Which factor does not contribute to heat gain in a conditioned space?

Energy-efficient appliances are designed to minimize energy consumption and often generate less heat compared to traditional appliances. While all other factors listed—sunshine, normal body heat from occupants, and lighting—contribute to heat gain within a conditioned space, energy-efficient appliances specifically aim to reduce the amount of energy wasted as heat. Therefore, they do not contribute significantly to heat gain, making them the correct choice in this context.

Understanding the dynamics of heat gain is vital for maintaining a comfortable indoor environment and for effective climate control. This is why focusing on energy-efficient appliances can be beneficial for reducing overall heat gain and improving energy efficiency in buildings.