming, color changing, scheduling, and integration with other smart home devices.

Soffit Light: Similar to soffit lighting, these are fixtures installed in the soffit (the underside of architectural features like eaves or overhangs) to illuminate the exterior of a building or the ceiling of an interior space, often providing indirect lighting that enhances architectural details.

Soft Light: Lighting that produces a diffused illumination, reducing harsh shadows and creating a gentle, even light. Soft light is often preferred for its flattering qualities and the comfortable visual environment it creates.

Spectral Distribution: A representation of the range of wavelengths (colors) emitted by a light source. Understanding a light source’s spectral distribution is crucial for applications requiring precise color rendering and for maximizing visual comfort and health.

Spectral Power Distribution (SPD): A detailed plot or graph that shows the intensity of light emitted by a source across different wavelengths. SPD is key for analyzing the color characteristics and efficiency of light sources.

Spectral Tuning: Adjusting the output of a light source across different wavelengths to achieve specific lighting effects or to meet particular needs, such as enhancing plant growth, improving visual comfort, or supporting human circadian rhythms.

Specular Reflection: A reflection from a smooth surface where the angle of reflection equals the angle of incidence, similar to how a mirror reflects light. In lighting design, controlling specular reflection is important to reduce glare and improve visibility.

Spike Light: A type of outdoor light fixture mounted on a spike, which is pushed into the ground. Spike lights are often used for landscape lighting, illuminating pathways, plants, or architectural features from the ground up.

Spill Light: Unwanted light that escapes from a fixture and illuminates areas not intended to be lit, which can cause glare or contribute to light pollution. Effective lighting design seeks to minimize spill light through precise aiming and the use of shields or baffles.

Spotlight: A light fixture designed to focus light on a specific area or object, creating a concentrated beam of light. Spotlights are used for accent lighting, task lighting, or to highlight architectural features or artwork.

Spread Light: Fixtures designed to cast a wide, diffuse beam of light, covering a broad area with uniform illumination. Spread lights are often used in landscape lighting to softly illuminate large areas without creating harsh shadows.

Stair Lighting: Lighting designed specifically for staircases, including step lights, handrail lights, and overhead fixtures, to ensure safety by providing clear visibility of each step and contributing to the overall lighting design of a space.

Step Light: A small, low-level lighting fixture installed in or near steps or staircases to provide illumination for safety. Step lights help prevent accidents by clearly marking each step’s edge in low-light conditions.

Strobe Lighting: A lighting effect that produces bright, flashing light at regular or irregular intervals. Strobe lights are used for special effects in entertainment, as warning signals, and for scientific and industrial applications.

Sun Tunnel: A tubular device used to channel natural sunlight from the roof into interior spaces, providing daylighting to areas that may not have direct access to windows. Sun tunnels enhance indoor lighting with minimal heat gain or loss.

Supplementary Lighting: Additional lighting provided to supplement the primary lighting system, often used to enhance illumination levels for specific tasks or to highlight decorative elements or architectural features.

Surface-Mounted Light: A lighting fixture that is attached directly to the surface of a ceiling or wall, as opposed to being recessed or suspended. Surface-mounted lights are versatile and can be used in various applications where space is limited or where direct installation is preferred.

Suspended Lighting: Light fixtures that are hung from the ceiling by cables, rods, or chains, allowing for flexible placement and the creation of visual interest at different heights. Suspended lighting can include pendants, chandeliers, and linear fixtures.

Sustainability: In the context of lighting design, sustainability refers to practices and products that reduce environmental impact. This includes using energy-efficient light sources, minimizing light pollution, and selecting materials and systems with lower ecological footprints.

Switchgear: The collective term for the electrical components used to control, protect, and isolate electrical equipment. In lighting systems, switchgear can include switches, dimmers, and circuit breakers that allow for the safe and efficient control of lighting.

Symmetrical Lighting: A lighting layout where fixtures are placed in a symmetrical pattern, providing uniform illumination and a balanced aesthetic. This approach is often used in formal settings and spaces where even lighting is crucial.

System Efficacy: The overall efficiency of a lighting system, measured as the ratio of total luminous flux (in lumens) emitted by the system to the total power consumption (in watts). System efficacy takes into account not only the efficiency of the light sources but also the impact of the luminaire design and controls on the overall performance of the lighting system.

