Advanced Lighting Guidelines Glossary
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ALL A B C D E F G H I J K L M N O P Q R S T U V W X Y Z 0-9
Saturation A characteristic of the response to a stimulus in which increasingly large changes in the stimulus produce decreasingly small changes… More »
Scalar illuminance The average illuminance on the surface of an infinitesimally small sphere at a point – also called mean spherical illuminance.… More »
Scattering The change in direction of a light ray caused by an interaction with localized non-uniformities in a medium. Original Chapter… More »
Scene A dimming level that is intended to be repeatable with a push of a button. Original Chapter Source: Controls Provided… More »
Scheduling An energy-saving lighting control strategy for switching or dimming during hours when a building space is unoccupied or occupied by… More »
Scotopic (scotopic vision) The state of vision in which only rod photoreceptors are active. Conventionally, scotopic vision is taken to occur at adaptation… More »
Scotopic/Photopic Ratio The ratio of scotopic luminous flux to photopic luminous flux produced at a point by a light source or a… More »
Sequence of Operations Description of how a lighting control system responds to various inputs in a given space. Example: “The occupancy sensor will… More »
Series When lamps are wired to a ballast in series, if any of the connected lamps fail, all the lamps are… More »
Shading masks Parts of the sky dome that are blocked by exterior surfaces, such as the landscape, neighboring buildings and building-mounted shading… More »
Simple payback Method of economic evaluation expressed in units of time (the payback period) to recoup an investment based on the initial… More »
Size of detail For a visual stimulus, the size of detail is always expressed in terms of the angle subtended by the detail… More »
Skyglow The glowing atmosphere above populated areas that interferes with view of the night sky. Original Chapter Source: Luminaires Provided By:… More »
Skylights Apertures in the roof of a building that allow daylight into the interior. They are usually covered by a transparent… More »
Snapback The reversion of luminaires with CFLs back to incandescent light sources. Original Chapter Source: Sources Provided by: Erik Page More »
Solar Heat Gain Coefficient (SHGC) The Solar Heat Gain Coefficient (SHGC) measures how well a window blocks heat from sunlight. The SHGC is the fraction… More »
Solar radiation Electro-magnetic radiation emitted by the sun. This comprises infrared, visible, and ultraviolet light. Original Chapter Source: Daylighting Provided by: Kosta… More »
Solar spectrum The amount of radiation emitted in each wavelength that composes solar radiation. Original Chapter Source: Daylighting Provided by: Kosta Papamichael… More »
Solid angle The solid angle subtended by an object at a point is given by the area of the object divided by… More »
Solid state lighting (SSL) A form of lighting that uses semi-conductor materials to emit light, rather than using glowing filaments or gas-discharge sources.  Original… More »
Source efficacy The ratio of light output of a light source to input power. Original Chapter Source: Sources Provided by: Erik Page More »
Spacing Criteria (SC) A multiplying factor calculated for a specific luminaire, which describes how far apart the luminaires can be spaced to deliver… More »
Spectral sensitivity The sensitivity of the effect of interest to wavelength. The effect of interest can be visual, e.g., brightness, or non-visual,… More »
Specular Mirror-like reflective properties where the angle of incidence equals the angle of reflectance. Original Chapter Source: Design Considerations Provided By:… More »
Specular reflection A mirror-like reflection in which the angle of incidence is equal to the angle of reflection. Original Chapter Source: Health… More »
Spot relamping A method of replacing lamps only after they have failed. Original Chapter Source: Sources Provided by: Erik Page More »
Standard 189.1 ASHRAE Standard 189.1, a reach code designed to improve on the efficiency of Standard 90.1, similar to the LEED system,… More »
Standard 90.1 ANSI/ASHRAE/IES Standard 90.1, the federally referenced energy code, originally developed by ASHRAE, and now revised and updated in collaboration with… More »
Step-dimming ballast A ballast that reduces light levels by one or more steps between full light output and OFF. Original Chapter Source:… More »
Steradian SI unit of solid angle. Original Chapter Source: Design Considerations Provided By: Leslie North More »
Sunlight need definition More »
Suprachiasmatic nuclei (SCN) The master clock of the human circadian system. Original Chapter Source: Health & Performance Provided By: Peter Boyce More »
Switch A control device that provides ON/OFF lighting control by mechanically closing or opening the circuit.  Original Chapter Source: Controls Provided… More »
System efficacy Also referred to as relative system efficacy, system efficacy is a measurement of a system's ability to convert electricity into… More »
Systems Manual Document produced over the course of a project and delivered to the owner upon acceptance, which provides detailed information about… More »
ALL A B C D E F G H I J K L M N O P Q R S T U V W X Y Z 0-9

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