Final answer:
The space inside the fireplace is called the firebox. Conduction, convection, and radiation are the methods of heat transfer involved in a fireplace. Improving convection and external air supply can make a fireplace more energy efficient.
Step-by-step explanation:
The space inside the fireplace is indeed called the firebox.
Heat transfer occurs through all three methods: conduction, convection, and radiation. Conduction occurs when heat is transferred through direct contact, such as when the walls of the firebox become hot and transfer heat to the surrounding air. Convection occurs when the hot air inside the firebox rises and circulates, carrying heat with it. Finally, radiation occurs when heat is transferred through electromagnetic waves, such as the heat radiating from the glowing embers in the firebox.
By having an external air supply for the combustion of fuel and circulating room air around the outside of the firebox, a fireplace can become more energy efficient by enhancing convection and allowing more heat to be transferred into the room.