T5, T8, T12 Lamps: Types of fluorescent tubes distinguished by their diameter. T5 lamps are about 5/8 inch in diameter, T8s are 1 inch, and T12s are 1.5 inches. The size affects the lamp’s efficiency, light output, and application.

Table Lamp: A portable lighting fixture designed to stand on a table or desk, providing task or ambient lighting. Table lamps come in a variety of styles and are often used in living rooms, bedrooms, and offices for both functionality and decoration.

Task Contrast: The visual contrast between a task area and its immediate surroundings. Proper task contrast is important for reducing eye strain and improving visibility, especially in workspaces where detailed or concentrated activities are performed.

Task Layering: The practice of layering multiple sources of task lighting to achieve optimal illumination for specific activities, ensuring that light is evenly distributed and minimizing glare and shadows.

Task Lighting: Lighting that is specifically designed to illuminate a particular area where a task is performed, enhancing visibility and reducing eye strain. Task lighting is typically more focused and brighter than ambient lighting and can include desk lamps, under-cabinet lights, and reading lamps.

Task-Ambient Lighting: A lighting strategy that combines direct task lighting with indirect ambient lighting to create a balanced and visually comfortable environment, ideally suited for workplaces and study areas.

Temporal Light Modulation (TLM): Variations in light intensity over time, which can include flicker or stroboscopic effects. Managing TLM is important for visual comfort and reducing the risk of photosensitive reactions among some individuals.

Tertiary Optics: Additional optical components used in lighting fixtures to further refine or alter the distribution of light from primary and secondary optics, such as diffusers or films that spread light more evenly or reduce glare.

Theatrical Lighting: Specialized lighting used in theater, dance, concerts, and other performances to enhance the visual impact of the production, create mood, and focus audience attention. Theatrical lighting involves a combination of techniques and equipment, including spotlights, color gels, and gobos.

Thermal Management: The process of controlling the temperature of a lighting system, particularly LED systems, to maintain optimal performance and extend the life of the light source. Effective thermal management is crucial because excessive heat can degrade the quality of light and shorten the lifespan of LEDs.

Thermoluminescence: The property of some materials to emit light when heated. While not directly related to everyday lighting design, thermoluminescence is used in archaeological and geological dating, indicating past exposure to sunlight or heat.

Tint: In the context of lighting, tint can refer to the addition of a hue to white light, altering its color perception. Lights with tints can influence the mood and aesthetic of a space.

Tint Control: The ability to adjust the hue of light emitted by a fixture, often found in LED systems. Tint control allows for dynamic changes in lighting color for aesthetic or functional purposes, enhancing the versatility of lighting designs.

Tinted Glass: Glass that has been colored or treated to reduce transmittance or alter the color of the light passing through it. Tinted glass in lighting fixtures can create atmospheric effects or reduce glare.

Torchiere: A type of floor lamp that directs light upward to illuminate a room indirectly. The torchiere lamp’s bowl-shaped shade reflects light off the ceiling, providing a soft, diffused light source.

Total Harmonic Distortion (THD): A measure of the distortion of an electrical signal in lighting systems, particularly those with electronic ballasts or drivers. Lower THD values indicate cleaner power and reduced risk of interference with other electronic devices.

Track Lighting: A lighting system where light fixtures are mounted on a continuous track containing electrical conductors. This allows for flexible positioning of lights, making it ideal for accent, task, and ambient lighting in both residential and commercial settings.

Transformers: Devices that transfer electrical energy between two or more circuits through electromagnetic induction. In lighting, transformers are used to step down voltage for low-voltage lighting systems, such as halogen or certain LED lights.

Transient Protection: Measures and devices used to protect lighting systems from transient voltage spikes or surges, which can damage electronic components. Effective transient protection is crucial for the longevity and reliability of modern lighting installations.

Translucency: The quality of a material that allows light to pass through diffusely, but not clearly enough to perceive distinct images. Translucent materials in lighting fixtures can soften light and reduce glare, creating a more comfortable ambiance.

Transmittance: The measure of the amount of light that passes through a material. In lighting design, materials with high transmittance are chosen for lenses and diffusers to maximize the efficiency of light output.

