Several sections in the code call for "cutoff" fixtures as defined by the IESNA. Perhaps you're aware that the IES recently released its recommendation RP-33-99, Lighting for the Exterior Environments. In that document the IES provides revised definitions for fixture design. The term "cutoff" is defined on page 17 as "A luminaire light distribution where the candela per 1000 lamp lumens does not numerically exceed 25 (2.5 percent) at an angle of 90 degrees above nadir, and 100 (10 percent) at a vertical angle of 80 degrees above nadir."

The term "full cutoff" is defined as "A luminaire light distribution where zero candela intensity occurs at an angle of 90 degrees above nadir, and at all greater angles from nadir." From 80 to 90 degrees above nadir the definition is the same as for cutoffs.

Compared to a cutoff, a full cutoff design usually distributes less light at angles between 80 to 90 degrees above nadir as well as a few degrees below 80 degrees. Consequently, full cutoffs are usually less glaring to drivers, yet they distribute full intensity light distribution to the ground at a distant up to roughly four times the fixtures' mounting height. Such a distance is optimum, as illumination beyond that point is generally insufficient regardless of fixture design. (See IDA Information Sheet 78 at the IDA site www.darksky.org.)

Recommendation: Substitute the term "full cutoff" for the term "cutoff" in the code draft.

The essential components of a comprehensive lighting code are the full cutoff requirement, limits on illumination levels, and limits on "light trespass." This code contains some illumination limits and a cutoff provision, but establishes no standard for excessive light spillage on other property. Indianapolis has a few vague outdoor lighting ordinances. One merely states commercial lighting shall not create "excessive direct glare" onto adjacent property. The city plan department and legal department believe this provision to be subjective and make no attempt to enforce it, rendering the ordinance useless.

Recommendation: Establish standards for light trespass according to land use zoning. For non-commercial parcels we recommend a level of .1 fc (one-tenth footcandle) of horizontal or vertical illumination measured at the property line. For commercial/industrial parcels adjoined by other commercial/industrial parcels we suggest .2 fc (two-tenths), horizontal or vertical illumination. Usage such as drive-in theaters would need a more restrictive standard.

This chapter and several others exclude period piece fixtures from the "cutoff" requirement. Such fixtures are widely available with cutoff (and full cutoff) characteristics. The original design of many period fixtures is that of an exposed light source mounted on top of a post. Such a design yields poor visibility for two reasons. The post blocks illumination, creating a dark area below the fixture and creating poor uniformity of illumination, making pedestrians less visible. Consequently, such fixtures are often spaced very close together so that one fixture illuminates the dark post area of another. Additionally, a light source in the field of view creates what illuminating engineers and optometrists call "veiling luminance." (See IDA reference information accessible through the IDA web site search engine.) We visually experience a veil over our field of view which reduces the contrast needed to distinguish objects. Light fixtures from an era gone by didn't have today's high intensity discharge bulbs, but rather much less intense gas flames or incandescent bulbs. In pursuit of true historical accuracy, such fixtures should not contain HID bulbs. Installing HID bulbs into period fixtures often works poorly just as does putting Indy 500 car engines into model T's.

Because glare from some period fixtures is minimally diffused and in full view, low pole height means such glare is in a central position within the field of view for drivers and pedestrians. This glare means some period fixtures will also fail the standard in chapter 4, section 1, to "preclude glare onto or direct illumination of adjacent properties and streets."

Period fixture glare can be reduced through full cutoff design, reduced allowable bulb intensity, and higher fixture height (with a corresponding increase in glare projected into adjacent properties.) Some of these options could also render minimum illumination levels unreachable with a given lumen limit.

Recommendations: Maintain a full cutoff requirement for all fixtures. Otherwise, reduce the allowed 10,500 lumen bulb intensity to 5,000 or less as a maximum. (In many codes 1800 lumens is the maximum allowed for non-full cutoffs.) Set minimum pole height at least at 16 ft., and higher if 10,500 lumens in non-full cutoff fixtures is allowed. For applicants intent on historical authenticity, original gas flame or incandescent light sources should be used.

The illumination limits are excellent and offer some compensation for the possible lack of shielding requirements. In Section 2 (c) the provision is not clear as to whether shielding is required other than that provided by the canopy edge. The following assumes no absolute requirement that fixtures be recessed into the ceiling or be fully shielded: For most ceiling fixture locations, the typical width of a canopy's edge cannot provide shielding of a ceiling-mounted fixture from a viewing angle below a few degrees below a horizontal line through the bottom of the canopy edge. A fixture located only ten feet from the canopy edge would require an edge extending five feet below a horizontal line through the bottom of the fixture to achieve a 67 1/2 degree glare cutoff angle. In other words, the fixtures will not be shielded from glare from adjacent roadways or properties by the canopy edge.

The following is a draft for the IDA Outdoor Lighting Code Handbook:

Lighting under canopies, pavilions, or drive-through bays is subject to the following;

Also excellent. It is not clear why pole location is stipulated. "Forward throw" fixtures are available which provide excellent cutoff behind the fixture. Also see above general comments Re: light trespass standards.

Section 2 (b) "…lighting fixtures shall be specified, mounted, and aimed …so that no direct illumination is directed off the site." Technically this is impossible to comply with unless there is a definition for "direct illumination" which makes it operable. Otherwise, direct illumination is the illumination the occurs from a direct line a sight to a light source. Unless shielding extends to extreme distances from the bulb, light is emitted from its edges so it is part of the light source. Consequently, the provision is somewhat subjective and possibly not enforceable.

Recommendation: A light trespass standard would define the acceptable amount of light spillage. Also, defining direct illumination as "light distribution from within a light fixture's angular beam spread as indicated by the manufacturer or certified by a qualified engineer" allows for determining proper fixture aim.

Despite the special needs of sports lighting it does not require unlimited amounts of illumination.

Recommendation: Set illumination limits of 30 fc horizontal maintained average illumination of the playing field.

The bright, late night illumination of outdoor facilities deprives others of the enjoyment of the night sky.

Recommendation: Set curfews after which specified events may not commence, such as 10 p.m. for a softball game.

Considering that separate security lighting systems are discouraged in Section 1, it is not clear how the illumination level maximums stipulated in the table can be met for businesses more brightly illuminated when open.

In Section 2 (b) the provision limiting the height above which facades cannot be illuminated is interesting. An alternative regarding lighting of building facades is to allow after hours illumination of building entryways only.

We urge including a provision that facade illumination be achieved by downward directed soffit lighting, or lighting precisely aimed so that no light is directed into the sky. Illumination of pitched roofs usually cannot be achieved without directing light upward which creates urban sky glow, or directing lighting at angles that creates glare. Roof lighting usually serves only the purpose of advertising except for unique structures of special architectural character.

These chapters provide good provisions for sign lighting. Re: Chapter 11, Section 2 (d) "To the extent practicable, fixtures used to illuminate signs shall be top mounted and directed downward." It is not clear what the phrase "to the extent practicable" means.

Require that the lights of businesses be turned off each night after the business has closed and been vacated, except low level lighting illuminating building entryways to provide security.

Prohibit the use of search lights for advertising.

Set minimum distances from residential parcels for sports tower lighting. Require unanimous approval by adjoining property owners prior to sports lighting installation.