NIGHT SKY AND DARK ENVIRONMENTS: BEST MANAGEMENT PRACTICES FOR ARTIFICIAL LIGHT AT NIGHT ON BLM-MANAGED LANDS TECHNICAL NOTE 457 44 Table 2. Maximum allowable BUG (backlight, uplight, and glare) ratings for lighting zones (LZs) 0 to 2. Source: IDA-IES Model Lighting Ordinance (IDA-IES 2011). MLO Lighting Zone LZ0 LZ1 LZ2 Backlight Rating > 2 mounting heights from edge of desired illumination area B1 B3 B4 1 to 2 mounting heights from edge of desired illumination area and ideally oriented B1 B2 B3 0.5 to 1 mounting heights from edge of desired illumination area and ideally oriented B0 B1 B2 < 0.5 mounting height to edge of desired illumination area and properly oriented B0 B0 B0 Uplight Rating U0 U1 U2 Allowed percent light emission above 90% for street or area lighting 0% 0% 0% Glare Rating Any luminaire not ideally oriented with 1 to < 2 mounting height to any edge of desired illumination area G0 G0 G1 Any luminaire not ideally oriented with 0.5 to 1 mounting height to any edge of illumination area G0 G0 G0 Any luminaire not ideally oriented with < 0.5 mounting height to any edge of illumination area G0 G0 G0 Example of Applying the BUG Rating System (see Table 2) In an area where LZ0 lighting standards are judged appropriate, the BUG rating for a luminaire under consideration might be rated: B0-U0-G1. A luminaire rated B0-U0-G1 would provide excellent control of backlight and uplight and good control of glare. However, because the glare rating of G1 is greater than G0, as indicated in Table 2, the luminaire does not meet the standard for LZ0 and so would not be suitable for use in areas where maintaining a very low level of light is important. 7 IES Recommended Practices publications include the following: RP-33-14, “Lighting for Exterior Environments”; RP-7-17, “Recommended Practice for Lighting Industrial Facilities”; RP-8-18, “Recommended Practice for Design and Maintenance of Roadway and Parking Facility Lighting”; and RP-39-19, “Recommended Practice: Off-Roadway Sign Luminance.” Relevant IES guides include: DG-22-12, “Sustainable Lighting: An Introduction to the Environmental Impacts of Lighting”; DG-29-11, “The Commissioning Process Applied to Lighting and Control Systems”; G-1-16, “Guide for Security Lighting for People, Property, and Critical Infrastructure”; LEM-3-13, “Upgrading Lighting Systems in Commercial and Institutional Spaces”; and LEM-7-13, “Lighting Controls for Energy Management.” The Luminaire Classification System, MLO, and Illuminating Engineering Society Recommended Practices7 provide guidance on selecting luminaires and appropriate lighting levels for specific applications. Choosing the appropriate LZ for an area allows enough lighting for tasks while minimizing the overall amount of light pollution generated.
RkJQdWJsaXNoZXIy NTkzMzk=