Triac Dimmer: A type of dimmer switch that controls light levels using a TRIode for Alternating Current (TRIAC) semiconductor device. Triac dimmers are commonly used with incandescent and compatible LED lighting to adjust brightness.

Trim: The visible part of a recessed lighting fixture that frames the hole in the ceiling and holds the lamp or bulb. Trims can vary in style and finish, contributing to the fixture’s aesthetic and the quality of light distribution.

Trimless Recessed Lighting: Recessed lighting fixtures designed without visible trim, creating a seamless appearance where the light source blends into the ceiling. Trimless designs are often used in modern and minimalist interiors for their clean, architectural look.

Troffer: A rectangular light fixture that is recessed into a ceiling grid, commonly used in commercial and institutional settings for ambient lighting. Troffers are designed to fit into standard drop ceiling grids and are available in various sizes, typically accommodating fluorescent or LED light sources.

Trough Lighting: A type of lighting where fixtures are installed in a long, continuous channel or trough, often used for indirect lighting along walls or ceilings to create a uniform light distribution without harsh shadows.

Tunable Spectrum: Lighting systems that offer control over the spectral output, allowing users to adjust not just the color temperature but also the relative intensities of different wavelengths. Tunable spectrum lighting can support plant growth, enhance visual perception, and influence mood and circadian rhythms.

Tunable White: A feature in LED lighting that allows users to adjust the color temperature of the light from warm to cool whites, simulating the natural progression of daylight throughout the day. This can enhance comfort and support circadian rhythms.

U-Shaped Fluorescent Tubes: A variant of fluorescent tube lights bent into a U-shape, designed to fit in more compact fixtures. These tubes offer the benefits of fluorescent lighting, such as efficiency and long life, in spaces where traditional linear tubes might not fit.

UL Listing (Underwriters Laboratories): A certification given to electrical devices that meet stringent safety standards. Lighting fixtures and components with UL listing have been tested for safety risks such as fire, electric shock, and related hazards.

UV Filtering: The process or feature of reducing or blocking the transmission of ultraviolet (UV) light through a medium. In lighting, UV filtering is important for protecting artworks, fabrics, and sensitive materials from fading or degradation caused by exposure to UV light.

UV Filtering Glass: Glass that has been treated or coated to block ultraviolet (UV) rays. In lighting fixtures, UV filtering glass is used to protect objects from potential UV damage, making it ideal for museums, art galleries, and retail displays where sensitive items are illuminated.

UV LEDs: Light Emitting Diodes that produce ultraviolet light. UV LEDs have applications in various fields, including medical treatment, disinfection, curing processes in industrial settings, and forensic analysis. Their efficiency and compact size make them increasingly popular for specialized lighting needs.

UV Radiation in Lighting: The component of light that is in the ultraviolet spectrum. While most visible light sources emit minimal UV radiation, some lighting applications, like curing or disinfection, specifically utilize UV light for its unique properties.

Ultraviolet Curing: A process that uses UV light to quickly dry or cure inks, coatings, adhesives, and other materials. In lighting design, UV curing systems are carefully engineered to deliver the precise intensity and spectral output required for efficient curing.

Umbra: The darkest part of a shadow where the light source is completely blocked by an object. Understanding the umbra and penumbra (the partially shaded outer region) can be important in theatrical lighting and creating mood in various spaces.

Under-cabinet Lighting: Lighting installed underneath cabinets, particularly in kitchens, to provide task lighting on countertops. This lighting adds functionality by illuminating workspaces without casting shadows and can also serve as ambient lighting.

Underpass Lighting: Lighting specifically designed for tunnels, underpasses, and similar structures to ensure safe passage for vehicles and pedestrians. Adequate underpass lighting addresses challenges such as transitioning from daylight to artificial light and minimizing glare.

Underwater Lighting: Lighting solutions designed to operate safely and effectively underwater, such as in pools, fountains, and ponds. These lights not only enhance safety by improving visibility but also add aesthetic appeal to water features.

Unified Glare Rating (UGR): A numerical way of evaluating how likely a lighting system is to cause discomfort to those within the environment. It helps designers create spaces that minimize the risk of glare, which is crucial for office settings and areas requiring concentrated work.

