How can daylighting affect cooling loads in a building?

• A. It has no impact
• B. Eliminates need for shading
• C. It reduces artificial lighting energy but can increase solar gains
• D. It always increases energy use

Answer: (C)

The main idea is that daylighting changes energy use by cutting electric lighting needs while also affecting heat entering the building. Daylight brings in natural light, which reduces the energy used by artificial lighting. But the same daylight travels through windows and adds solar heat to the interior, potentially increasing cooling loads if that heat isn’t controlled. The overall effect depends on climate and window design: with shading devices, high-performance glazing, and daylight controls, you can keep the cooling impact small while still reaping lighting savings. So daylighting lowers lighting energy but can raise solar gains, which is why this option is the best description.