NCIDQ Lighting Design 2 — Questions and Answers
Question 1: A luminaire's efficacy is expressed as which unit of measurement?
- Lumens per watt (Correct answer)
- Watts per square foot
- Candela per square meter
- Footcandles per lumen
Correct answer: Lumens per watt
Luminaire efficacy is measured in lumens per watt (lm/W), representing how efficiently a fixture converts electrical energy into visible light output.
Question 2: According to IES recommendations, what is the typical illuminance range for general office tasks such as reading and computer work?
- 5–10 footcandles
- 30–50 footcandles (Correct answer)
- 150–200 footcandles
- 300–500 footcandles
Correct answer: 30–50 footcandles
IES recommends 30–50 footcandles (300–500 lux) for general office tasks, with higher levels for detailed or visually demanding work.
Question 3: In healthcare examination rooms, which lighting characteristic is most critical for accurate diagnosis and skin tone assessment?
- Warm color temperature (2700K) for patient comfort
- High CRI (90+) for accurate color rendering (Correct answer)
- Low illuminance to minimize visual fatigue
- Indirect lighting to eliminate all shadows
Correct answer: High CRI (90+) for accurate color rendering
A high CRI of 90 or above is essential in examination areas so that clinicians can accurately assess skin tone, tissue color, and other color-dependent clinical indicators.
Question 4: Which lighting technique involves aiming light parallel to a textured wall surface to emphasize its surface relief and texture?
- Wall washing
- Uplighting
- Downlighting
- Grazing (Correct answer)
Correct answer: Grazing
Grazing places fixtures very close to a textured surface and directs light at an oblique angle, casting dramatic shadows that accentuate texture and surface relief.
Question 5: ASHRAE 90.1 establishes energy efficiency requirements for commercial buildings by limiting which lighting metric?
- Minimum CRI for workplaces
- Lighting Power Density (LPD) in watts per square foot (Correct answer)
- Maximum color temperature for offices
- Emergency lighting duration requirements
Correct answer: Lighting Power Density (LPD) in watts per square foot
ASHRAE 90.1 sets Lighting Power Density (LPD) limits in watts per square foot for different building and space types to reduce overall energy consumption.
Question 6: Which publication from the Illuminating Engineering Society (IES) serves as the primary US reference for recommended illuminance levels and lighting design standards?
- IES Lighting Handbook (Correct answer)
- ASHRAE Fundamentals Handbook
- NFPA 101 Life Safety Code
- ICC International Building Code
Correct answer: IES Lighting Handbook
The IES Lighting Handbook is the authoritative reference for illuminance recommendations, design criteria, and best practices for all interior and exterior lighting applications in the US.
Question 7: What does the term 'wall washing' describe in interior lighting design?
- Cleaning luminaire lenses to maintain output
- Evenly illuminating a vertical wall surface from top to bottom (Correct answer)
- Directing light upward to reflect off the ceiling
- Using colored filters to tint wall surfaces
Correct answer: Evenly illuminating a vertical wall surface from top to bottom
Wall washing uses fixtures positioned to distribute light evenly across an entire vertical wall surface, creating a bright, uniform glow that makes the space feel larger.
NCIDQ Lighting Design 2
A luminaire's efficacy is expressed as which unit of measurement?