Which combination of factors is most useful when evaluating a lighting upgrade?

When evaluating a lighting upgrade, focusing on efficacy, distribution, and illumination level provides a comprehensive understanding of how effective and efficient the lighting will be in a specific environment.

Efficacy refers to the amount of light produced per watt of energy consumed, which is critical in assessing the energy efficiency of the new lighting system. Distribution deals with how the light is spread throughout a space, which directly impacts the effectiveness of the lighting in illuminating the entire area without creating harsh shadows or overly bright spots. Illumination level is about the brightness of the space and ensuring it meets the intended use and comfort levels for occupants.

This combination of factors captures both the performance of the lighting and its practical application in real-world settings, making it essential for evaluating whether the upgrade will meet the needs of the building's occupants while also being energy-efficient.

While the other options include relevant factors (such as cost, lifespan, brightness, and maintenance), they do not encompass the critical aspects of distribution and illumination level, which are essential when assessing lighting effectiveness in relation to user experience and functionality.