CLC Lighting Design & Application 3 — Questions and Answers
Question 1: Which IES recommended practice provides guidance for office lighting design in the United States?
- IES TM-30
- ANSI/IES RP-1 (Correct answer)
- IES LM-79
- IES TM-15
Correct answer: ANSI/IES RP-1
ANSI/IES RP-1 (Recommended Practice for Office Lighting) provides guidelines for illuminance levels, luminance ratios, and visual comfort in office environments.
Question 2: A designer is evaluating two luminaires: one with an LER of 85 lm/W and one with 60 lm/W. What does LER stand for and which is more efficient?
- Luminaire Efficacy Rating; the 85 lm/W unit is more efficient (Correct answer)
- Lumen Energy Ratio; the 60 lm/W unit is more efficient
- Light Emission Rate; both are equivalent
- Lamp Efficacy Ratio; the 85 lm/W unit is more efficient
Correct answer: Luminaire Efficacy Rating; the 85 lm/W unit is more efficient
LER (Luminaire Efficacy Rating) measures system lumens per watt for the complete luminaire; higher values indicate greater efficiency.
Question 3: In exterior lighting design, what is the main goal of 'full cutoff' classification?
- To maximize lumen output upward for pole-mounted fixtures
- To prevent any light from being emitted at or above 90° from nadir (Correct answer)
- To limit light output below 45° to reduce shadows
- To control color temperature of streetlights
Correct answer: To prevent any light from being emitted at or above 90° from nadir
Full cutoff luminaires emit zero candelas at 90° and above from nadir, minimizing light trespass, glare, and sky glow.
Question 4: A restaurant designer wants warm, intimate lighting. Which CCT range is most appropriate?
- 5000–6500K
- 3500–4100K
- 2700–3000K (Correct answer)
- 4000–4500K
Correct answer: 2700–3000K
2700–3000K produces warm white light that creates an intimate, flattering ambiance ideal for dining environments.
Question 5: What lighting design strategy uses a combination of ambient, task, and accent layers to provide flexibility and visual interest?
- Uniform lighting
- Layered lighting design (Correct answer)
- Single-source general lighting
- Task-only lighting
Correct answer: Layered lighting design
Layered lighting design uses multiple lighting types—ambient, task, accent, and decorative—to create flexible, visually rich environments.
Question 6: Which factor most directly affects the spacing-to-mounting-height (S/MH) ratio used in lighting layout calculations?
- The lamp's color rendering index
- The luminaire's beam spread and photometric distribution (Correct answer)
- The room's wall reflectance only
- The circuit voltage supplying the fixtures
Correct answer: The luminaire's beam spread and photometric distribution
The S/MH ratio is derived from the luminaire's photometric distribution; wider beam spreads allow greater spacing relative to mounting height.
Question 7: In a classroom lighting design, why is it important to minimize luminaire luminance in the 55°–85° zone from nadir?
- To reduce energy consumption at the driver level
- To prevent discomfort glare in the line of sight of seated students (Correct answer)
- To increase vertical illuminance on whiteboards
- To comply with NEC wiring requirements
Correct answer: To prevent discomfort glare in the line of sight of seated students
High luminance in the 55°–85° zone falls directly in a seated person's horizontal line of sight, causing discomfort glare that impairs reading and concentration.
CLC Lighting Design & Application 3
Which IES recommended practice provides guidance for office lighting design in the United States?