CLC Lighting Calculations & Software 3 — Questions and Answers
Question 1: When performing an average-to-minimum uniformity ratio calculation for a roadway, which IES standard provides guidance?
- IES TM-30
- IES RP-8 (Correct answer)
- IES LM-79
- IES TM-21
Correct answer: IES RP-8
IES RP-8 (Roadway Lighting) specifies uniformity criteria including average-to-minimum and maximum-to-minimum ratios for roadway applications.
Question 2: What does a 'luminous intensity distribution curve' (LIDC) plotted in polar form directly show?
- The spectral power distribution of the light source
- Candela output in all directions around the luminaire (Correct answer)
- The correlated color temperature across beam angles
- Illuminance values on the work plane below
Correct answer: Candela output in all directions around the luminaire
A polar LIDC plots candela values at every angle around the luminaire, visually showing the shape and intensity of the light distribution.
Question 3: In energy code compliance calculations (ASHRAE 90.1), LPD is expressed as:
- Lumens per watt (lm/W)
- Watts per square foot (W/ft²) (Correct answer)
- Footcandles per fixture
- Candela per square meter
Correct answer: Watts per square foot (W/ft²)
Lighting Power Density (LPD) is the total wattage of lighting divided by the floor area, expressed as W/ft² in US energy codes.
Question 4: Which software tool is specifically designed for outdoor sports lighting compliance with IESNA RP-6 standards?
- AGi32 with Sports Lighting module (Correct answer)
- AutoCAD MEP
- SketchUp Pro
- Revit Architecture
Correct answer: AGi32 with Sports Lighting module
AGi32 includes dedicated sports lighting calculation features that support IESNA RP-6 analysis for athletic facilities.
Question 5: A luminaire has a BUG rating of B2-U0-G1. What does the U0 component indicate?
- Zero uplight output, fully shielded above horizontal (Correct answer)
- Uniform distribution in all directions
- Upward glare rating of zero on a five-point scale
- Under-lit conditions with no upward component
Correct answer: Zero uplight output, fully shielded above horizontal
In the BUG (Backlight-Uplight-Glare) rating system, U0 means zero uplight — no light is emitted above 90°, making it fully cutoff for upward light.
Question 6: The Unified Glare Rating (UGR) formula includes which of the following variables?
- Luminaire wattage and room voltage
- Background luminance, solid angle, and luminous intensity toward observer (Correct answer)
- Color rendering index and color temperature
- Lamp lumen depreciation and dirt factor
Correct answer: Background luminance, solid angle, and luminous intensity toward observer
UGR is calculated from the background luminance, the luminous intensity of each source toward the observer, and the solid angle subtended by each source.
Question 7: In daylighting calculations using the Daylight Factor (DF) method, a DF of 5% is generally considered:
- Too dim for any occupied space
- Well-daylit, potentially requiring glare control (Correct answer)
- Equivalent to direct sunlight penetration
- Adequate only for storage areas
Correct answer: Well-daylit, potentially requiring glare control
A Daylight Factor of 5% or higher indicates a well-daylit space where glare and overheating may become concerns alongside the daylight benefit.
CLC Lighting Calculations & Software 3
When performing an average-to-minimum uniformity ratio calculation for a roadway, which IES standard provides guidance?