10 free, exam-style Certified Lighting Efficiency Professional (CLEP) (CLEP) practice questions with answers and explanations. No signup required. Work through them below, then take the full free CLEP practice test to study every exam domain.
The CLEP exam has 120 questions and runs 4 hours.
These 10 free CLEP questions are organized by exam domain, so you can see how each part of the Certified Lighting Efficiency Professional (CLEP) blueprint is tested. Reveal the answer and explanation under each question.
A lighting retrofit has an equipment cost of $21,000 and installation labor of $3,000, and it qualifies for a utility rebate of $4,000. The retrofit is projected to save $8,000 per year in energy and maintenance. What is the simple payback period?
Correct answer: A - 2.5 years
When evaluating a lighting capital project, an energy manager wants the single discount rate that makes the project's net present value equal to zero so it can be compared against the company's hurdle rate. This metric is the:
Correct answer: D - Internal rate of return
Two lighting systems have the same first cost, but System X uses far less energy than System Y. When a life-cycle cost comparison incorporates an annual fuel (energy) escalation rate, the effect on the comparison is that System X becomes:
Correct answer: C - More attractive, because rising energy prices raise the future value of the energy that System X saves each year
A facility engineer measures the brightness of a backlit sign as perceived by the eye and reports it in candela per square meter. Which photometric quantity has been measured?
Correct answer: B - Luminance, because it describes the light leaving the surface toward the observer's eye
A client complains that newly installed 5000K lamps make the office feel 'cold and bluish' and asks for a 'lower temperature' lamp that looks warmer. To satisfy the request, the replacement lamp should have a correlated color temperature that is:
Correct answer: C - Lower, such as 3000K, since a lower Kelvin value appears warmer
A 1,000-candela point source is aimed straight down at a work surface located 10 feet directly below it. Using the inverse-square law, the illuminance on the surface directly beneath the source is:
Correct answer: D - 10 footcandles
A luminaire mounted 8 feet above the work plane produces an intensity of 1,600 candela toward a point that is 6 feet horizontally away from the point directly below it. The slant distance to that point is 10 feet. What is the horizontal illuminance at that point?
Correct answer: A - 12.8 footcandles
Two rooms have identical surface reflectances and the same luminaires. Room A is a tall, narrow space and Room B is a low, wide space, so Room A has the higher room cavity ratio. Compared with Room B, the coefficient of utilization in Room A will be:
Correct answer: B - Lower, because a higher room cavity ratio means more light reaches the walls and is lost before the work plane
A lighting designer must determine the total light loss factor for a maintained-illuminance calculation. The applicable factors are lamp lumen depreciation = 0.85, luminaire dirt depreciation = 0.90, and ballast factor = 0.88. The total light loss factor is approximately:
Correct answer: C - 0.673
An office of 2,000 square feet requires 30 maintained footcandles. The design uses 2-lamp luminaires; each lamp delivers 2,900 rated lumens. The coefficient of utilization is 0.70 and the total light loss factor is 0.80. Using the lumen method, what is the MINIMUM number of luminaires required?
Correct answer: B - 19 luminaires
The CLEP exam also covers these domains. Drill them in the full free practice test:
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