Explanation
Decreasing lighting power is a strategy that can be used to reduce the internal load of a building. Internal load is the amount of heat generated within a building by its occupants, equipment, and lighting1. Reducing lighting power can lower the internal heat gain and thus decrease the cooling demand and energy consumption of the building2. Other strategies to reduce internal load include using energy-efficient appliances, natural ventilation, daylighting, occupancy sensors, and shading devices3. References:
8.1: Internal Loads - Engineering LibreTexts
Chapter 3: Design Loads for Residential Buildings - HUD User
Internal Heat Gain - an overview | ScienceDirect Topics