Definitions relating to outdoor lighting within Lower Merion Township shall be as set forth below. Any items related to outdoor lighting that are not included below shall be defined as per ANSI/IES Lighting Science: Nomenclature and Definitions for Illuminating Engineering, LS-1-20 (or most current version).
ABSOLUTE PHOTOMETRYMeasurement of the actual photometric quantities produced by a lighting product under test. Reference Standard IES LM-79.
ACCENT LIGHTINGDirectional lighting to emphasize a particular object or surface feature, or to draw attention to a part of the field of view.
AERIAL SPORTSSports which involve playing with an object (such as a ball) is in the air at least part of the time.
ARCHITECTURAL LIGHTINGLighting designed to reveal architectural beauty, shape and/or form and for which lighting for any other purpose is incidental.
ASTRONOMIC TIME SWITCHAn automatic lighting control device that switches outdoor lighting relative to time of solar day with time of year correction.
AUTHORITYThe adopting municipality, agency or other governing body.
BACKLIGHTFor an exterior luminaire, lumens emitted in the quarter sphere below horizontal and in the opposite direction of the intended orientation of the luminaire. For luminaires with symmetric distribution, backlight will be the same as forward light.
BUGA luminaire classification system that classifies backlight (B), uplight (U) and glare (G).
CANOPYA covered, unconditioned (may be open to the elements with no heating or air conditioning) structure with at least one side open for pedestrian and/or vehicular access.
CLASS OF PLAY (FOR RECREATIONAL LIGHTING)A. Class I - Facilities with spectator capacity over 5,000.
II II - Facilities with spectator capacity up to 5,000.
IIIIII - Facilities with spectator capacity up to 2,000.
IV IV - Facilities with limited or no provision for spectators.
Table 11.1 Class of Play |
|---|
Faculty | Class |
|---|
| I | II | III | IV |
|---|
Professional | • | | | |
College | • | • | | |
Semi-professional | • | • | | |
Sports club | • | • | • | |
Amateur leagues | • | • | • | |
High school | • | • | • | |
Training facilities | | | • | • |
Elementary school | | | | • |
Recreational event | | | | • |
Social event | | | • | |
COMMON OUTDOOR AREAOne or more of the following: a parking lot; a parking structure or covered vehicular entrance; a common entrance or public space shared by all occupants of the domiciles.
CURFEWA time defined by the authority when outdoor lighting is reduced or extinguished:
A. Curfew times shall not apply to low impact security lighting controlled by a motion sensor. Low impact lighting shall have a color temperature no greater than 3000K, shall not exceed 1, 260 luminaire lumens, and shall be aimed or shielded to minimize light trespass on adjacent properties.
DIRECT GLAREGlare resulting from high luminances or insufficiently shielded light sources in the field of view. A direct glare source may also affect performance by distracting attention.
DISABILITY GLAREThe effect of stray light in the eye whereby the contrast of the retinal image is reduced and, consequently, whereby visibility and visual performance may also be reduced. A direct glare source that produces discomfort may also produce disability glare by introducing a measurable amount of stray light in the eye.
DISCOMFORT GLAREGlare that produces visual discomfort. It does not necessarily interfere with visual performance or visibility.
EMERGENCY LIGHTINGLighting provided in the event on an emergency situation where a loss of power results in the failure of normal illumination or otherwise required by Code.
EYE LEVELFor purposes of calculation of illumination levels, a height of 4 1/2 feet.
FOOTCANDLEThe unit of measure expressing the quantity of light received on a surface. One footcandle is the illuminance produced by a candle on a surface one foot square from a distance of one foot.
FORWARD LIGHTFor an exterior luminaire, lumens emitted in the quarter sphere below horizontal and in the direction of the intended orientation of the luminaire.
FULLY SHIELDED LUMINAIREA luminaire constructed and installed in such a manner that all light emitted by the luminaire, either directly from the lamp or diffusing element, or indirectly by reflection or refraction from any part of the luminaire, is projected below the horizontal plane through the luminaire's lowest light-emitting part.
GLARELight entering the eye directly from luminaires or indirectly from reflective surfaces that causes visual discomfort or reduced visibility.
HARDSCAPEPermanent hardscape improvements to the site including parking lots, drives, entrances, curbs, ramps, stairs, steps, medians, walkways and non-vegetated landscaping that is ten feet or less in width. Materials may include, but are not limited to concrete, asphalt, stone and gravel.
HARDSCAPE AREAThe area measured in square feet (SF) of all hardscape. It is used to calculate the Total Site Lumen Limit in both the Prescriptive Method and Performance Methods. Refer to "Hardscape" definition.
HARDSCAPE PERIMETERThe perimeter measured in linear feet is used to calculate the Total Site Lumen Limit. Refer to "Hardscape" definition.
IDAInternational Dark Sky Association.
IESIlluminating Engineering Society.
IMPERVIOUS MATERIALAny material which prevents or impedes the natural absorption of stormwater directly into the ground.
LAMPA generic term for a source of optical radiation (i.e. "light"), often called a "bulb" or "tube." Examples include incandescent, fluorescent, high-intensity discharge (HID) lamps, and low-pressure sodium (LPS) lamps, as well as light-emitting diode (LED) modules and arrays.
LANDSCAPE LIGHTINGLighting of trees, shrubs, or other plant material as well as ponds and other landscape features.
LIGHT LOSS FACTOR (LLF)The ratio of illuminance (or exitance or luminance) for a given area to the value that would occur if lamps operated at their (initial) rated lumens and if no system variation or depreciation had occurred.
