What is defined as external heat gain in building performance assessment?

External heat gain in building performance assessment refers to the various ways in which heat enters a building from outside sources. This includes:

1. Solar Gain: The heat gained from the sun's rays striking the building, particularly through windows and other surfaces.

2. External Conduction Gain: The heat that enters the building through conduction from the exterior walls, roof, and flooring when they come into contact with warmer outside air or surfaces.

3. Infiltration Gain: The heat added to the indoor environment due to the unintended influx of outside air through leaks, cracks, or openings in the building envelope.

This combined effect of all three factors is crucial for accurately assessing the thermal performance of the building. Understanding these elements allows for better design and implementation of energy efficiency strategies, leading to improved thermal comfort and reduced energy consumption.

In contrast, other options do not encompass the complete range of external heat sources. Focusing solely on solar gain overlooks critical contributions from conduction and infiltration, while considering only internal gains from appliances ignores important external sources that contribute to overall thermal conditions. Evaluating total energy loss from the building is more about assessing efficiency than identifying how heat is gained from external sources. Thus, the option that includes all relevant external heat gain