Lighting Calculations & Software Flashcards
7 cards from real CLC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Lighting Calculations & Software flashcards as text
When using the point-by-point method to calculate illuminance from a single luminaire, which formula applies?
Answer: E = (I × cos θ) / d²
The inverse square law with cosine correction is E = (I cosθ)/d², where I is intensity in the direction of the point, θ is the angle of incidence, and d is the distance.
In photometric software, what is the function of 'luminaire rotation' settings in a horizontal plane?
Answer: Orients the luminaire's asymmetric distribution toward the target area
Rotating a luminaire in the horizontal plane (azimuth rotation) directs its asymmetric beam pattern toward the intended target surface.
A lighting simulation uses a Perez All-Weather Sky Model. This model is primarily used for:
Answer: Accurate daylighting simulation under all sky conditions including overcast and clear
The Perez All-Weather Sky Model parameterizes sky luminance distribution for any sky condition from fully overcast to clear, enabling accurate daylighting simulations.
What does the term 'efficacy' mean in the context of a luminaire system?
Answer: The ratio of lumens delivered to the work plane divided by total system watts
System efficacy (lm/W) represents how efficiently the entire luminaire system — lamp, ballast/driver, and optics — converts electrical power into useful light output.
In emergency egress lighting calculations per NFPA 101, the minimum average illuminance at floor level must be:
Answer: 1.0 footcandle
NFPA 101 requires a minimum average of 1.0 fc at floor level along the path of egress during emergency lighting operation.
When DIALux EVO imports an IES file and renders a 3D visualization, what does the 'luminous flux' value in the file represent?
Answer: The total light output of the lamp inside the fixture in lumens
The luminous flux in an IES file represents the total lumen output emitted by the lamp(s), used as a reference for the photometric data.
A retail store has a calculated LPD of 1.8 W/ft². ASHRAE 90.1-2019 allows 1.4 W/ft² for retail. Which solution reduces LPD without redesigning the layout?
Answer: Switch to lower-wattage LED drivers or reduce fixture count
Reducing driver wattage (using lower-wattage LED drivers or dimming to a set point) or removing excess fixtures directly reduces the installed wattage and thus LPD.