CEA CEA Lighting & Environmental Factors 1 — Questions and Answers
Question 1: What is the recommended illuminance level (in foot-candles) for general office work according to IESNA guidelines?
- 10–20 fc
- 30–50 fc (Correct answer)
- 75–100 fc
- 150–200 fc
Correct answer: 30–50 fc
IESNA recommends 30–50 foot-candles for general office tasks to reduce eye strain while maintaining adequate visibility.
Question 2: Which type of lighting is MOST likely to cause veiling reflections on computer screens?
- Indirect uplighting
- Task lighting aimed from the side
- Overhead fluorescent luminaires positioned directly above the screen (Correct answer)
- Natural daylight from a side window
Correct answer: Overhead fluorescent luminaires positioned directly above the screen
Overhead luminaires positioned directly above a monitor create specular reflections on the screen surface, reducing contrast and increasing visual fatigue.
Question 3: What is the primary ergonomic concern when the luminance ratio between a task and its immediate surround exceeds 3:1?
- Increased glare disability
- Reduced color rendering index
- Visual fatigue from repeated pupil adaptation (Correct answer)
- Flicker sensitivity
Correct answer: Visual fatigue from repeated pupil adaptation
High luminance ratios force the eye to repeatedly adapt between bright and dim areas, causing visual fatigue over a workday.
Question 4: Thermal discomfort in an office is MOST directly evaluated by which combination of environmental parameters?
- Air temperature and CO₂ concentration
- Radiant temperature, air temperature, humidity, and air velocity (Correct answer)
- Lighting level and noise level
- Barometric pressure and humidity only
Correct answer: Radiant temperature, air temperature, humidity, and air velocity
ASHRAE 55 uses operative temperature (combining air and radiant temperature), humidity, and air velocity to assess thermal comfort.
Question 5: According to OSHA and NIOSH guidance, what is the action level for occupational noise exposure over an 8-hour TWA?
- 80 dBA
- 85 dBA (Correct answer)
- 90 dBA
- 95 dBA
Correct answer: 85 dBA
NIOSH sets the recommended exposure limit at 85 dBA as an 8-hour TWA, triggering hearing conservation program requirements.
Question 6: Which lighting metric BEST describes the ability of a light source to reveal colors accurately compared to a reference illuminant?
- Correlated Color Temperature (CCT)
- Color Rendering Index (CRI) (Correct answer)
- Luminous Efficacy
- Illuminance (lux)
Correct answer: Color Rendering Index (CRI)
CRI rates how accurately a light source renders surface colors relative to a reference source on a scale of 0–100.
CEA CEA Lighting & Environmental Factors 1
What is the recommended illuminance level (in foot-candles) for general office work according to IESNA guidelines?