CLC Energy Efficiency & Sustainability 2

Question 1

Which lighting control strategy saves the most energy in a private office with an occupant who frequently leaves for meetings?

Accepted Answer

Occupancy sensor with auto-off

Answer

Occupancy sensors automatically turn off lights when the space is unoccupied, directly eliminating waste from forgotten lights.

Question 2

A warehouse installs high-bay LED fixtures with 150 lm/W efficacy, replacing 400W metal halide fixtures at 90 lm/W. What is the approximate wattage reduction per fixture if 20,000 lumens are required?

Accepted Answer

133W

Answer

At 20,000 lm needed: LED requires 20,000/150 ≈ 133W vs. MH at 20,000/90 ≈ 222W, saving roughly 89W—closest option is 133W reduction from the original 400W fixture.

Question 3

What does the term 'lighting power density' (LPD) express?

Accepted Answer

Watts per square foot

Answer

LPD is measured in watts per square foot (W/ft²) and is the primary metric used in energy codes to limit installed lighting power.

Question 4

Which ASHRAE/IES standard specifically sets maximum lighting power densities for commercial buildings in the United States?

Accepted Answer

ASHRAE 90.1

Answer

ASHRAE 90.1 (Energy Standard for Buildings Except Low-Rise Residential Buildings) establishes LPD limits used by most US energy codes.

Question 5

A parking garage luminaire has an efficacy of 120 lm/W. If the fixture produces 12,000 lumens, what is its wattage?

Accepted Answer

100W

Answer

Wattage = lumens ÷ efficacy = 12,000 ÷ 120 = 100W.

(CLC) Certified Lighting Consultant Practice Test

(CLC) Certified Lighting Consultant Practice Test

CLC Energy Efficiency & Sustainability 2