Bi-Level Control Device that controls light source intensity at two discrete levels in addition to off. Bollards Lights mounted on short, heavy piers, or posts. They are used mostly for larger residences and campus settings. Canopy Lighting Recessed or surface-mounted lighting on the underside of a covered drive-through, covered walkway, or covered gasoline pumping station. Color Rendering Index (CRI) A rating index commonly used to represent how well a light source renders the colors of objects that it illuminates. The maximum value of 100 indicates that the colors of objects can be expected to be seen as they would appear under an incandescent or natural daylight. Sources with CRI values less than 50 are generally regarded as Control of a light source’s intensity to practically any value within a given operating range. Correlated Color Temperature (CCT) A measure of the color appearance of a light source relative to a black body at a particular temperature expressed in degrees Kelvin (K). Incandescent lights have a low color temperature (approxi- mately 2,700K) and have a red-yellowish tone; daylight has a high color temperature (approximately 5,000K) and appears bluish (fluorescent Cool White is rated at 4,100K). Cove Lighting rendering colors poorly. Continuous Dimming Light built into a cove, a shelf, or ledge at the upper part of a wall, to illuminate the ceiling and upper wall area. Daylight Sensor A device that senses the amount of daylight in a room and adjusts the electric lighting accordingly. DesignLights Consortium® (DLC) The DesignLights Consortium (DLC) is an initiative of Efficiency Forward, Inc. As an independent non-profit organization, the DLC provides decision makers with data and resources on quality lighting, controls, and integrated building systems to reduce energy, carbon, and light pollution. Diffuser Light control device that spreads light by scattering it. Dimmer Control that varies the output of the light source by reducing the voltage or current to the lamp. LIGHTING GLOSSARY TERMS
Downlights Light fixtures that direct all of the light in a downward direction. Most often are completely recessed into the ceiling, circular, or square-shaped, and less than 12" in diameter . Efficacy The amount of light produced per watt of electricity (lumens/watt). It is the rate at which a light source is able to convert electrical power (watts) into light (lumens), expressed in terms of lumens per watt (LPW). For example, a 10-watt lamp producing 800 lumens has an efficacy of 80 lumens per watt. ENERGY STAR A U.S. Environmental Protection Agency (EPA) voluntary program that helps businesses and individuals save money and protect our climate through superior energy efficiency. Flood Floodlights create a widespread distribution of light for illuminating a wall, sign, or large object or building. A floodlight should be well shielded with an accessory louver or shield to avoid stray light and glare. Fluorescent Lamps Lamps that operate by creating an electric arc inside a gas-filled tube. The color of the light is determined by the type of phosphor coating used in the lamp. Fluorescent Troffers Recessed fluorescent fixtures for 2-foot and 4-foot lamps, generally in modular sizes (2'X4', 1'X4', 2'X2'); commonly used in commercial spaces. Footcandle The unit of measure for the density of light as it reaches a surface. One footcandle is equal to one lumen per square foot. General Lighting Also known as ambient lighting, general lighting provides an area with overall, non-specific illumination. Glare Lighting that causes discomfort and impairs good visibility. High Bay Interior lighting where the roof trusses or ceiling height is greater than approximately 25 feet above the floor. Common in big box retail, warehouse, and industrial settings. High-Intensity Discharge (HID) An electric lamp that produces light directly from an arc discharge under high pressure. Metal halide, high-pressure sodium, and mercury vapor are types of HID lamps.
High-Pressure Sodium (HPS) Lamp type that uses sodium under high pressure as the primary light-producing element. HPS lamps produce a yellow light with a CCT of approximately 2,000K. HPS lamps are among the most efficacious light sources, with efficacies as high as 150 lumens per watt, although those with higher CRI values have efficacies as low as 25 lumens per watt. High Voltage Voltage that exceeds 50 volts. Incandescent Lamp Produces light with a wire filament, which creates light as it is heated by electric current. Kelvin Color temperature is measured in Kelvin, which indicates the hue of a specific type of light source. Higher temperatures indicate whiter, “cooler” colors, while lower temperatures indicate yellower, “warmer” colors (see CCT). Kilowatt (kW) 1,000 watts. Kilowatt-hour (kWh) A unit of measurement for electrical energy usage. One kilowatt-hour equals 1,000 watts of energy used for one hour. Job Site The physical location and address where the measures were installed. Lamp The light source within a fixture. Some types are referred to as a bulb or tube. Lens A glass or plastic diffuser used in luminaires to seal a fixture or control the exiting light. Light-Emitting Diode (LED) A semiconductor diode (electronic components that let electricity pass in only one direction) that emits visible light when electricity is applied and is used in lamps and digital displays. LED is available in a wide variety of colors and lighting fixture types and typically has a much longer-rated life than traditional lighting technologies. Lighting Power Density (LPD) A measure of the total lighting power in watts used per square foot of a building's area. It is calculated by dividing the total wattage of all lighting fixtures in a space by the total square footage of that space. Line Voltage The voltage supplied by a power line, measured at the point of use.
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