Final answer:
Higher U-values in a building's envelope increase heat flow and reduce thermal performance, while better insulation and double-paned windows improve efficiency.
Step-by-step explanation:
Those areas of the building envelope assembly with higher U-values will increase heat flow, thereby lowering the average thermal performance of the building envelope assembly. The U-value is a measure of the thermal transmittance of a building component like a wall or window. A low U-value indicates better insulation and, therefore, less heat flow, which is desirable for energy-efficient building design.
Insulation quality directly affects a building's heat loss, and adding insulation can significantly reduce heating and cooling costs. For example, by adding an extra 8.0 cm of fiberglass insulation to an attic, you can decrease the heating costs of the house, contributing to an overall improved thermal performance of the building envelope. Furthermore, incorporating features such as thick walls, double-paned windows, and strategic window placement can optimize thermal efficiency and even enable zero-energy house designs capable of comfortable living with minimal energy use for heating and cooling.