Uniformity Ratio: The measure of how evenly light is distributed across a given area, typically expressed as the ratio of the minimum to the average illuminance levels. High uniformity ratios indicate more even lighting, which can improve visual comfort and reduce glare.

Uninterruptible Power Supply (UPS) for Lighting: A backup power system that provides emergency power to lighting fixtures in the event of a main power failure. UPS systems ensure continuous lighting, which is crucial for safety in commercial buildings, hospitals, and other critical environments.

Universal Ballast: A type of ballast designed to operate with a wide range of lamp types and voltages. Universal ballasts provide flexibility in lighting design and retrofit projects by accommodating various lighting fixtures without the need for multiple specific ballasts.

Up/Down Lighting: A lighting fixture design that emits light both upwards and downwards, creating a balanced illumination and visual interest on the surfaces above and below the fixture. This type of lighting is popular for wall sconces in corridors and public areas.

Upgraded Lighting System: Refers to an existing lighting system that has been enhanced or replaced with newer, more efficient technology, such as LED lighting. Upgrades are often undertaken to reduce energy consumption, improve light quality, and decrease maintenance costs.

Uplight: Lighting that is directed upwards towards the ceiling or sky, often used for architectural lighting or in landscape design to highlight trees, sculptures, and other features. Uplight can create a dramatic and inviting atmosphere in both indoor and outdoor spaces.

Uplighting: A lighting technique where light is directed upwards to illuminate the ceiling or upper walls of a space. Uplighting can create a sense of openness and height, and is often used for dramatic effect or to highlight architectural features.

Usability in Lighting Design: Refers to how user-friendly and accessible a lighting system is, including the ease of controlling light levels, color temperature, and other features. Good usability in lighting design enhances the overall experience and satisfaction of the occupants.

User Interface for Lighting Control: The component of a lighting system that allows users to interact with and control the lighting. This can range from traditional switches and dimmers to advanced digital interfaces on smartphones or tablets for smart lighting systems.

User-Centric Lighting Design: An approach to lighting design that prioritizes the needs, comfort, and well-being of the people using the space. This involves considering factors like task requirements, visual comfort, aesthetics, and the psychological impact of lighting.

Utilitarian Lighting: Lighting that is designed primarily for function rather than aesthetic appeal. Utilitarian lighting focuses on providing the necessary illumination for tasks or safety, often seen in industrial, commercial, and certain outdoor applications.

Utility Lighting: Similar to utilitarian lighting, this refers to lighting that serves a basic need for illumination with an emphasis on functionality. Utility lighting is straightforward, often cost-effective, and is focused on providing adequate visibility for safety and tasks.

Utility Rebate Programs for Lighting: Incentive programs offered by utility companies to encourage the adoption of energy-efficient lighting technologies. Rebates can significantly lower the cost of upgrading to more efficient lighting systems, promoting energy conservation and cost savings for consumers.

Utilization Factor (UF): A measure that describes the efficiency with which light emitted from a lighting fixture is distributed or utilized in the intended area. It takes into account the layout of the space, reflectance of surfaces, and the fixture’s light distribution characteristics to evaluate how effectively the light serves the intended purpose.

Value in Lighting: Refers to the lightness or darkness of a color, which can be influenced by the intensity and quality of lighting. Understanding value is important in lighting design to achieve the desired mood and atmosphere, as well as to enhance the perception of space and materials.

Vandal-Resistant Lighting: Fixtures designed to withstand tampering or damage, typically used in public or exposed areas where security is a concern. These fixtures are made from durable materials and often have features like tamper-proof screws and reinforced enclosures.

Vanity Lighting: Lighting fixtures designed specifically for use in bathroom vanities, providing illumination for grooming tasks. Vanity lighting is typically positioned to minimize shadows on the face, ensuring even, flattering light.

Vaportight Fixture: Lighting fixtures sealed against moisture and vapors, making them suitable for use in wet or damp locations, such as industrial settings, bathrooms, or outdoor areas. Vaportight fixtures protect the electrical components and lamp from exposure to adverse conditions.

Variable Color Temperature: Lighting that allows adjustment of color temperature from warm to cool whites. This feature enables users to change the lighting atmosphere according to the time of day, activity, or personal preference, enhancing comfort and functionality.

