NIGHT SKY AND DARK ENVIRONMENTS: BEST MANAGEMENT PRACTICES FOR ARTIFICIAL LIGHT AT NIGHT ON BLM-MANAGED LANDS TECHNICAL NOTE 457 42 The LCS BUG rating system is based on a sphere around a hypothetical pole-mounted light source in the center of the sphere (Figure 4). The sphere is divided into three sections: backlight, uplight, and glare (or forward light). The three sections are further divided into zones in which the lumen distribution is rated to determine the light pollution effect of the luminaire. Figure 4 shows a schematic diagram of the BUG rating system, with the different colors representing the division of the light cast from the luminaire into backlight (yellow), uplight (blue), and glare (or forward light) (green) areas. The B, U, and G ratings represent how well the luminaire controls backlight (B), uplight (U), and glare (G), with 0 representing the best control and 5 indicating the worst control. BUG ratings should be used to describe luminaires rather than using the terms “fullcutoff,”“semi-cutoff,” and “no-cutoff.” The IDA-IES Model Lighting Ordinance (MLO) (IDA-IES 2011) is a publication designed to help municipalities develop outdoor lighting standards that reduce light pollution. The MLO identifies performance standards for selecting appropriate luminaires based on their BUG ratings. The MLO uses a system of lighting zones (LZs) to identify performance standards for areas with a desired level of lighting (Table 1). The MLO specifies the BUG rating for luminaires to meet the LZ performance standards (Table 2). Figure 4. Diagram of the backlight, uplight, and glare (BUG) rating system
RkJQdWJsaXNoZXIy NTkzMzk=