1、1 2 TM=lO=OO O Addressing Obtrusive Light (Urban Sky Glow and Light Trespass) in Conjunction with Roadway Lighting The LIGHTING AUTHORITY“ O Publication of this Committee Report has been approved by the IESNA. Suggestions for revisions should be directed to the IESNA. Prepared by The Obtrusive Light
2、 Subcommittee of the IESNA Roadway Lighting Committee Publication of this Committee Report has been approved by the IESNA. Suggestions for revisions should be directed to the IESNA. IESNA TM-10-00 IESNA Technical Memorandum Addressing Obtrusive Light (Urban Sky Glow and LightTrespass) In Conjunction
3、s with Roadway Lighting Prepared by: The Obtrusive Light Subcommittee of the IESNA Roadway Lighting Committee I Copyright 2000 by the Illuminating Engineering Society of North America. Approved by the IESNA Board of Directors, February 26,2000 as a Transaction of the Illuminating Engineering Society
4、 of North America. All rights reserved. No part of this publication may be reproduced in any form, in any electronic retrieval system or otherwise, without prior written permission of the IESNA. Published by the Illuminating Engineering Society of North America, 120 Wall Street, New York, New York 1
5、0005. IESNA Standards and Guides are developed through committee consensus and produced by the IESNA Office in New York. Careful attention is given to style and accuracy. If any errors are noted in this document, please for- ward them to Rita Harrold, Director Educational and Technical Development,
6、at the above address for verification and correction. The IESNA welcomes and urges feedback and comments. Printed in the United States of America. Prepared by the Obtrusive Light Subcommittee of the IESNA Roadway Lighting committee d II) Obtrusive Light Subcommittee William A. Hughes, Chair Bradford
7、, R.A. Canavan, M.G. Chapman, T.J. Cimino, V. Contos, P. Crawford, D.L. Daiber, W. Edmonds, J.W. Eslinger, G.A. Fairbanks, K. Kosiorek, A.S. Maltezos, M. McCormick, J. McGowan, T.K.* Mickel, J.J. Monahan, D.R. Monsoor, R.G. Morehead, W.E. Oerkvitz, C.A. Okon, D.W. Rowsell, E.C. a WGght, V.H. Roadway
8、 Lighting Committee John J. Mickel, Chair W. Adrian A.P. Allegretto* B. Ananthanaray- anan S.W. Annoh* J.B. Arens J.D. Armstrong J.A. Bastianpillai J. Bodanis* P.C. Box R.A. Bradford J.J. Buraczynski* K.A. Burkett J.C. Busser E. Cacique* M.G. Canavan V.F. Carney R.A. Catone* T.J. Chapman* B.T. Chau*
9、 D. Chaudhuri* A.Cheng* R.B. Chong V. Cimino R.D. Clear P. Contos C.W. Craig D.L. Crawford* M.D. Crossland C.L. Crouch* W. Daiber J.E. Degnan N. Dittman Z. Durys* G. Duve* W.H. Edman* G.A. Eclinger K. Fairbanks* T. Fenimore* D.H. Fox* M. Freedman* D.G. Garner* R. Gibbons* A.S. Goel* R.C. Gupta R.L.
10、Hamm G. Harlow* J.M. Hart G.A. Hauser* T.S. Hester* W.A. Hughes D.E. Husby* M.S. Janoff J.E. Jewell* R. Kauffman* M.E. Keck* D. Keith A. Ketvirtis A.S. Kosiorek J. Kroll* R. LeVere I. Lewin C.H. Loch P.J. Lutkevich D. Mace C. Miller* DA. Macha* M. Maltezos J. McCormick* S.W. McKnight J.F. Meyers D.R
11、. Monahan R.G. Monsoor W.E. Morehead* E. Morel H.D. Mosley* K. Negash* H. Odle C.A. Oerkvitz D.W. Okon J.L. Pimenta* G.P. Robinson* M.J. Robinson* A.S. Rose E.C. Rowsell P.P Sabau N.A. Schiewe R.N. Schwab B.L. Shelby* A.D. Silbiger* J. Simard R.L. Sitzema, Jr. G.E. Smallwood R.E. Stark R. Stemprok*
12、D.C. Strong* J.D. Turner* H.A. Van Dusen R. Vincent R.P. Vogel* V. H. Waight J.D. Walters C.P. Watson J. Weaver* S. Wegner* A. Williams* R.R. Wylie A.B. York* *Advisory Member *Honorary Member IESNA TM-1 0-00 Contents 1.OForeword ,.,.l 2.0Introduction . 3.0StrayLight 3.1 Sky Glow 3.2 LightTrespass 2
13、 3.3Glare . 4.0 Community Ordinances and Regulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2 5.0 Methods of Measuring and Evaluating Stray Light . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3 6.0 Solutions and M
14、itigation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3 6.1 Prevention - New Design. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3 6.2 Remedial Modification - Ex
15、isting Installations. . . . . . . . . . . . , . . . . . . . . . . . . . . . . . . . . . . . . 4 7.0Conclusion .4 References 5 For Further Reading 5 a Glossary .,.6 LI IESNA TM-10-00 IESNA Technical Memorandum Addressing Obtrusive Light (Urban Sky Glow and Light Trespass) in Conjunction with Roadway
16、Lighting 0 the beauty of the night environment. While the con- cerns and solutions for stray light problems can be described in several different ways, this technical memorandum will address three components: sky glow light trespass, and glare. 3.1 Sky Glow This Technical Memorandum addresses sky gl
17、ow, light trespass, and glare associated with roadway lighting. Roadway lighting has been estimated to account for approximately 30 percent of sky glow and light tres- pass. Designers should address these issues and pro- mote “good lighting” practices whenever possible. Misdirected or misapplied out