Veiling Reflections: Unwanted reflections on surfaces like computer screens or glossy materials that can obscure detail and cause visual discomfort. Lighting design aims to minimize veiling reflections through careful placement of light sources and consideration of surface properties.

Ventilation in Lighting Fixtures: Refers to the design features in lighting fixtures that allow for air flow to help dissipate heat generated by the light source. Effective ventilation is crucial for maintaining the optimal operating temperature and extending the lifespan of lighting components, especially in high-intensity or enclosed fixtures.

Vibration-Resistant Lighting: Fixtures and bulbs designed to withstand vibrations without loss of performance or structural integrity. This type of lighting is essential in industrial settings, transportation applications, and areas subject to frequent movement or shock.

Vibration-Resistant Lighting: Fixtures and bulbs designed to withstand vibrations without loss of performance or structural integrity. This type of lighting is essential in industrial settings, transportation applications, and areas subject to frequent movement or shock.

Viewing Angle: The maximum angle at which a light source or fixture can be viewed without significant loss of visual performance or appearance. In LED lighting, the viewing angle is determined by the design of the LED chip and any optical components, such as lenses or diffusers, affecting how light is distributed in a space.

Vintage Lighting: Lighting fixtures or styles that evoke a sense of history or nostalgia, often replicating designs from specific eras. Vintage lighting can add character and warmth to a space, blending modern functionality with classic aesthetics.

Virtual Filament LED: An LED technology designed to mimic the appearance of traditional incandescent filament bulbs, combining the energy efficiency and longevity of LEDs with the classic aesthetic of incandescent lighting.

Visual Acuity: The clarity or sharpness of vision, which can be significantly affected by the quality and quantity of lighting. Proper lighting design considers visual acuity requirements for various tasks and environments to ensure that lighting supports the ability to see details clearly and comfortably.

Visual Comfort: The creation of lighting conditions that are comfortable for the eye, without causing glare or excessive contrast. Achieving visual comfort is a primary objective in residential, workplace, and public space lighting design.

Visual Comfort Probability (VCP): A metric that measures the likelihood that a lighting system will produce comfortable visual conditions, minimizing glare and optimizing light distribution. High VCP values indicate lighting designs that are less likely to cause discomfort to the majority of occupants.

Visual Ergonomics: The study and application of lighting design principles to create environments that support human visual performance and comfort, reducing eye strain and fatigue. Visual ergonomics is crucial in workplaces, educational settings, and anywhere tasks require sustained visual attention.

Visual Field: The entire area that can be seen at a given moment without moving the eyes. Lighting design can influence how the visual field is perceived, emphasizing certain areas or features, and contributing to the overall spatial experience.

Visual Interest: In lighting design, visual interest refers to the creation of focal points or areas within a space that attract the viewer’s eye, contributing to the overall aesthetic and dynamic of the environment. Lighting can create visual interest through contrast, color, texture, and pattern, enhancing the space’s appeal and functionality.

Visual Light Communication (VLC): A technology that uses light from LEDs to transmit data. In lighting design, VLC can be implemented for innovative applications such as indoor positioning systems and smart lighting solutions, where lights not only illuminate spaces but also communicate information.

Visual Perception: The process by which the brain interprets and makes sense of visual stimuli received from the environment. Lighting design plays a significant role in influencing visual perception by affecting how colors, textures, and spatial relationships are seen and understood.

Visual Rendering Index (VRI): An alternative term sometimes used for Color Rendering Index (CRI), which measures the ability of a light source to accurately reproduce colors in comparison to a natural light source. High VRI or CRI values are desirable for applications where color fidelity is important.

Visual Task Area: The specific area where visual activities occur, requiring adequate illumination for tasks such as reading, cooking, or working. Lighting design focuses on providing sufficient, targeted light to visual task areas without causing glare or shadows.

Vividness: A lighting quality that enhances the saturation and brightness of colors, making them appear more vibrant. Lighting with high vividness can make environments and objects more engaging and visually appealing.

Volt: The unit of measurement for electrical potential difference or electromotive force. In lighting, the voltage of a power supply and the voltage requirements of lighting fixtures must be compatible to ensure safe and efficient operation.

Volt-Ampere (VA): A unit of measurement used to describe the apparent power in an electrical circuit, considering both the voltage and current. In lighting, the VA rating of fixtures and systems helps in planning the electrical load and ensuring compatibility with power supplies.

