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Light tresposs; Light failing where it
<br />
<br />is not wanted or needed. Light trespass also
<br />is intrusive lighting. Spill light (also called
<br />stray light) is Ii§tit failing outside of the
<br />intended ,]rea. which can result in ti§hr tres-
<br />pass. Li§ht cumin§ into a yard or bedroom
<br />window at night from street[i§hts, the nearby
<br />car dealer or marl, or from a neJ§hbor's
<br />security light is light trespass. This type of
<br />light pollution also has glare and wastes both
<br />light and energy.
<br />
<br /> Visual clutter and confusion: Light
<br />"noise" in the field of view that is both ,:tis-
<br />trotting and annoying. Examples might
<br />include too many brightly [it signs or too many
<br />bright lights. For example, visual clutter and
<br />confusion wuuld make it difficult to see or
<br />differentiate between directional signs and
<br />
<br />traffic si§nals.
<br /> Artificiol sky glow: The artificial bright-
<br />enin§ of the nj§hr sky due mostly to ineffi-
<br />cient lighting fixtures that project Ii§tit
<br />upward. Artificial sky §low is wasted light.
<br />It bmjhtens the night sky often to such
<br />an extent that only the moon and a few of
<br />the briL~htest stars remain visible.
<br />
<br />THE REGULATION OF LIGHT
<br />
<br />An outdoor li~htin§ control ordinance restricts
<br />lighti%, types, when they can be used, and
<br />other rnatters alfectin§ the quality and value
<br />,]1: the lightim~, type. Today, hundreds of light-
<br />in§ ordinances exist around the country, and
<br />the ,Jemand lot tl~em from [he public and §ov-
<br />~rnmental ngencJes is ~rowin§, as evidenced
<br />by !DA'J nearly daily requests for advice or
<br />,_~xamples ut such ordinances. Similarly, ~he
<br />,American P!annin§ Association's Plannin§
<br />Advisolv Service has received more char] ~oo
<br />
<br />lighting-related inquiries over the past
<br />
<br />to years.
<br />
<br /> Except in matters affecting' the safety
<br />of a person or security of property, outdoor
<br />lighting levels should be kept to a minimum,
<br />Lights should be adequately shielded,
<br />without glare or light trespass, operated
<br />at the lowest acceptable levels, and shut
<br />off when not needed. Most modern lighting'
<br />ordinances share several ~rovisions to
<br />carry out these objectives, including desig-
<br />nated lighting zones, regulations for.the
<br />amount of light permitted, lighting fixture
<br />shielding, and lighting curfews.
<br />
<br /> Lighting Zones. Lighting zones are based
<br />on the highly varied lighting needs within a.
<br />city or.re§ion and are a key element in modern
<br />lighting ordinances. The zones--recommended
<br />by IDA and the International Commission
<br />on Illumination (CiE)--at[ow different amounts
<br />of light in areas with different nighttime char-
<br />acteristics. Lighting zones are defined on
<br />the basis of ambient lighting levels, population
<br />density, and other community considerations.
<br />A description of the lighting zones is provided
<br />in the model ordinance.
<br /> Permitted Light. Copious amounts of
<br />light are not always an appropriate antidote
<br />for safety and security concerns. Too much
<br />lighting and §lore compromise the eye's night-
<br />time adaptation level. Furthermore, brightness
<br />from businesses, entertainment complexes.
<br />signs, street lighting, and parking lots has
<br />gradually increased over time and the public
<br />has gradually come to accept these unneces-
<br />sary levels. Franldy, night lighting' is now more
<br />about aovertising than security or safety.
<br />
<br /> Shielding. Light output can be controlled
<br />by addin§ shielding fixtures that direct light
<br />
<br />where it is needed, enhancing performance
<br />through strategic light guidance. High-quality
<br />fixtures also are glare free.
<br /> Curfews. Lighting curfews dictate when
<br />light is needed, which is not everywhere and
<br />at all times. Curfews help to limit light poilu-
<br />lion and energy waste by requiring' busi-
<br />nesses, institutions, and properb/owners to
<br />turn off unnecessary lights at specified times.
<br />
<br />THE IDA blOOEL LIGHTING ORDINANCE
<br />The remainder of this issue of Zoning Practice
<br />contains a model outdoor lighting ordinance.
<br />The dangers associated with excessive Jig'hr-
<br />lng call for a progressive lighting ordinance
<br />much the same way that inefficient develop-
<br />ment patterns necessitate a land-use code
<br />that will promote and protect better develop-
<br />ment practices. P~anners and ordinance
<br />drafters should consider the recommenda-
<br />tions of national lighting organizations such
<br />as IDA, the Illuminating Engineering Society of
<br />North America (IESNA), and the International
<br />CPTED (Crime Prevention Through Environ-
<br />mental Design) AssoCiation when establishing
<br />lighting policy.
<br />
<br /> Recognizing that existing ordinances vary
<br />in complexity and effectiveness, the IDA
<br />model attempts to establish a uniform, pra(Jti-
<br />cai ordinanc~ for use in local and regional
<br />§overnments throughout the country.
<br />
<br /> A collection of outdoor lighting ordi-
<br />nances incorporating "dark skies" principles
<br />is available to Zoning Practi£e subscribers by
<br />contacting Michael Oavidson. Editor, Zoning
<br />Practice, American P~anning Association,
<br />t22 South Michigan Avenue, Suite t6oo,
<br />Chicago. !L 6o6o~, or send an e-mail to
<br />mdavidson(_~plan nine. or§.
<br />
<br />70NINGF~;~C¥:C.~ 07.0~
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