Advanced Lighting Guidelines Glossary
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Definition
DALI (Digital Addressable Lighting Interface) A marketing term developed by DALI-AG often used generically to describe a royalty-free, non-proprietary, two-way, open and interoperable digital protocol… More »
Daylight Light originating directly from the sun or direct sunlight that is scattered by the atmosphere. Original Chapter Source: Daylighting Provided… More »
Daylight harvesting The appropriate turning off of electric lighting systems during times at which sufficient daylight is available for visual tasks that… More »
Daylight zone Area of consistent and substantial daylight availability within a building, expressed in square feet. Also called the daylight area. Original… More »
Daylighting Lighting strategies that use the sky as a light source, while shielding or reflecting direct sunlight to avoid glare, heat… More »
Daylighting control Control strategy in which lighting is either switched OFF or dimmed when photosensor-measured incoming or task light levels rise above… More »
Demand charge Utility rate structure which charges based upon peak electric demand use during the billing month. Fee rate is in $/kW.… More »
Demand response Allows customers to bid into the power supply system by reducing building consumption during pre-defined peak load conditions. Original Chapter… More »
Design parameters Parameters that designers control to affect performance. Original Chapter Source: Daylighting Provided By: Kosta Papamichael / CLTC More »
Device Settings Document listing all adjustable lighting controls in a project, identifying them by individual space or space type, and then clearly… More »
Diabetic retinopathy A common cause of partial sight caused by chronic diabetes. The effect is to damage parts of the retina. The… More »
Dichroic coatings Optically-thin layers of metalic materials applied to the lens or glass envelopes of lamps to selectively reflect or transmit certain… More »
Dielectric Nonconducting substance. Original Chapter Source: Luminaires Provided By: Leslie North More »
Diffuse daylight Daylight not originating directly from the sun or from specular reflections of the sun. Original Chapter Source: Daylighting Provided By:… More »
Diffuse reflectance The ratio of the luminous flux reflected from a surface to the luminous flux incident on the surface. Original Chapter… More »
Dim The act of reducing light intensity. Original Chapter Source: Daylighting Provided By: Kosta Papamichael / CLTC More »
Dimmable ballast Fluorescent or HID ballast specially designed to provide the ability to adjust light output by modifying the lamp current. Original… More »
Dimmer A control device for varying the light output of lamps. Original Chapter Source: Controls Provided By: Craig DiLouie More »
Direct Glare Glare caused by a light source directly visible. Original Chapter Source: Design Considerations Provided By: Leslie North More »
Disability glare Glare that causes a deterioration in visual capabilities. Disability glare is caused by light being scattered in the eye, the… More »
Discharge lamps Electric light sources which produce light by passing electrical current through an ionized gas.  Examples include neon lamps, xenon flash… More »
Discomfort glare Glare that causes discomfort. Discomfort glare does not necessarily cause a deterioration in visual capabilities. Original Chapter Source: Health &… More »
Distributed control Control strategy involving distribution of smaller control panels throughout a facility close to the loads they control. Original Chapter Source:… More »
Distributed intelligence Control system in which microprocessor intelligence and functionality is embedded in the control devices attached to the lighting network rather… More »
DMX512 A digital communications protocol most commonly used to control theatrical, stage and entertainment lighting and effects. Original Chapter Source: Controls… More »
Downlight A recessed luminaire usually using a point source, with a round or square aperture that projects light downward. Original Chapter… More »
Driver For light emitting diodes, a device that regulates the voltage and current powering the source. Original Chapter Source: Sources Provided… More »
Dual-loop photosensor Relatively new daylight harvesting technology combining open- and closed-loop photodiodes looking in different directions, with the result being greater accuracy… More »
Dual-switching A bilevel switching strategy involving dual-circuiting the inboard lamps separately from the outboard lamps in three-lamp luminaires, enabling three different… More »
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