Voltage Drop: The reduction in voltage in an electrical circuit between the power source and the device it powers, which can occur over long distances or with thin wires. In lighting, significant voltage drops can lead to dimmer lights and inefficiency, especially in low-voltage lighting systems like LED strips.

Voltage Regulation: The ability of a power supply system to maintain a constant voltage level to lighting fixtures despite fluctuations in the load or power supply. Good voltage regulation is essential for ensuring consistent lighting performance and preventing damage to sensitive lighting equipment.

Volume Lighting: A design approach that considers the illumination of three-dimensional space rather than just focusing on surfaces. Volume lighting ensures that environments are evenly lit, enhancing spatial understanding and comfort.

Volumetric Lighting: A lighting strategy that illuminates an entire space evenly, filling the volume of the room with light rather than focusing solely on horizontal surfaces like floors and tables. This approach can improve the overall ambiance of a space and enhance visual comfort.

Wall Grazing: Similar to wall washing, wall grazing is a lighting technique that aims to highlight the texture of a surface (e.g., brick, stone, or fabric wall coverings) by placing light fixtures close to the surface and directing light at a narrow angle. This approach creates dramatic shadows and enhances the three-dimensional qualities of the surface.

Wall Washing: A lighting technique used to evenly illuminate a vertical surface, such as a wall, with soft, diffuse light. Wall washing minimizes shadows and highlights the texture or color of the wall surface, often used in galleries, museums, and residential spaces to enhance the perception of space and height.

Warm White: A description of the color temperature of light, typically around 2700K to 3000K on the Kelvin scale, which emits a warm, yellowish glow. Warm white lighting is often used in residential and hospitality settings to create a cozy, inviting atmosphere.

Watt (W): The unit of measure for electrical power. In the context of lighting, it quantifies the amount of energy a light source consumes. As energy efficiency becomes more critical, understanding the wattage of lighting fixtures is essential for managing energy consumption and operational costs.

Wavelength: The distance between successive peaks of a wave, such as light or sound. In lighting, wavelength is important for understanding the color of light produced by a source, as different wavelengths correspond to different colors perceived by the human eye.

Wiring Diagram: A schematic representation showing the components and connections of an electrical circuit, including lighting fixtures, switches, and power sources. Wiring diagrams are crucial for planning and installing lighting systems to ensure they function correctly and comply with electrical codes.

Workplane: The surface or area where tasks are performed, and adequate illumination is required for visual tasks. In an office, the workplane might be the top of a desk, while in a kitchen, it could be the countertop. Lighting design aims to provide sufficient, evenly distributed light on the workplane for comfort and efficiency.

Xenon Lamp: A type of gas discharge lamp that uses xenon gas to produce light. Xenon lamps are known for their high light output and color rendering capabilities. They are used in a variety of applications, including automotive headlights, cinema projectors, and searchlights. Unlike other discharge lamps, xenon lamps do not require time to warm up, providing immediate high-intensity light.

Yoke: In lighting design, especially in stage and architectural lighting, a yoke is the mechanical bracket that allows a lighting fixture to be mounted and oriented in various positions. The yoke enables the fixture to tilt up and down or rotate side to side, facilitating precise control over the direction of the light beam.

Zigbee: A specification for a suite of high-level communication protocols using small, low-power digital radios based on the IEEE 802.15.4 standard for wireless personal area networks (WPANs). In lighting design, Zigbee technology is often used for wireless control of lighting systems, enabling smart lighting solutions that can be remotely controlled and integrated into home automation systems.

Zonal Cavity Method: A technique used in lighting calculation to estimate the average illuminance on a workplane or surface within an interior space. The method takes into account the room geometry, reflectances of surfaces (ceiling, walls, and floor), and the luminaire’s photometric characteristics. It is a useful tool for lighting designers to ensure that planned lighting meets specific illuminance requirements.

Zone Lighting Control: A lighting control strategy that divides a space into zones, each of which can be independently controlled in terms of lighting levels, color temperature, and on/off states. Zone lighting control allows for more flexibility and efficiency in managing lighting according to different needs or activities within a space. It is often used in combination with occupancy sensors, timers, and daylight harvesting systems to optimize energy usage.

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