The material and insulation of a door have a significant impact on its energy efficiency. The most common materials for doors are fiberglass, metal, and wood, and with the exception of wood, any of these doors can be insulated or uninsulated. Also, be sure that any door that you buy is Energy Star certified. Lets dig into this a bit:
Fiberglass Doors
Fiberglass doors protect against the transfer of heat and cold better than any other door. Because it doesn’t inherently conduct heat, Fiberglass is energy-efficient on it’s own. However, when insulated, it’s difficult to beat. They are also long-lasting, but they are costly.
Metal Doors
Metal doors are less expensive than fiberglass doors and have a higher insulating value, but they are not as durable and are prone to rust and dents. Metal can also traps heat and cold causing it to become hotter during the summer and colder in the winter.
Wood Doors
Because wood doors lack the thermal properties of metal and fiberglass doors, they are the least energy efficient of these options. However appealing a wood door may appear, it absorbs heat more readily than other materials, allowing heat and cold to enter your home more easily.