CLD Luminaire Selection 4 — Questions and Answers
Question 1: When specifying luminaires for a historically sensitive renovation, which consideration is typically prioritized alongside energy code compliance?
- Maximizing lumen output per fixture
- Maintaining the visual character and scale of original fixtures (Correct answer)
- Using the highest color temperature available
- Installing the fewest possible luminaires
Correct answer: Maintaining the visual character and scale of original fixtures
Historic preservation projects require balancing energy code mandates with maintaining the visual integrity and character of the original lighting fixtures and space.
Question 2: A luminaire's photometric data shows a beam spread of 15°. How would this typically be classified?
- Wide flood
- Medium flood
- Spot (Correct answer)
- Narrow spot
Correct answer: Spot
A 15° beam spread is classified as a spot beam, typically used for accent lighting or highlighting small, focused areas.
Question 3: For an outdoor parking structure, which luminaire characteristic is most critical in reducing energy consumption while maintaining safety illuminance levels?
- Precise photometric distribution minimizing wasted spill light (Correct answer)
- Highest lumen output available
- Widest beam spread for maximum coverage
- Highest correlated color temperature
Correct answer: Precise photometric distribution minimizing wasted spill light
Precise optical control directs lumens exactly where needed, allowing designers to meet illuminance targets with lower wattage and fewer fixtures.
Question 4: A luminaire spec sheet lists a Power Factor (PF) of 0.95. What does this tell the electrical designer?
- 5% of power drawn is wasted as heat in the driver
- The luminaire draws real and reactive power with only 5% reactive component (Correct answer)
- The luminaire has 95% light output efficiency
- The luminaire dims to 5% minimum without flickering
Correct answer: The luminaire draws real and reactive power with only 5% reactive component
A power factor of 0.95 means 95% of the volt-amperes drawn are converted to real working watts, with only 5% reactive power, indicating an efficient driver design.
Question 5: Which luminaire type would a CLD specify for grazing a rough stone or textured masonry wall to emphasize texture?
- Broad, diffuse wash luminaire mounted far from the wall
- Narrow-beam accent luminaire mounted very close to the wall surface (Correct answer)
- Large-aperture downlight centered above the wall
- Indirect luminaire reflecting off the ceiling toward the wall
Correct answer: Narrow-beam accent luminaire mounted very close to the wall surface
Grazing places a narrow beam very close and nearly parallel to a textured surface, casting strong shadows that emphasize the surface texture and relief.
Question 6: A sports facility requires luminaires meeting specific vertical illuminance targets for television broadcast. Which photometric parameter is most critical to evaluate?
- Mean horizontal illuminance (Eh)
- Mean vertical illuminance (Ev) in camera directions (Correct answer)
- Uniformity ratio on the horizontal plane
- Maximum luminance of luminaire surface
Correct answer: Mean vertical illuminance (Ev) in camera directions
Television broadcast requires adequate vertical illuminance (Ev) in the camera viewing directions to properly illuminate athletes' faces and capture fast action.
Question 7: When evaluating two luminaires with identical lumen outputs but different beam angles for a retail spotlight application, what is the primary effect of a narrower beam angle?
- Lower center-beam candlepower (CBCP)
- Higher center-beam candlepower (CBCP) (Correct answer)
- More uniform illuminance distribution
- Lower color temperature at center
Correct answer: Higher center-beam candlepower (CBCP)
Concentrating the same lumens into a narrower beam increases the center-beam candlepower (CBCP), creating a brighter, more intense accent effect on the target.
CLD Luminaire Selection 4
When specifying luminaires for a historically sensitive renovation, which consideration is typically prioritized alongside energy code compliance?