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Light Trespass

Potential sources include street lighting, security lighting, sports, lighting, billboards and signs, and car headlights.

Such unwanted light can potentially by an annoyance, a serious nuisance or even a serious health and safety risk if it adversely affects visibility for other tasks.

Environmental Zones
Zone Description
Zone E1 Areas with intrinsically dark landscapes. Examples are national parks, areas of outstanding natural beauty, or residential areas where inhabitants have expressed a strong desire that all light trespass be strictly limited. (This is the most sensitive zone.)
Zone E2 Areas of low ambient brightness. These may be outer urban and rural residential areas. Roadwas may be lighted to typical residential standards.
Zone E3 Areas of medium ambient brightness. These will generally be urban residential areas. Roadways will normally be lighted to typical traffic route standards.
Zone E4 Areas of high ambient brightness. Normally these are urban areas having both residential and commercial use and experiencing high levels of night time activity.
Luminaire Classification
Type I Closest setback from roadway (or mounted over roadway)
Type II Greater setback than Type I, less than Type III
Type III Greater setback than Type II, less than Type IV
Type IV Greatest setback from roadway
Type V Axially symmetric; produces a circular illuminance pattern
Cutoff Classifications
Full Cutoff: A luminaire light distribution where zero candela intensity occurs at an angle of 90° above nadir, and at all greater angles from nadir.
Cutoff: A luminaire light distribution where the candela per 1000 lamp lumens does not numerically exceed 25 (2.5 percent) at an angle of 90° above nadir, and 100 (10 percent) at a vertical angle of 80° above nadir. These applies to all lateral angles around the luminaire.
Semicutoff: A luminaire light distribution where the candela per 1000 lamp lumens does not numerically exceed 50 (5 percent) at an angle of 90° above nadir, and 200 (20 percent) at a vertical angle of 80° above nadir. This applies to all lateral angles around the luminaire.
Noncutoff: A luminaire light distribution where there is no candela limitation in the zone above maximum candela.
Walkways
Walkways Distant from Roadways and Type B Bikeways Minimum Average Horizontal Illuminance Levels on Pavement* (footcandles) Average Vertical Illuminance Levels for Special Pedestrian Security (footcandles)
Walkways and Bikeways 0,5 0,5
Pedestrain Stairways 0,5 1
Pedestrain Tunnels 2 5,5
*Uniformity ratios should not be greater than 10:1 maximum to minimum
Parking Lots
  Basic 1 Enhanced Security² IESNA Security Lighting Committee
Minimum Horizontal Illuminance³ 0.2 fc 0.5 fc 0.5 fc
Uniformity Ratio Maximum to Minimum6 20:01 15:01 15:01
Minimum Vertical Illuminance7 0.1 fc 0.25 fc 0.5 fc
Building Entries
A Pulic Spaces 30 lux 3 fc
B Simple orientation for short visits 50 lux 5 fc
Facade
Area Description Average Target Illuminance (vertical) (lux/footcandles) From IESNA Lighting Handbook 9th Edition
Bright Surroundings and Light Surfaces 50/5 50/5
Bright Surroundings and Dark Surfaces 100/10 150/15
Dark Surroundings and Light Surfaces 20/2 20/2
Dark Surroundings and Dark Surfaces 50/5 50/5

LOGO_-_ALA_-_20151013Architectural Lighting Alliance

Dallas | Lubbock | Shreveport

Dallas Phone: 214.658.9000
Dallas Fax: 214.658.9002

Dallas Phone: 214.658.9000
Dallas Fax: 214.658.9002

Lubbock: 806-796-1322
Lubbock Fax: 806-796-1323

Shreveport: 318-674-2713
Shrev. Fax: 318-674-2741

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