Certified Energy Auditor Practice Exam

What does efficacy refer to in the context of lighting?

1. Brightness of a light bulb

2. Quantity of visible light produced per quantity of power

3. Longevity of the lighting system

4. Color temperature of light

The correct answer is: Quantity of visible light produced per quantity of power

Efficacy in the context of lighting refers specifically to the quantity of visible light produced per quantity of power consumed, typically measured in lumens per watt (lm/W). This measure is crucial because it helps determine how effectively a light source converts electrical energy into visible light. When evaluating lighting systems, higher efficacy values indicate more efficient fixtures that provide more light output for less energy consumption, which is essential for energy conservation and cost savings. Understanding efficacy is key for energy auditors, as they assess lighting systems' performance and recommend improvements or upgrades that will not only reduce energy use but also enhance overall lighting quality. The other options relate to aspects of lighting but do not capture the primary meaning of efficacy. Brightness, for instance, is a subjective perception of light intensity, longevity concerns the lifespan of the light source, and color temperature describes the hue of the light produced. Efficacy encompasses the efficiency of the light output in relation to energy input, making it a critical consideration for energy auditing practices.