Evaluate the obtrusive light produced by our fictitious fast food environment BurgerWorld2. Consider the following:

  • Areas of concern: 50ft. perimeter around three sides of the site
  • Obtrusive Light Standard: AS 4282 (The Australian standard is excellent and can easily be used in other locations)
  • Application Conditions: Post-Curfew
  • Lighting Zone: Residential – Light Surrounds

Based on the selected Standard, Application Conditions and Lighting Zone, we have the following limits (these come from the Standard):

  • Maximum allowable vertical illuminance at areas of concern: 0.19fc (2 lx)
  • Maximum allowable luminous intensity from any one luminaire at areas of concern: 1000 cd

Using the Add-Calculation-Obtrusive Light-Vertical Planes command, we can quickly create vertical calculation grids around the site by specifying the grid reference line(s). Both Vertical Illuminance and Maximum Luminous Intensity grids can be created at the same time (Figure 1):

Figure 1

With four clicks (count ‘em, four), we created six grids of analysis around the site: Two grids of analysis (Vertical Illuminance and Maximum Luminous Intensity) for three sides of the site (Figure 2):

Figure 2

Once created and calculated, there are various tools available to help us determine if we have met the design criteria or not (obtrusive light limits). For example: Using Highlight Values, we can quickly identify where the Maximum Luminous Intensity exceeds our design level of 1000 Cd (Figures 3 & 4):

Figure 3

Figure 4

In order to determine the offending luminaire (luminaire contributing the most intensity at a particular point), we can use the Add-Calculation-Obtrusive Light-Toggle Cd/Lum# Display command (Ctrl+L) to toggle the display to show the luminaire number. In this case, the luminaire contributing the most intensity at the highlighted points is Luminaire #10 (not the closer Luminaire #7) (Figure 5):

Figure 5

When you are ready to evaluate the entire site for obtrusive light, use the Add-Calculation-Obtrusive Light-Compliance Test command. Select the desired Standard, Application Conditions, Lighting Zone and click Ok. Seconds later you’ll know if the environment passes or not! Need to evaluate for different conditions? Simply change the conditions and re-run the test. You can even make up your own test parameters (Custom Standard). It doesn’t get much easier (Figure 6)!

Figure 6