LIGHT POLLUTIONAny adverse effect of artificial light including, but not limited to, glare, light trespass, sky glow, energy waste, compromised safety and security, and impacts on the nocturnal environment.
LIGHT TRESPASSLight that falls beyond the property it is intended to illuminate.
LIGHTING"Electric" or "man-made" or "artificial" lighting. See "lighting equipment."
LIGHTING EQUIPMENTEquipment specifically intended to provide artificial illumination, including, but not limited to, lamp(s), luminaire(s), ballast(s), driver(s), poles, posts, lens(s), and related structures, electrical wiring, and other necessary or auxiliary components.
LOW VOLTAGE LANDSCAPE LIGHTINGLandscape lighting powered at less than 15 volts and limited to luminaires having a rated initial luminaire lumen output of 525 lumens or less.
LUMENThe unit of measure used to quantify the amount of light produced by a lamp or emitted from a luminaire (as distinct from "watt," a measure of power consumption).
LUMINAIREThe complete lighting unit (fixture), consisting of a lamp, or lamps and ballast(s), driver(s) (when applicable), together with the parts designed to distribute the light (reflector, lens, diffuser), to position and protect the lamps, and to connect the lamps to the power supply.
LUMINAIRE LUMENSFor luminaires with relative photometry per IES, it is calculated as the sum of the initial lamp lumens for all lamps within an individual luminaire, multiplied by the luminaire efficiency. If the efficiency is not known for a residential luminaire, assume 70%. For luminaires with absolute photometry per IES LM-79, it is the total luminaire lumens. The lumen rating of a luminaire assumes the lamp or luminaire is new and has not depreciated in light output.
NEW LIGHTINGLighting for areas not previously illuminated; newly installed lighting of any type except for replacement lighting or lighting repairs.
OBJECTA permanent structure located on a site. Objects may include statues or artwork, garages or canopies, outbuildings, etc.
OBJECT HEIGHTThe highest point of an entity, but shall not include antennas or similar structures.
ORNAMENTAL LIGHTINGLighting that does not impact the function and safety of an area but is purely decorative, or used to illuminate architecture and/or landscaping, and installed for aesthetic effect.
ORNAMENTAL STREET LIGHTINGA luminaire intended for illuminating streets that serves a decorative function in addition to providing optics that effectively deliver street lighting. It has a historical period appearance or decorative appearance.
OUTDOOR LIGHTINGLighting equipment installed within the property line and outside the building envelope, whether attached to poles, building structures, the earth, or any other location; and any associated lighting control equipment.
PARTLY SHIELDED LUMINAIREA luminaire with opaque top and translucent or perforated sides, designed to emit most light downward.
PEDESTRIAN HARDSCAPEStone, brick, concrete, asphalt or other similar finished surfaces intended primarily for walking, such as sidewalks and pathways.
PHOTOELECTRIC SWITCHA control device employing a photocell or photodiode to detect daylight and automatically switch lights off when sufficient daylight is detected.
POINT METHODA procedure for predetermining the illuminance at various locations in lighting installations by use of luminaire photometric data. The direct component of illuminance due to the luminaires and the inter-reflected component of illuminance due to the room surfaces are calculated separately. The sum is the total illuminance at a point.
PRIMARY LINE-OF-SIGHTThe line connecting the point of observation and the point of fixation. In terms of a single eye, it is the line connecting the point of fixation and the center of the entrance pupil.
PROPERTY LINEThe edges of the legally defined extent of privately owned property.
RECREATIONAL ESTABLISHMENTSAssembly or accessory uses intended for participation in or viewing outdoor activities that involve 100 or more participants and/or spectators.
REPLACEMENT LIGHTINGLighting installed specifically to replace existing lighting in the same location.
SALES AREAUncovered area used for sales of retail goods and materials, including but not limited to automobiles, boats, tractors and other farm equipment, building supplies, and gardening and nursery products.
SEASONAL LIGHTINGTemporary lighting installed and operated in connection with holidays or traditions.
SEQUENCE OF OPERATIONA document, added to the end of the drawing set, specifying the functionality of the lighting control system.
SHIELDED DIRECTIONAL LUMINAIREA luminaire that includes an adjustable mounting device allowing aiming in any direction and contains a shield, louver, or baffle to reduce direct view of the light source.
SIGNAny writing, symbol, figure, representation, logo, emblem, flag, banner, device, letter, word, street clock or temperature announcement which shall include any announcement, declaration, demonstration, display, illustration, name identification, description or insignia, which is used to advertise or promote the interest of any person or firm when such representation is placed in view of the general public.
SKY GLOWThe brightening of the nighttime sky that results from scattering and reflection of artificial light by moisture and dust particles in the atmosphere. Sky glow is caused by light directed or reflected upwards or sideways and reduces one's ability to view the night sky.
TEMPORARY LIGHTINGLighting installed and operated for periods not to exceed 60 days, completely removed and not operated again for at least 30 days.
THIRD PARTYA party contracted to provide lighting, such as a utility company.
TIME SWITCHAn automatic lighting control device that switches lights according to time of day.
TRANSLUCENTAllowing light to pass through, diffusing it so that objects beyond cannot be seen clearly (not transparent or clear).
UPLIGHTFor an exterior luminaire, flux radiated in the hemisphere at or above the horizontal plane.
VERTICAL ILLUMINANCEIlluminance measured or calculated in a plane perpendicular to the site boundary or property line.
Figure 11.1 Shielded and Unshielded Fixture Types |