18、door lighting is a con- cern for aesthetic, environmental and energy man- agement reasons. This technical memorandum iden- tifies some of the issues and suggests lighting design solutions, which can be used as the basis for lighting ordinances or regulations. The impact of roadway lighting upon anim
19、al or plant life is outside the scope of this technical memoran- dum, but should not be ignored by designers and engineers responsible for outdoor lighting. 2.0 INTRODUCTION e For most of mans existence, there has been a desire to dispel the dark. During the past 100 years, applied technology has pr
20、ovided the ability to illuminate the outdoors so that most facilities can be used day and night. Millions of people can go shopping and travel the highways at night in comfort and safety. As the appli- cation of roadway lighting for convenience, security, and safety has increased, concern has arisen
21、 about adverse environmental effects. This has resulted in an increasing number of community regulations to control or limit all outdoor lighting, including roadway lighting. 3.0 STRAY LIGHT Recognition that stray light could cause problems was noted in the IESNA Lighting Handbook almost 25 years ag
22、o, but the recommendation to add glare shields or louvers to floodlights was limited to applica- tions adjacent to residential property. The adverse effects of roadway lighting were not considered. Most critics, while not opposed to roadway lighting, believe it can be provided in ways that help pres
23、erve 0 “Sky glow” is the term used to describe the added sky brightness caused by the scattering of electric light into the atmosphere, particularly from outdoor lighting in urban areas. This phenomenon is of concern to astronomers, and to a lesser extent, the general pub- lic. Sky brightness is att
24、ributed to the following factors: urbatdsuburban growth; lighting designs that disregard glare calculations and precautions; inappropriate light- ing equipment selection and installation. Sky bright- ness increases in proportion to the installed lumens, unless steps are taken to mitigate the problem
25、. Professional and amateur astronomers were among the first to sound the alarm about sky glow emanating from urban and surrounding areas. Professionals using com- mercial telescope sites, such as those at Mt. Palomar in California, Kitt Peak in Arizona, and Mauna Kea in Hawaii, and amateurs using mo
26、re conventional equip- ment in back yards, or in areas normally outside the influence of urban sky glow, have all reported increased visual impairment when viewing the heavens. While amateur astronomers do not have the large, sophisticated equipmen t employed by major observa- tories, they do use eq
27、uipment of high quality, and amateurs offen make discoveries that are passed on to professional researchers for further study. Despite the development of sophisticated telescopes, such as Hubble, there is an ongoing need to continue the use of established land-based telescope sites and the important
28、 role of amateur observers. Astronomers are particularly concerned about light directed above the horizontal plane or light reflected from surfaces, which becomes scattered in the atmosphere. The result is a luminous aura, or sky glow, over the cities of North America. As urban and suburban developm
29、ent increases, so does the desire for safe, secure and well-lighted resi- dential areas, and commercial zones with appealing and desirable attributes. Outdoor lighting and roadway illumination play a major role in creating these attrib- utes. Unfortunately, in some situations during the design proce
30、ss, consideration for the surrounding areas has been given low priority, resulting in increased sky glow.Thus, those nearby suburban res- idents, who are now experiencing the negative con- sequences, are looking for solutions. 1 IESNA TM-10-00 I In addition, citizens are becoming more energy-con- sc
31、ious and are speaking out about wasted energy when they see light incident upon surfaces outside the intended area, or directed into the sky, or shining into adjacent buildings. (See Section 3.2.) It is important that sky glow and uncontrolled light impinging on adja- cent properties be minimized th
32、rough appropriate light- ing designs or the design process itself could become constricted by hasty and uninformed rule making. 3.2 Light Trespass Light that strays from its intended purpose can become a visual annoyance, or even temporarily dis- abling. The term “light trespass” is used to describe
33、 this effect. The spread of sky glow (see Section 3.1) and light trespass are closely connected. Most com- plaints about light trespass come from people upset by stray light entering their windows or intruding upon their property. Those who would enjoy a sparkling panorama of distant lights object w
34、hen nearby street lights interfere with their view. Similar conditions occur when stray light from private property briefly impairs vision for automobile drivers. In most cases, the prob- lem is traceable to inappropriate lighting design. Lack of community involvement leads to misunderstanding or mi
