CLC Lighting Design & Application 2 — Questions and Answers
Question 1: Which lighting metric best describes the amount of light falling on a surface?
- Luminous flux (lumens)
- Illuminance (footcandles or lux) (Correct answer)
- Luminance (candelas per square meter)
- Luminous intensity (candelas)
Correct answer: Illuminance (footcandles or lux)
Illuminance measures the amount of luminous flux per unit area arriving at a surface, expressed in footcandles (fc) or lux.
Question 2: A retail store wants to highlight merchandise with high contrast. Which technique is most appropriate?
- Uniform ambient lighting at high levels
- Accent lighting with a 3:1 to 5:1 accent-to-ambient ratio (Correct answer)
- Wall washing with fluorescent strips
- Low-level task lighting throughout
Correct answer: Accent lighting with a 3:1 to 5:1 accent-to-ambient ratio
Accent lighting using a 3:1 to 5:1 ratio creates the focal contrast needed to draw attention to merchandise without causing glare.
Question 3: What is the primary purpose of a photometric plan in a lighting design project?
- To select fixture styles and finishes
- To document the electrical circuit layout
- To predict light levels and distribution across a space (Correct answer)
- To specify lamp replacement schedules
Correct answer: To predict light levels and distribution across a space
A photometric plan uses calculations or software to predict illuminance levels, uniformity, and distribution before installation.
Question 4: In museum lighting, which UV threshold is commonly recommended to protect artifacts from photochemical damage?
- 75 µW/lm
- 10 µW/lm (Correct answer)
- 200 µW/lm
- 50 µW/lm
Correct answer: 10 µW/lm
Museum conservation standards typically call for UV levels at or below 10 µW/lm to minimize photochemical degradation of sensitive materials.
Question 5: Which of the following best defines 'luminaire efficiency'?
- The ratio of lumens emitted by the luminaire to the power consumed by the lamp alone
- The ratio of lumens exiting the luminaire to the total lumens produced by the lamp(s) inside (Correct answer)
- The color rendering index of the installed lamp
- The ratio of footcandles at the task plane to watts consumed
Correct answer: The ratio of lumens exiting the luminaire to the total lumens produced by the lamp(s) inside
Luminaire efficiency (or light output ratio) is the fraction of lamp lumens that actually exits the fixture after losses from optics, housing, and thermal effects.
Question 6: A healthcare facility corridor requires lighting that reduces fall risk for elderly patients. Which design parameter is most critical?
- High color temperature (6500K) for alertness
- Uniform horizontal illuminance with minimal shadows and glare control (Correct answer)
- Decorative pendant fixtures at 10-foot intervals
- Strobe-free dimming at 50% of full output
Correct answer: Uniform horizontal illuminance with minimal shadows and glare control
Uniform illuminance with controlled glare minimizes visual confusion and shadow hazards that increase fall risk for elderly patients.
Question 7: When designing daylighting integration, what does the term 'daylight autonomy' measure?
- The percentage of time a space meets its target illuminance from daylight alone (Correct answer)
- The ratio of window area to floor area
- The peak lux level achieved through skylights
- The number of hours per day that electric lights can be turned off
Correct answer: The percentage of time a space meets its target illuminance from daylight alone
Daylight autonomy (DA) is the percentage of occupied hours during a year when target illuminance is met by daylight without electric lighting.
CLC Lighting Design & Application 2
Which lighting metric best describes the amount of light falling on a surface?