Daylighting primarily helps reduce artificial lighting needs and improve occupant comfort.

• A. Increases artificial lighting needs
• B. Has no effect on energy use
• C. Reduces artificial lighting needs
• D. Increases energy use due to heat load

Answer: (C)

Daylighting uses natural light to illuminate interior spaces, which reduces the need for electric lighting during the day and often improves occupant comfort through better, more evenly lit spaces and a connection to the outdoors. The best choice reflects this primary effect: it reduces artificial lighting needs. While adding daylight can change cooling needs due to solar heat gain, a well-designed daylighting system with appropriate glazing and shading typically lowers total energy use by cutting lighting energy, rather than increasing it. The other statements don’t fit because they either claim more artificial lighting is needed, claim no energy impact, or emphasize heat-load increases as the main outcome, which misrepresent the overall energy savings daylighting provides.