35、sinterpretation of design criteria and priorities (e.g., cost, lead time, styling, safetyhecurity of pedes- trians and motorists). Inappropriate maintenance results in components of the system being replaced incorrectly or adjusted and aimed improperly. Light trespass has long been treated simply as
36、 a symptom of urban growth. Although a concern to lighting designers and citizens in years past, there is little documentation that defines light trespass criteria or offers solutions. Severe problems may have been addressed by shielding or relocating offending lumi- naires, or using different lumin
37、aire types. In an effort to solve light trespass problems, various communities are now adopting outdoor lighting ordi- nances or regulations. Some of these specify mea- surable limits for light trespass in terms of horizontal illuminance at or within property lines. However, hori- zontal illuminance
38、 limitations may not address the issue as well as vertical illuminance and/or light source luminance limits. While such regulations enable easy measurement by municipal officials, they do little to help those who are troubled by a “bright” luminaire that may be located blocks - even miles - away in
39、an othennrise dark field of view. 3.3 Glare A severe form of light trespass involves glare. Glare is often considered to restrict the vision of people per- forming driving tasks. For example, extraneous bright light sources in the field of view may seriously affect a drivers vision, Visual confusion
40、 created by such sources can affect the drivers ability to locate and rec- ognize traffic signals or other traffic control devices, and to discern oncoming headlights. This visual dis- ability is increased when there are imbalances between ambient light levels, extreme brightness con- trasts, and di
41、fferences in human eye sensitivity. Additional technical information concerning glare may be found in RP-8-00 American National Standard Practice for Roadway Lighting. 0 4.0 COMMUNITY ORDINANCES AND REGULATIONS Note: The IESNA does not prescribe how, when, or if to write a light trespass/sky glow or
42、dinance, nor does it recommend the format or ascribe technical details. Publications cited in the references and the “further reading” list of this technical memorandum are only examples of final products produced by governmental and private groups. There may never be fully satisfactory answers to a
43、ll sky glow or light trespass problems, but the public mede :O be yiveii meihuds fr addressing ils con- cerns. Outdoor lighting installations will continue to accompany a growing population that prefers its road- ways, walkways, and bicycle ways to be lighted. Unfortunately, much hardware will be in
44、stalled without consideration for obtrusive light concerns. Therefore, lighting designers/engineers will be required to recom- mend workable solutions. Otherwise local jurisdictions will “solve” these problems by enacting legislation. There are many light control ordinances in existence, and more wi
45、ll certainly be adopted. It seems desir- able, therefore, that these ordinances be based upon scientific principles and be of uniform content. At pre- sent, designers cannot be certain that their work is in compliance, nor can manufacturers be assured that their products can be applied in all locati
46、ons. Certainly more understanding of the situation is necessary. Three approaches are recommended: education, research, and local input. It is in these areas where governments, citizens, astronomers, lighting design- ers, engineers, manufacturers, and others might develop cooperative programs to bri
47、ng sky glow and light trespass under control. 2 IESNA TM-10-00 Agreement on the principles and definitions of light trespass and practical limitations would result in the ability to calculate, measure and enforce the recom- mendations. (I) 5.0 METHODS FOR MEASURING AND EVALUATING STRAY LIGHT As stat
48、ed in Section 3.1, sky glow results when light is projected upwards, then scattered by the atmos- phere - a common occurrence over urban areas. While most sky glow is readily observable physically, electronically, or photographically, calculations can also be performed to describe this phenomenon. T
49、wo such methods are presented in the Commission Internationale de lclairage (CIE) document No. 126 (prepared by CIES TC 5.21) Guidelines forhninimizing Sky Glow. Information on estimating sky glow levels is found in Section 6, The Sky Glow Formula,” and in Section 7, “Rules of Thumb to Estimate Sky Glow.” Document No.126 also contains other practical infor- mation concerning sky glow and its effects on astron- omy. A good definition of light trespass as obtrusive light is provided by the CIE and is used in a Light Trespass Research Report.3 The definition states that obtrus
